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O. Howard, Chief. October 2, 1913. THE POTATO-TUBER MOTH.’ By F. H. Cuirrenpen, Sc. D., In Charge of Truck Crop and Stored Product Insect Investigations. INTRODUCTORY. For many years the potato-tuber moth, known scientifically as Phthorimea operculella Zell., has been the worst potato pest in California. It has now reached the State of Washington and southern Texas and menaces adjacent States. This insect feeds also upon tomato, eggplant, and tobacco, which do not, however, as a rule, suffer much injury. When it occurs on tobacco it is known as the splitworm. The mature moth of this species, which is quite small ‘and grayish in color, is shown in figure 1, a; the larva is shown in 6 and c; and the pupaind. Sizes are indicated by the size lines in the figure. The eggs may be laid upon the leaves or on other parts of the plants, and the minute caterpillars or worms quickly bore between the surfaces of the leaves or into the potato skin, which they mine in every direction, finally devouring the Be ee ee ee exterior. It is believed that there are _ ;simza operculelia): a, Moth; 6, larva, Gwo.or more generations in the course of ‘tl view; ¢, larva, dors) view; : , pupa; e, f, segments of larva, en- a summer, and certainly another one can __larged. (Redrawn from Riley and be producedinstore. Itthushappensthat 4°"? this insect belongs to both truck-crop and stored-product insect pests. An example of injury by this species to potatoes is shown in figure 2. At ais a section showing the eggs; at the left is a section of a badly infested potato containing two pits, d and f, in which the larva has been at work, while at 6 and ¢ is shown the egg, highly magnified. Figure 3 gives an exterior view of a potato which has been destroyed by the tuber moth. 1 The account here given is issued with the purpose of warning potato growers and giving general infor- Mation in regard to remedies. Work was begun on this species in 1912 and will continue. This is a revised and amplified account, first published as Circular 162 of the Bureau of Entomology. 8365°—13 ‘O27 2 FARMERS’ BULLETIN 557 DISTRIBUTION. This species is widespread in its distribution, but in this country, until the year 1912, we did not know of its rapid dissemination. Abroad it is well known in Hawaii, all portions of Australia, New Zealand, Algeria, the West Indies, Peru, and many other countries, including southern Europe. As an enemy to tobacco it has been known for several years in Florida, and in North Carolina, South Carolina, and Virginia. The species occurs in southern California practically wherever potatoes are grown commercially, extending its range northward to the Sacramento Valley. As an enemy to eggplant and ground cherry it has been observed as far north as the District of Columbia. The directions for applying remedies which follow are for the benefit of per- sons inquiring in regard to means of control. Which of these should be used can be best determined by trial in the different localities under the different conditions in which the insect exists. This applies especially to the question as to the best material for fumigation. EVIDENCE OF IMPORTANCE. As evidence of the importance of the pest Mr. J. E. Graf, working under the direction of the writer, wrote: In September, 1912, an unusual outbreak of this pest occurred at El Monte, Cal., due entirely irae 2 Work of the potatetuber moth: a, to a combination of circumstances. Thousands Section of tuber, showing eye and eggs Of acres of potatoes were planted in southern deposited aboutit; beggin outline; c,egg, California—mmany more than the market would lateralview; d,/,minesoflarvain potato. stand. This meant that the market was con- a, Natural size; b, ¢, greatly enlarged; ti nwally clogged and the prices were poor, so d, somewhat reduced. (Redrawn from . 3 ts! Riley and Howard.) that the crop was worked off very slowly. The tuber moth (Phthorimxa operculella) is always found here, but the crop is generally handled so quickly and carefully that small loss results. This year, however, careless work and the leaving of potatoes in the ground too long have given the insect a tremendous start, and now its ravages are greater than ever before. A combination of the moth and low prices has so dis- couraged many of the growers that they are leaving their potatoes to rot, and as these are becoming infested there will be a great number of moths waiting for the fall motatoes:. + * e* Later, September 17, 1912, Mr. Graf wrote in regard to injury by this species that two growers near El Monte, Cal., lost $90,000 and $70,000, respectively, on potatoes that year. Items of this kind show the necessity of investigating the problem. THE POTATO-TUBER MOTH. 3 Aside from numerous similar complaints, including the usual num- ber from California for the past two years, this species has been received from Eagle Lake and Hallettsville, Tex.; San Jose, Costa Rica; Seattle, Auburn, and Yakima, Wash.; New York City, where it has not become acclimatized so far as known; Fort Collins, Colo.; and Larimore, N. Dak. These records include only occurrences on potato. In the case of the last report the tuber moth was stated to have been imported into southern California in potatoes from China. It is doubtful if the species has been established in North Dakota, but inquiries have been made in regard to the danger of its being intro- duced there as well as into Minne- sota and many other States. REMEDIES. The potato-tuber moth is a difficult insect to control by any single method. It 13 not possi- ble to reach the tuber worms in their mines in the potatoes or in the stalks or tubers while erowing in the’ field, which makes it necessary to proceed against the pest by other meth- ods. Of these, several must be employed to insure success. CLEAN METHODS OF CULTIVATION. The first measure consists in the maintenance of clean meth- ods of cultivation. This im- plies that all infested potato plants and solanaceous weeds, F'* a cs eae atonement Pe such as ground cherry, bull net- tles, horse nettles, and volunteer potato plants, growing in the same vicinity as the potatoes, must be destroyed. This can be done by prompt burning as soon as insect infestation is manifest. The burn- ing of these weeds will eliminate places for the breeding of the insect or for its successful hibernation. Domestic animals, such as sheep and hogs, are valuable for the destruction of remnants and may be utilized by merely turning them into the field. CROP ROTATION. As in most other cases of insect injury, crop rotation is desirable where possible, and the cooperation of all potato growers of the neighborhood is practically a necessity. In certain cases, as, for ex- 4 FARMERS’ BULLETIN 557. ample, in a county where many potatoes are grown, it might be possible by legislation to enforce the discontinuance of potato planting for a year, requiring at the same time the destruction of the weeds which serve as food plants. There are several alternate food crops which do not suffer materially from this insect. About the best of these are leguminous crops, like beans, peas, cowpeas, alfalfa, and clover. These possess a dual value, as they all act as soil restorers. Sugar beets, celery, and crucifers are also good as alternate food crops. Grains may serve in the same way, as they are not attacked by the tuber moth. Care in digging is advisable in order not to cut into the tuber or leave the dug potatoes in the field over night where reinfestation could occur. FUMIGATION. While all of these remedies are of value, the best remedy is the fumigation of infested tubers with bisulphid of carbon or hydrocyanic- acid gas. If bisulphid of carbon is used, it should be at the rate of 3 pounds to 1,000 cubic feet of air space, including the potatoes; 1 ounce to a barrel of 96 pounds’ capacity would not be excessive. With an exposure of not more than 24 hours no harm should be done to the potatoes for planting. The bisulphid should be evaporated in tins, like pie plates or pie pans, and a cover should be placed on the top of the fumigating barrel or box so as to make it as nearly air-tight as possible. At the end of 24 hours the potatoes should be removed, placed in a fresh barrel, and closed up. Where it can be conveniently done, hydrocyanic-acid gas should be used in a specially constructed fumigator (see fig. 4), also gas-tight. In the case of bisulphid of carbon there is great danger in bringing the chemical into proximity to fire, such as a lighted lantern or cigar, for the gas is highly inflammable and even explosive. Then, too, the bisulphid- of-carbon method costs slightly more than the hydrocyanic-acid-gas method. Fumigation with hydrocyanic-acid gas, properly performed, is not dangerous, but if improperly performed it is decidedly dangerous to human and other animal life, as the fumes are very poisonous and are deadly when inhaled in any amount. This gas is more penetrating than bisulphid of carbon and can be used by an intelligent person without trouble, if he first familiarizes himself thoroughly with the procedure by carefully studying the printed directions or assisting some one who has had experience in this work. The cubic contents of the receptacle to be fumigated, on which is based the amount of chemicals to be used, can be readily computed. The fumigating box shown in the illustration, which will pres- ently be described, may merely be taken as an example of what can THE POTATO-TUBER MOTH. 5 be easily constructed to meet the purpose. In the case of this box the potatoes are best fumigated in bags, which can be piled one on top of another. If bins or other fumigators are used, the proportions will vary. They can be constructed longer or shorter and lower, according to the individual needs and desires of the potato grower. Fic. 4.—Fumigator used for stored products infested by insects. (Author’s illustration.) THE CONSTRUCTION OF A FUMIGATOR. A building, box, or room (see fig. 4) of about 100 to 200 bushels capacity suitable for the fumigation of a quantity of potatoes would contain about 500 cubic feet. A fumigator of this cubic capacity might be built 8 feet square by 8 feet in height. A good, and perhaps 6 FARMERS’ BULLETIN 557. the best, means of preventing the escape of the gas is to line the fumi- gator with sheet tin, with soldered joints, and over sheathing. An- other method is to sheath the room inside, cover the walls, ceiling, and floor with tarred or heavy building paper, with joints well lapped, and cover the inside with matched ceiling boards. The fumigator should always be equipped with a tight door in which the joints have been broken, similar to the door of a refrigerator or safe, and should close with two refrigerator catches against a thick felt weather strip, which should render it practically gas-tight. Thus constructed it would furnish sufficient space for the fumigation of about 200 bushels of material. There would also be sufficient space for the application and diffusion of the carbon bisulphid, hydrocyanic-acid gas, or other fumigant from the top with a charge more than necessary for the quantity of potatoes treated. It sometimes happens that the price of potatoes is so low that the small grower can not well afford to expend the amount of money which would be necessary for the construction of a special fumigator. In such a case it would be advisable to use a barrel, preferably a large oil barrel, with a tight-fitting cover for fumigating. It is possible also to fumigate, but not thoroughly, piles of tubers by covering them as tightly as possible with canvas, such as 10-ounce duck or tarpaulin. PROTECTION OF THE FALL CROP AND SEED POTATOES. A special letter of warning against the ravages of the potato-tuber moth in the shape of a press notice has been sent broadcast to news- papers, as well as to others, throughout the country. The main facts in the case were founded on the.experience of Mr. Graf in his inves- tigations and in his dealings with the potato growers of southern Cali- fornia. Concisely stated, the warning is to enable potato growers to undertake special work with seed potatoes and with the fall crop. For the protection of potatoes in fall against this pest it is urged that potato growers sort the potatoes for seed two weeks after digging and again two weeks later. The uninfested tubers should then be placed in a moth-proof bin. The infested tubers may be readily picked out because of the excrement of the larvee which adheres by webbing to the outer skin of the potatoes. The tubers in the moth- proof bin, after final sorting, should be fumigated with carbon bisul- phid (bisulphid of carbon) to destroy any moths which might have bred out or have obtained entrance through other means. Growers should now keep a careful lookout both in the field and among the fumigated tubers. At first those which have been fumigated should be inspected daily. Afterwards observations may be made every other day until finally once a -week will suffice. If there should be any indication that the tuber moth is propagating, a second fumigation is in order. THE POTATO-TUBER MOTH. vi This method of saving seed potatoes appears so simple, although effective, that it is feared that many growers may disregard it. To grow all potatoes successfully the farmer should work overtime on a cleaning-up campaign which should begin at once on receipt of this bullet. Small or useless tubers and tops should be promptly cleaned up and burned, and the land should be harrowed to break up clods and leave as few hiding places as possible for the moths. All weeds and other plants of the potato kind should be destroyed over large areas surrounding the potato fields. It is particularly urged that potato growers cooperate in this work, which will lessen very materially the numbers of moths and hence reduce the chances for propagation. Could general cooperation be secured by legislation or otherwise it would be possible to restrict the distribution of this species to the area which it now occupies or to stamp it out where now established. Slipshod methods of raising potatoes at such a time as midsummer or early autumn are particularly dangerous, and in infested districts it is advisable in many cases to raise some crop other than potatoes, because unless protective and defensive measures are adopted at once there will be a serious re- duction of the potato crop and similar trouble will be experienced during seasons to come. O WASHINGTON : GOVERNMENT PRINTING OFFICE : 1913 ».DEPARTMENT OF AGRICULTURE rs WZ ‘WR : 7 Wari YE ZI 564 Contribution from the Bureau of Entomology, L. O. Howard, Chief. January 29, 1914. THE GIPSY MOTH AND THE BROWN-TAIL MOTH, WITH SUGGESTIONS FOR THEIR CONTROL. By A. F. BURGESS, In Charge of Gipsy Moth and Brown-tail Moth Investigations. INTRODUCTION. In 1869 a number of egg clusters of the gipsy moth (Porthetria dispar L.), a destructive insect pest in Europe, were brought from France to Medford, Mass., by a naturalist who was carrying on ex- perimental work with insects. Later in the season some of the cater- pillars escaped, and although none was found in the vicinity during the next few years, enough specimens survived to enable the species to establish itself. In the summer of 1889 this insect became so abundant that fruit and shade trees in the neighborhood were com- pletely defoliated, and the caterpillars swarmed over the trees and into the houses and became a serious nuisance. This resulted in the loss of valuable trees and in the depreciation of property values in that-section. For about 10 years effective work against the gipsy moth was car- ried on by the State of Massachusetts, and during this period the insect was kept under control. The work was discontinued in 1900, but the species had become so abundant and had caused such wide- spread injury by 1905 that systematic work was renewed by the State in order to protect the tree growth in the infested area. This work has been continued up to the present time, and as the insect has spread to other New England States it has become necessary to institute more extensive control measures. In 1906, after the gipsy moth had become established in New Hampshire and Rhode Island, as well as in Massachusetts, an ap- propriation*was made by Congress for suppressing it, and the Secre- tary of Agriculture was authorized to take all possible measures to prevent its spread. Since that time work has been carried on each year. The area now known to be infested is shown on the accom- panying map (fig. 1). The brown-tail moth (Zuproctis chrysorrhwa VL.) was first found in the United States in Somerville, Mass., during the summer of 1897 18474°—Bull. 564—14—_1 2 FARMERS’ BULLETIN 564. and was undoubtedly introduced some seasons previous to that time on imported nursery stock. The work of preventing damage by this insect was undertaken by the State of Massachusetts soon after the pest was discovered. This species occurs in many sections of Europe and is often seriously injurious. It spreads rapidly because the females are able to fly long distances. The accompanying map (fig. 1) shows the area in New England which is now infested by the 3 Sots ol "AREA INFESTED “°° QUARANTINED abs FOR THE iH GIrPsy MOTH 2010 THE SRO MOTH | NEW ENGLAND SH/3- pee PINS A Shaded area infested by Gipsy (ofp. put eres os: Area east of. PED! tie Wlested YS Srownteil Hobe a ps akan ie de er ee Sau ie PE oa Fic, 1.—Map showing area infested and quarantined for the gipsy moth and the brown-tail moth, 1913. (Original.) brown-tail moth. Suppressive measures by the New England States and by the Federal Government have been directed against this in- sect as well as against the gipsy moth. It is the purpose of this bulletin to give a brief statement of the life history and habits of these two species and to suggest the best methods that can be adopted for their control, GIPSY MOTH AND BROWN-TAIL MOTH AND THEIR CONTROL. 3 The methods of protecting orchards and the street, park, and orna- mental trees in cities and towns are set forth on the following pages, and these methods have been adopted as a result of many extensive experiments. A proper system of orchard management can be adopted which will enable the owner of infested trees to protect them fully without very much expense additional to that required for the control of the other injurious orchard insects. The expense of caring for infested city or park trees is somewhat greater than in the case of infested orchards, but practical methods can be adopted which will not render the cost prohibitive. The control of these insects in forests is extremely difficult, owing to the small amount of money that any owner can afford to expend in preventing injury to his woodlands. This being so it is usually more satisfactory to have the woodland examined by an expert familiar with the insects and the best measures to be used for their control in order that suggestions for treatment may be made which will be applicable to the conditions in each particular case. Such in- formation can usually be obtained from the State or local officials engaged in gipsy moth and brown-tail moth work, and so far as possible this office will cooperate with owners and give practical advice and suggestions as to the management of their infested _ premises. THE GIPSY MOTH. LIFE HISTORY. (Fig. 2.) The eggs—The female gipsy moth deposits a cluster containing 400 eggs or more, which she covers with buff-colored hair. Most of the egg clusters are laid during the month of July and hatch about the time the leaves begin to appear the following spring. They are deposited on the underside of branches of trees, on tree trunks, under loose bark, or in cavities in the trunks or branches, and are sometimes placed on stones or rubbish and in a variety of situations where they are concealed from view. As the female moth does not fly, egg clusters are seldom found far from the food plant upon which the caterpillars developed. The larve.—tThe newly-hatched larve feed on the opening leaves, making small perforations. They grow rapidly and become full fed early in July. During this period they molt five or six times, and as they increase in size a larger proportion of the foliage is eaten, so that if the infestation is severe, trees may be completely stripped of foliage before the end of June. The pupw—When full grown the caterpillars shed their skin and transform to pup, which are chestnut brown in color and _pro- vided with tufts of yellow hairs. They remain in this dormant stage for about 10 days, after which the adult insects emerge. 4 FARMERS’ BULLETIN 564. The adults ——The male moth is dark brown in color, with black wing markings, and flies well. The female is white, with black mark- Fic. 2.—Ditferent stages of the gipsy moth (Porthetria dispar) : Egg mass on center of twig; female moth ovipositing just below ; female moth below, at left, enlarged ; male moth, somewhat reduced, immediately above; female moth immediately above, somewhat reduced; male moth with wings folded in upper left; male chrysalis at right of this; female chrysalis again at right; larva at center. (Original.) ings on the wings, and does not fly on account of the weight of the abdomen. After mating the females begin depositing eggs. GIPSY MOTH AND BROWN-TAIL MOTH AND THEIR CONTROL. 5 FOOD PLANTS. The most favored food plants of the gipsy moth are the apple, the different species of oak, gray birch, alder, and willow. In cases of bad infestation nearly all of our deciduous trees are injured to a greater or less extent, with the exception of ash. Hickory is not a favored food plant, although the foliage occasionally shows severe feeding. Chestnut will not support the gipsy moth when the cater- pillars are in the first stage, and pine will not support the first two stages; but if other food plants are present severe injury may result from feeding by the larger caterpillars. Beech is sometimes fed upon freely, and occasionally the trees are defoliated; and the same is true of poplar. INJURY CAUSED BY THE GIPSY MOTH. Unless reduced in numbers by natural enemies, or by the applica- tion of control measures, the gipsy moth is capable of causing enor- mous injury to tree growth. In the area in New England which has suffered most from this insect thousands of trees are dead as a result of defoliation. (See fig. 3.) Apple and oak have been injured most, but pine and other coniferous trees mixed with deciduous growth have suffered severely. It is undoubtedly true that many oak trees which have been se- verely weakened as a result of defoliation by the gipsy moth and the brown-tail moth have failed to recover because of the attacks of cer- tain wood-boring insects. The species which has caused the most damage in this way is Agrilus bilineatus Web., a beetle the larva of which feeds beneath the bark of injured trees. NATURAL ENEMIES. There are few insect enemies of the gipsy moth native to New England that cause any noticeable benefit in reducing its numbers. This is shown by the fact that between the years 1900 and 1905, when no systematic effort was made to suppress the insect, alarming injury resulted, and native insect enemies did not increase to any marked degree. The same is true of the work of native insectivorous birds. While they undoubtedly feed to some extent on gipsy-moth cater- pillars, there is no case on record where they have been able to control the species. The wilt disease, which possibly may have occurred in this country for many years, has only recently become sufficiently abundant to be a prominent factor in natural control. INTRODUCED PARASITES AND ENEMIES. In 1905 an effort was made by the State of Massachusetts, in co- operation with the Bureau of Entomology, United States Department of Agriculture, to introduce the parasites and natural enemies of the 6 FARMERS’ BULLETIN 564. gipsy moth from its native home in Europe and Japan. Since that time a large amount of parasitized material has been received nearly every year, and as a result some promising natural enemies have become established in this country and are assisting in bringing about the control of the species. The enemies which have become estab- (Original. ) fi i >| i= & ie rs U cosh Fig. 3.—Dead and defoliated woodland resulting from gipsy moth attack. lished and are at present destroying the largest number of gipsy-moth caterpillars and pup are a Calosoma beetle (Calosoma sycophanta L.); a tachinid fly (Compsilura concinnata Meig.), which is also a parasite of the brown-tail moth; and a species of Apanteles (A pan- teles lacteicolor Vier.), which attacks small gipsy-moth and small GIPSY MOTH AND BROWN-TAIL MOTH AND THEIR CONTROL. 7 brown-tail moth caterpillars. Two species of egg parasites, namely, Schedius kuvane How., which was imported from Japan, and Anas- tatus bifasciatus Fonsc., which was secured from Europe, have also been colonized in a portion of the* infested area and are valuable additions to the natural enemies of this insect. During the past year the work of the natural enemies of the gipsy moth, including the imported parasites, the Calosoma beetle, and the wilt disease, has served greatly to reduce the numbers of the insect in many badly infested localities. This is particularly true in the region which has been infested longest, and it is hoped that when these enemies of the moth have become established in large numbers over the entire infested territory the insect will be much less a destructive factor than it is at present. Until such time as this can be brought about, however, the most effective hand or mechanical - methods of fighting this pest should be continued. THE BROWN-TAIL MOTH. LIFE HISTORY. (Fig. 4). The eggs.—The female brown-tail moth deposits a small cluster of egos on the underside of a leaf. These eggs are usually laid in July and are covered with brown hair taken from the body of the female. Hatching begins about the 15th of August. The larve.—The newly hatched larve of this insect feed on the epidermis of the leaf and after molting once or twice begin to con- struct a winter web. This is made by drawing together several termi- nal leaves and securely fastening them by silk which is secreted by the caterpillars. The larve from one or more egg clusters live and feed in common, and as cold weather approaches they retire to the web, in which they remain during the winter. In the spring these larve leave the web as soon as the buds begin to develop and feed upon the bud scales and small leaflets. They become full-grown about the middle of June. The pupew.—After the caterpillars finish feeding they spin loose silken cocoons and pupate within them. These cocoons are some- times constructed separately, but in many cases large numbers of them are spun in a single mass. About two weeks are spent in the pupal state. The adults—kKmergence of the moth usually begins the first week in July. The adult brown-tail moth is pure white in color. The abdomen of the female is much larger than that of the male, but in both sexes the tip of the-abdomen is covered with dark-brown hairs. These moths are attracted to strong light, such as electric arc lights, and as they fly at night it is often possible to secure many specimens around the are lights in cities and towns during the first half of the month of July. (oa) FARMERS’ BULLETIN 564. FOOD PLANTS. The caterpillars of the brown-tail moth commonly feed on apple, pear, plum, oak, and willow, and they are sometimes found in con- Joleners pin Wie, 4.—Different stages of the brown-tail moth (Buproctis chrysorrhea) : Winter nest at upper left; male and female adults, lower right ; cocoon in leaves, upper right ; male and female chrysalides above, male at left ; full-grown larva in center, somewhat reduced; young larve at its left; egg mass removed from leaf, showing single eggs, at lower left; female ovipositing on leaf: egg mass also on same leaf. (Original. ) : siderable numbers on elm, maple, and rose and in smaller numbers on other common deciduous trees and shrubs. They never attack conifers and are seldom found on hickory, ash, chestnut, or birch. GIPSY MOTH AND BROWN-TAIL MOTH AND THEIR CONTROL. 9g INJURY CAUSED BY THE BROWN-TAIL MOTH. The principal injury caused by the brown-tail moth is due to the feeding habits of the larve in the spring. If the infestation is bad the caterpillars are often numerous enough to devour the leaves as fast as the trees are able to develop them. As the webs are made on the terminals, the growth of the trees is often severely checked. In Note old winter webs at tops of trees. (Original, ) Wie, 5.—Apple trees stripped by brown-tail moth caterpillars. severe infestations trees may be completely stripped (figs. 5, 6), but: as the larvee become full-grown during the first part of June, there is usually an opportunity for the trees to refoliate before midsummer. The young larve that hatch in August frequently skeletonize the leaves to a considerable extent. This does not damage the trees. seriously. as the growing period for the season is nearly ‘completed. 18474°—Bull. 564—14——2 10 FARMERS’ BULLETIN 564, The bodies of the caterpillars of the brown-tail moth are provided with poisonous hairs. A microscopic examination of these hairs shows that the edges are barbed in such a way that when they come as i ‘ fan \y Fic. 6.—Red oak trees stripped by brown-tail moth caterpillers. Note old winter webs at tops of trees. (Original.) in contact with the human skin and are pressed into the flesh, intense irritation is caused. These hairs are also hollow and contain a poi- sonous substance which acts on the blood corpuscles. This causes GIPSY MOTH AND BROWN-TAIL MOTH AND THEIR CONTROL. 11 serious poisoning and severe irritation accompanied with external swelling and is known as the brown-tail rash. There is considerable difference in the susceptibility of persons to this poison, but many cases are reported each year in the infested region, most of which are more serious than those of ivy poisoning. Many camps and sum- mer cottages, particularly in wooded areas, can not be occupied with any comfort during the early summer on account of the poisoning resulting from these caterpillars. If clothing is hung on the line near badly infested trees the hairs frequently find lodgment and are brought into the houses, and later severe poisoning may result. NATURAL ENEMIES. One of the most important natural enemies of the brown-tail moth is a fungous disease, H’ntomophthora aulicw, which attacks the cater- pillars, particularly in the spring. It was first reported in this country by Dr. Roland Thaxter in 1888. Like all diseases of this nature, the benefit derived from it is regulated largely by favorable or unfavorable weather conditions. This fungus sometimes works to a slight degree on the small caterpillars in the fall, and in some instances it is found in the winter webs. As a rule, however, the greatest mortality of caterpillars takes place in the spring, when they are nearly full-grown, and the pup of the moth may, under the most favorable conditions, be almost completely exterminated. Native parasites and predaceous insects have done very little to check the increase of the brown-tail moth. INTRODUCED PARASITES AND ENEMIES. The parasites and enemies already mentioned as being particularly valuable for their work in destroying the gipsy moth also attack the brown-tail moth, with the exception of the egg parasites. The Calosoma beetle, Calosoma sycophanta, and its larve do valuable work each year in destroying brown-tail caterpillars and pupe, and the dipterous and hymenopterous parasites also attack this species in considerable numbers. Another imported parasite, namely, J/eteorus versicolor Wesm., has become established in this country and is doing good work. It attacks the brown-tail moth caterpillars, but not those of the gipsy moth. In some parts of the infested territory where some of the first parasite liberations were made a marked decrease in the number of moths has been noted during the past two years. The work of the parasites will undoubtedly be more pronounced after they have become more abundant over the entire infested territory. 72 > FARMERS’ BULLETIN 564. HAND METHODS FOR CONTROLLING THE BROWN-TAIL MOTH. The brown-tail moth can be controlled by cutting off the winter webs and burning them before the caterpillars begin to emerge in April. These webs should be destroyed by fire, for if they are simply cut from the tree and left on the ground the caterpillars will emerge and no benefit will result from the work which has been done. In orchard practice it is sometimes inadvisable to cut the winter webs, for where an infestation is bad it is likely to leave a poorly shaped tree. Spraying in the spring is not a satisfactory remedy unless the infestation is very hght, because the caterpillars, when they occur in large numbers, do not allow the tree to put out suffi- cient foliage to hold the spray material. The most effective method is to spray the trees before the middle of August, using from 6 to 10 pounds of arsenate of lead to 100 gallons of water. Before spraying operations of this sort are attempted care should be taken to deter- mine whether the trees are well infested with egg masses of the brown-tail moth, for if the infestation is very slight it will be more satisfactory to cut and destroy the webs. If the infestation war- rants, both shade, ornamental, and fruit trees may be sprayed to advantage at this time. Caution should be used, however, in spray- ing fruit trees, particularly if early fall varieties are to be treated. If this is to be done a somewhat weaker spray solution may be used, provided it is apphed as soon as the caterpillars begin to hatch. The foliage should be treated thoroughly, particularly the terminal shoots, und as much care as possible should be exercised not to cover the fruit. Late fall or winter varieties of fruit may be sprayed in August with arsenate of lead, using 6 pounds to 100 gallons of water, und although an occasional spot may be found on the fruit at the time of picking no injury will result from it. In cases where onlv a few choice fruit trees are to be sprayed it is practicable to wipe the fruit before packing for sale; but this is not necessary if care is taken to treat the terminal growth of the trees, as this is where the bulk of the egg clusters is deposited. GENERAL HAND METHODS FOR CONTROLLING THE GIPSY MOTH. Creosote—One of the best methods of controlling the gipsy moth is to treat the egg clusters of the insect between August 1 and April 1 with creosote, to which a small amount of lampblack has been added. This mixture is applied with a brush, and it leaves a black residue on the clusters treated. Creosote may be obtained in small quantities from nearly all the large hardware or seed stores in the infested dis- trict, where it usually sells for about 35 cents a gallon. If secured in larger quantities a much lower price can be obtained. GIPSY MOTH AND BROWN-TAIL MOTH AND THEIR CONTROL. 138 Burlap bands.—Gipsy moth caterpillars usually seek shelter during hot, sunny days, and if a band of burlap is attached to a tree large numbers of them will crawl beneath it, where they may be crushed each day. Ordinarily a strip of burlap about 8 inches wide is placed (Original. ) The caterpillars beneath it are nearly all those of the brown-tail moth, Hic, 7.—Burlap band on tree, loosely around a tree trunk and a piece of twine passed around the center and tied to hold it in place. After this is done the top part of the burlap is folded down so that a double shelter is made beneath it. The use of burlap bands has been discontinued to a great extent during the last few years, owing to the expense involved and because 14 FARMERS’ BULLETIN 564. of the fact that if the burlaps are applied early in the season, before the brown-tail caterpillars have pupated, an excellent place is fur- {\ a € ao +T c 0 = 1 Fie, 8.—Tanglefoot band. Note that there are enormous numbers of gipsy moth caterpillars below the band and on the ground, but none above it. (Original.) nished for these poisonous caterpillars to make their cocoons (see lard . . . fig. 7), and severe poisoning results to the workmen. If this method GIPSY MOTH AND BROWN-TAIL MOTH AND THEIR CONTROL. 15 is to be used at all the burlap should not be attached to the trees until after June 15, when most of the brown-tail caterpillars will have pupated. Tanglefoot bands.—A band of tanglefoot may be used on tree trunks after the bark has been scraped so that the sticky material can be applied evenly in a thin layer with a paddle. The purpose of this band is to prevent caterpillars from ascending the trees, and if the egg clusters have previously been treated this is a very effective measure. It is necessary every week or 10 days during the caterpillar season to run a comb or other similar implement around the band in order to prevent hardening of the surface and to bring up fresh, sticky material from the part of the band near the bark. (See fig. 8.) Plac- ing these bands on the trees prevents the caterpillars from reaching the foliage; and as the latter usually mass in large numbers beneath the bands, conditions are favorable for wilt disease to develop, and the caterpillars often die in large numbers from this cause and from starvation. Spraying.—The most effective spray for the gipsy moth is arsenate of lead paste applied to the foliage at the rate of 10 pounds to 100 gallons of water. It is necessary that the treatment be thorough and the application even, if best results are to be secured. For small operations the ordinary orchard sprayer may be used with one or more lines of hose equipped with nozzles of the Vermorel or Bordeaux type. In case large shade trees on valuable park or woodland are to be treated, however, the use of a high-power sprayer is more econom1- cal. The type that has given the most satisfactory results in the gipsy-moth work develops sufficient power to throw a solid stream of spray into the trees. The nozzle is constructed so that the stream will break into a fine mist high im the air, and this results in very satis- factory and rapid treatment. (See fig. 9.) With such a sprayer it is unnecessary to climb trees and use small lines of hose, which is a slow and expensive operation. )- - For the purpose of comparison, illustrations are given of an unin- fested young plant (fig. 9) and an infested young plant (fig. 10). An uninfested plant is of a more slender growth, the green color is lighter, with a slight tinge of yellow, the stems are more or less visible, and the central unfolding leaf is present. The whole plant is inclined to droop and the tillers spread out and cover the ground. An infested plant is without stem and the leaves are broader, usually shorter and of a deep bluish-green color, somewhat resembling those of oats. The plant stands more erect, and, in fact, is but a mass of short overgrown leaves that usually kill with the first frost. Figure 10 shows a young tiller starting out from below the part attacked by the fly. If this tiller were to be attacked after it appeared above ground, there would follow the same appearance as in case of the original plant; that is to say, the leaves would become broader and of a darker color. The foregoing statement will apply to a severe attack on fali wheat in spring and on young spring wheat. The only exception in the appear- ance of infested young plants is in the case of the hard wheats, whose foliage is broader and of a darker color, but the erect position will still enable the observer to detect the infestation. Of course later on 69743°—Bull. 640—15——2 10 FARMERS’ BULLETIN 640. the infested plants change to yellow and then brown, but the darker color and rank growth of leaf always precede this. In summer, in both spring and fall wheat, the effect of the fly is to cause the straw to break over before harvest. It is then said to be ‘straw fallen.” Fra. 10.—Young wheat plant infested by the Hessian fly. (Author’s illustration.) IMMUNE OR DISTASTEFUL VARIETIES OF WHEATS. There is no such thing as “ fly-proof wheat.”” Most wheats will suf- fer when the plants are young, regardless of variety. In experimen- tal sowings a variety that seems to escape attack one year may suffer the next; and, while the insect may prefer certain varieties over others, this all comes to naught in years of serious ravages or where the sup- THE HESSIAN FLY. 11 posed distasteful variety is in a condition more satisfactory to the insect at the time of oviposition. It is doubtful, however, if this can be said of the attack of the second brood on the more matured plants, as it is quite noticeable that the ranker-growing varieties with strong, stiff straw are the least affected. Then, too, among fall wheats in the northern part of the country it is quite essential that a wheat plant be able to send out tillers from the old roots of plants killed by the fly (fig. 10), and that these tillers prove hardy enough to withstand the winter. Therefore, in selecting varieties of wheat with a view to evad- ing Hessian-fly attack, the farmer will do well to ignore statements on this point from those who have seed to sell and select from the varie- ties known to do well in his locality such as are of strong, vigorous growth, hardy, and with a stiff straw. For some reason the durum wheats do not seem to attract the fly, at least not the second brood. In going over fields of this kind of wheat in sections where other spring wheats were suffering from attack by this pest, 1 was rarely found on a stem of durum wheat, | while any straws of other varieties growing from seed that had become intermixed were almost invariably infested. Whether this will hold good in case of the young plants it is as yet impossible to say, because of the difficulty of telling to what varieties the young plants belong. Infested plants have been found in fields of young durum wheat in some considerable numbers; but these plants may have been of other varieties, as the fields had been used for other varieties the year belore, and besides the seed itself may have been impure. METEOROLOGICAL EFFECTS. All who have carefully studied the Hessian fly under various field conditions during a series of years have noted that weather conditions have an important influence on the msect. Especially is this true in its economic relations to the grains it attacks; hence in the applica- tion of preventive measures these weather conditions become of vital importance. Many farmers place much stress on the effect of cold weather or even of frosts in terminating the flies’ work in the fall, and it is for this reason that many try to delay wheat sowing until after there has been a sharp frost. The facts are that the females will be abroad and ovipositing in freezing weather, and Mr. W. J. Phillips has found by experimentation that the eggs will remain in a temperature of 36° F. for seventy-two hours with no other effect than to delay their hatching that much longer. This is about the temperature at which frosts would occur. Indeed, the writer has observed eggs hatching during the day in the fields when there were frosts nearly every night. Whether or not the larve from these would get sufficiently advanced 12 FARMERS’ BULLETIN 640. to pass the winter would, of course, depend upon later weather condi- tions. In the North these much-belated larvee are killed off by cold weather. The immunity of the late-sown wheat from attack by the fly is not due to frost, but to the fact that by the time severe frosts usually occur most of the flies have appeared and gone. The most marked influence of climatic conditions on this insect is seen in the effect of heat and drought, and especially of the two com- bined. In the South it is the long summer that so widely separates the two generations. Drought has a similar effect on the development of the insect as it has on the germination of the seed which produces its food; thus, dry weather in the late summer and fall tends to keep the insect in the flaxseed stage—a fact of special importance in the North where it is imperative to get the wheat sown early enough to enable the plants to stand the winter. Under exceptional conditions, such as in a dry room, flaxseeds may be kept for a year, or even two, but when moistened the flies will soon emerge. So in the fields they will, during a drought, remain in the flaxseed state for a considerable time after they would appear under normal conditions, and only appear soon after rains have moistened the soil. The first publication! dealing with the generally uniform retarda- tion of development of the fall generation from the north southward was based on work done by the author in Indiana during the years 1886 to 1890, with the aid of experimental plats sown throughout the entire length of the State. Studies of the Hessian fly in Indiana, which were begun by the author in 1884, very soon indicated that information regarding the development of this insect based on information secured in the northern part of the State would not apply at all m the extreme southern section. So far as known to the writer, this publication is the first on record relating to this particular feature of the develop- ment of the pest. Later the same investigation was continued in Ohio2 The results of this work showed very clearly that the uni- formity of development of the fall generation, which is the one most to be feared by the farmer, was practically the same in Ohio as in Indiana. Even at that time there was an indication of what might be termed a variation from the normal condition in southern Michigan. Since 1904 similar wheat-sowing experiments have been conducted from northern Michigan and northern New York to central Georgia and across the State of Kansas. As a result of the sowings in Michi- gan it was found that owing to some influence, probably that of the 1 Webster, F. M. Report on Some of the Insects Affecting Cereal Crops. The Hessian Fly. In U.S. Dept. Agr., Div. Ent., Bul. 23 (old series), pp. 63-79, 1891. ; 5 2 Bulletin No. 7, Vol. 1V, af the Ohio Agricultural Experiment Station, pee in 1891; Bulletin No. 107 of the same institution, published in 1889; and Bulletin No. 119, also of the same institution, published in June, 1900. ‘THE HESSIAN FLY. ae Great Lakes, the farmers of the southern half of southern Michigan could not sow their wheat with safety earlier than the farmers of northern Ohio, say 50 miles to the southward. It is to be pointed out that while east of the Alleghenies the Hessian fly extends from Canada southward to central Georgia, west of the Mississippi River it extends from Canada southward only to northéastern Oklahoma. (See map, fig. 8.) Over the area east of the Mississippi River climatic conditions, due seemingly to latitude, have had the effect of retarding the development of the aduit flies in the wheat stubble and their consequent appearance preparatory to egg laying in the fall for a period covering considerably oyer one month as between southern Michigan and southern Georgia. As a matter of fact, humidity, or the lack of it, seems to be a vastly more important element in influ- encing the distribution and development of the Hessian fly than either altitude or latitude. In proof of this, during seasons when the wheat crop of Sumner County, southern Kansas, was in many cases totally destroyed by the Hessian fly, at Enid, Okla., approxi- mately 40 miles away to the southward, it was only by the most dili- gent search that occasional individuals could be found in the wheat fields. The country between these localities is almost exclusively devoted to wheat, so that there was no lack of food plants, and the topography of the country is very much the same, the elevation of Enid being almost exactly that of Wellington. Not only did this condition obtain in the year 1907, but 1t was practically determined three years earlier by Mr. George I. Reeves, who made a survey of the distribution of the Hessian fly in that part of the country in the fall of 1904. The conditions up to the present remain unchanged. Furthermore, as observed by Mr. HE. O. G. Kelly, with the Hessian fly common at Kinsley, Kans., altitude 2,164 feet, and located 36 miles east of Dodge City, and destructively abundant at Great Bend, eleva- tion 1,843 feet, 82 miles northeast of Dodge City, and at Larned, elevation 1,995 feet, 60 miles from Dodge City and located between Great Bend and Kinsley, careful search at various times by several assistants of the Bureau of Entomology have utterly failed to reveal a single individual Hessian fly in the wheat fields at Dodge City, eleva- tion 2,480 feet, with wheat growing continuously between this point and Great Bend, Larned, and Kinsley. In the spring of 1913 wheat plants carrying approximately 1,200 flaxseeds of the Hessian fly were transplanted by Mr. Kelly from Sedgewick, Kans., to Dodge City, placed in a rearing cage with mesh sufficiently fine to retain the adult insects, and put in the fields April 9, 1913, under as exact field conditions as it was possible to obtain. This cage was allowed to remain in place until May 22, after there had been ample time for the flies to emerge and oviposit, whereupon it 14 FARMERS’ BULLETIN 640. . was removed. As a result of this experiment, from all of the flies developing from the transplanted wheat the offspring numbered but four individuals, showing quite conclusively that the Hessian fly can not develop in destructive abundance in that locality. This insect is destructively abundant west of the Cascade Mountains in Washing- ton and Oregon, but not in the semiarid section to the eastward. The distribution of the Hessian fly seems, therefore, to be controlled to a certain extent in the United States by conditions of bumidity. Furthermore, the development of the fall generation appears to be governed to a certain extent by the same factor. NATURAL ENEMIES. There can be no doubt that parasites play a most conspicuous part in the natural control of the Hessian fly, and if we only knew the whole truth of the matter we should find that these minute friends of the Fig. 11.—Polygnotus hiemalis, a parasite of the Hessian fly. Much enlarged. (Original.) farmer are worth many times their weight in gold. Not infrequently one species of these parasites will overcome the pest in a neighbor- hood so effectively as almost to exterminate it. Several times the writer has found, in attempting to breed the Hessian fly from young wheat plants that had been killed by the larve, that hundreds of these parasites would emerge from the flaxseeds, while only an occasional fly could be obtained. Nearly all of these deposit their eggs in the bodies of the maggots, but the fully developed parasites emerge from the flaxseeds. Prof. Herbert Osborn * has enumerated six species of these para sites, not including the English species Hntedon epigonus Walker. 1 Osborn, Herbert. The Hessian Fly in the United States. U.S. Dept. Agr., Diy. Ent., Bul. 16, 58 p., 2 pl., 8 figs., 1898. See p. 28. THE HESSIAN FLY. 15 Polygnotus minutus Lindm., which occurs in Russia, France, and HWngland, is in America represented by Polygnotus hiemalis Forbes (fig. 11), perhaps the most useful of any in this country. It is very minute, and Mr. Reeves has counted over 40 of the larve within a single flaxseed. It is black, with yellow feet, and the legs are dark brown, banded with yellow. The writer has again and again reared this in great numbers from fall wheat infested by the fly and wit- nessed the sudden check sustained by the pest the following spring. It is owing to this more than to any other influence that the Hessian fly is now being held in check in the spring-wheat regions of the Northwest, and it is probably due to a lack of this useful little insect, that the serious invasion of the Hessian fly during the year 1914 was primarily due. From all the information at present available the severe winter of 1912 and 1913 so greatly reduced its numbers as to relieve the Hessian fly from the enormous restraint that it was at that time exerting upon the pest. A vast amount of material was secured during the summer and autumn of 1914 from which this parasite could have been reared had it been present. From nowhere over the entire section of the country infested by the Hessian fly, excepting in the State of Pennsylvania, have we been able to rear the parasite, and it seems almost beyond doubt that the losses from attacks of the Hessian fly during 1914, and such as may occur during the year 1915, will be due to the absence of this parasite in the wheat fields. The occurrence of the adult within the flaxseed of the Hessian fly is illustrated in figure 12. What appears to have been a most successful intro- Fia@, 12.— Adults duction of this beneficial insect was brought about some years ago in a shipment by Mr. EH. O. G. Kelly from the Wellington, Kans., laboratory, to Mr. George I, of Polygnotus which have de- veloped within the ‘‘ flaxseed’’ of the Hessian fly andareready to emerge. Greatly en- larged. (Auth- or’s illustra- tion.) Reeves in the State of Washington. Mr. Reeves liberated these parasites in fields badly affected by the Hessian fly. Up to that time he had not been able to secure this parasite in the State of Washington, whereas since the introduction of this insect from Kansas it has become not only very common, but in some cases abundant. Another parasite reared almost invariably in connection with the Hessian fly is Hupelmus allynii French. (Fig. 13, male; fig. 14, female.) While this is generally distributed over the country and seems to be associated with the Hessian fly, and was for a long time supposed to be parasitic thereon, it now seems possible that it may be a secondary parasite and therefore the reverse of beneficial. It may be said, however, in its defense that it is most certainly a very important parasite of some other grain insects, notably the jointworms 16 FARMERS’ BULLETIN 640. and wheat straw-worms. The body is black with a greenish luster, and the legs are more or less yellow. Merisus dietasae ss ay (fig. 15) occurs in Europe, England, and America, but not in such profusion with us as to afford the same relief to the farmer as in the case of the preceding two. It also is black, but with a bluish-green metallic reflection, and the legs are black, banded with yellow. Platygaster herrickii Pack. (fig. 16) is very minute, shining black in color, and is supposed by many to attack the egg of the fly, but there is still some doubt regarding this. Beotomus subapterus Riley (fig. 17), as the name implies, has aborted wings in some individuals, while others are fully winged. The head Agios : Aig Re mm ee pee ne IK La ~ os eee. Fic. 13,—Eupelmus allynii, a parasite of the Hessian fly: Male. Much enlarged. (Original.) and thorax are of a dark greenish metallic luster, and the legs honey- yellow. Itis generally less abundant than some of the others, but sometimes individuals are quite numerous. Besides these, several undescribed species have been recorded from the northwestern part of the country. The influence of these minute parasites in regulating the world’s wheat supply is not at all under- stood, and it is doubtful if wheat could be successfully raised were they all to be suddenly swept out of existence. REMEDIAL AND PREVENTIVE MEASURES. Of remedies there is little to be said, since after the pest becomes established in a field it can not be reached by any measure likely to destroy it. The application broadeast of some quick-acting fertilizer containing a large percentage of phosphate, made as soon as general THE HESSIAN FLY. 17 infestation is apparent (see fig. 10), will cause the plants to tiller more freely and give them sufficient vigor to withstand the winter, and thus increase the number of healthy stems the following spring. Any other means that could be employed having a similar effect would be a remedial measure. All practical measures must necessarily be in the nature of pre- ventives, looking (1) to the elimination of the pest in the young wheat in the fall, and (2) to the increasing of the vigor of the young plants in order to enable them to counteract the insect’s effect, when present. Under the first come late sowing, rotation of crops, burn- ing of the old stubble, and the destruction of volunteer wheat. Under the second should be classed the enrichment of the soil, its thorough preparation, and selecting and properly sowing the best seed. By late sowing as here recommended is meant moderately late sowing of fall wheat in any locality, for extremely late sowing, which has sometimes been advised, would be even worse than early sowing. The later appearance of the fly in the fall, as we pass from the north Fia. 14.—Hupelmus ailynii, a parasite of the Hessian fiy: Female. Much enlarged. (Original.) LATE SOWING. southward, has already been explained. At present the Bureau of Entomology is conducting experiments in fall wheat sowing in nine States, covering approximately the country between latitude 33° and 46°. Here wheat is being sown every ten days during Septem- ber, October, and November, year after year, with the expectation of determining the approximate date of safety for seeding in the fall to evade attack of the fly. While these experiments have not been going on for a long enough time to give results sufficiently definite, covering all variations in the weather during these months, it is safe to say that wheat may probably be sown, without danger from Hessian fly attack, in northern Michigan soon after the first of September; in southern Michigan and northern Ohio, about Sep- tember 20; in southern Ohio, after the first week in October; in Kentucky and Tennessee, October 10 to 20; in Georgia and South Carolina, October 25 to November 15. In extreme southern Kansas and northern Oklahoma wheat should not be sown until after the first week in October; and this is true of Virginia. October-sown 18 FARMERS’ BULLETIN 640. wheat always enjoys the greatest freedom from the fly in Maryland. Practically the same corresponding delay in wheat sowing in the fall should be followed to the southward. So far these dates are only approximate, and serve to show in a general way about the time when the fall brood of the fly will have largely disappeared over the wheat belt east of the Mississippi River. As the larger part of the fall brood appears and is gone within a week, it is possible for a farmer so to time his seeding as to avoid it, and this is by far the most practical and effective preventive measure that can be applied. CROP ROTATION. Aside from the general benefits to be derived from crop rotation, this practice compels the Hessian fly, when it emerges from the Fic. 15.— Merisus destructor, a parasite of the Hessian fly. Much enlarged. (Original.) _ stubble in the fall (or spring in the Northwest), to travel a greater or less distance to reach young wheat plants. If, during this season of migration, storms or heavy winds occur, these frail creatures will be driven about or beaten down until a com- paratively small number survive to reach their destination. On the other hand, if they are not obliged to leave the field where they emerge, this mortality will be vastly lessened. BURNING STUBBLE. Burning the stubble is the most efficient measure of all, as fire will reach and destroy not only the Hessian fly but all other insects in- festing the stubble, including the joint-worm. Unfortunately it can not be generally carried out. Over a large portion of the Middle West timothy and clover are sown, either with the wheat or during late winter or early spring, and therefore stubble-ground can not be burned over. Fields not followed by grass or clover can usually be burned over if the grain is cut rather high at harvest and a mower is THE HESSIAN FLY, 19 run over the field and the mown grass, weeds, and stubble allowed to dry for a few days just before the burning. This is much the more feasible measure in the Northwest, and ought to be more generally followed. DESTRUCTION OF VOLUNTEER WHEAT. Perhaps the importance of the destruction of volunteer wheat is best illustrated by the condition frequently observed in fields of young wheat in the fall, where every volunteer plant is infested and the sown grain is entirely free from attack. The volunteer plants were above ground in time to enable the fly to deposit her eggs on them, with the result that large numbers of flaxseeds will go through the winter and the flies therefrom will deposit their eggs on the plants which constitute the crop itself. Mr.C. N. Ainslie found 157 ‘“flaxseeds’’ on a single volunteer wheat plant taken from a field in \ ae ai H iN ; \ \ Fig. 16.—Platygaster herrickii, a parasite of the Hessian fly. Much enlarged. (Original.) southwestern Iowa in October, 1914. Thus the growth of volun- teer plants menaces, to a certain degree, the crop of the following year, precisely as does a field sown too early more seriously menace adjoining fields that are uninfested in the fall. This destruction of volunteer plants by plowing, disking, or otherwise must take place before the larve have matured in order to be effective. ENRICHING THE SOIL. While it may seem “far fetched”’ to bring forward as a preventive measure the enrichment of the soil, a fertile soil will produce plants that will withstand with little injury attacks that will prove disastrous to plants growing on an impoverished or thin soil. This is because a fertile soil will enable an infested plant to tiller freely, and these tillers will have sufficient vitality to withstand the winter and send up head- producing stems in the spring. It is also chiefly on the thin or impov- 20 FARMERS’ BULLETIN 640. erished soils that the difficulty of sowing late enough to evade the fall attack and at the same time secure a growth sufficient to withstand the winter is encountered, and whatever can be done to obviate this difficulty will constitute a preventive measure. ; PROPER PREPARATION OF THE SOIL. It matters little whether a soil has much or little fertility if that fertility is bound up in clods or hard lumps out of reach of the root- lets of the young plants. Early plowing and thorough working and compacting of the soil will eliminate the lumps and clods and produce a finely pulverized, compact, moisture-conserving seed bed, from which, as soon as rootlets are sent out from the seed kernel, the shoot will begin to draw nourishment. This will give vigor to the plants and thus enable them, by freely tillering, to outgrow a light attack of the fly that _ otherwise might prove serious. THE USE OCF GOOD SEED. When we come to consider the fact that the seed kernel contains, or should contain, sufficient nutriment to put out and sustain rootlets until these can begin to draw from the soil and thus support the stem, it will be seen at once that any deficiency in the seed will necessarily tend to weaken the plant at the very beginning of its existence. Thus good seed becomes the first requisite in se- ee ere curing the healthy, vigorous plant that is to site of the Hessian fly. Much en- be further strengthened and sustained by a ee ee well-prepared, fertile soil. It is very cleart then, that all shrunken, dwarfed, or otherwise imperfect kernels should * be cleaned out of the seed before it is sown and only the largest and most perfect retained. CONCLUSION. Methods for controlling the Hessian fly, the worst pest of the wheat field, in the fall-wheat-growing sections may be summarized as fol- lows: Sow the best of seed in thoroughly prepared, fertile soil after the major portion of the fall brood has made its appearance and passed out of existence, and, if possible, sow on ground not devoted to wheat the preceding year. In the spring-wheat section late seeding will not apply. It seems likely, on the contrary, that the earlier it is sown in spring the less it will suffer from the Hessian fly. But good seed and a well-prepared, fertile soil are as essential there as elsewhere. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1915 FARMERS’ BULLETIN * me WasuinteTon, D. C. 649 Contribution from the Bureau of Entomology, L. O. Howard, Chief. ALFALFA ATTACKED BY THE CLOVER-ROOT _CURCULIO. By F. M. WEBSTER, In Charge of Cereal and Forage Insect Investigations. FEBRUARY 27, 1915. INTRODUCTION. The clover-root curculio! is of foreign origin and was not known to occur in America prior to 1876, when the late Dr. John LeConte found the beetles about the roots of grass growing on sand dunes at —_ he : s. Jere -- a reat Oe | baa of Sanaa Sa rg Fic. 1.—Present known distribution in the United States of the clover-root curculio. Long Branch, N. J. ( Original.) Just when and by what means it was first ‘brought into this country will of course never be known. It has, however, become widely diffused over the United States, as indicated 1 Sitones hispidulus Fab. Notr.—In this bulletin attention is directed to the serious injury to clover and alfalfa caused by the clover-root curculio, and a description of the insect, its feeding habits, and remedial and preventive measures are given. 73396°—Bull. 649—15 . es 2 FARMERS’ BULLETIN 649, on the accompanying map (fig. 1), showing its known distribution up to the present time. Several years ago studies were made of the insect and its attacks upon clover, although up to that time it had not been known to destroy this crop, or even to affect it seriously. Ap- parently, however, it was likely to become suffi-. ciently abundant at any time to work serious in- jury, and for this reason Mr. V. L. Wildermuth, an assistant in cereal and forage insect investiga- tions, prepared a paper which was published on March 7, 1910, as a bulletin of the Bureau of Entomology.t At that time there had hardly sufficient evidence accumulated to give this paper , any considerable economic importance. It seems, Big. 2. The clover-root however, that injuries that had either remained Greatly enlarged. unnoticed or else had been placed to the credit of (From Wildermuth.) some other pests were partly or wholly due to the work of the larva or grub of this beetle. As this insect shows a dispo- sition to occur in continu- ally increasing abundance along roadsides and im clover fields, and as it has, during the last year, been found to commit serious depredations in fields of alfalfa, it seems desirable that printed information be made available for dis- tribution among farmers, who are likely to suffer more or less from ravages of the pest. WHAT THE INSECT IS LIKE. The fully developed in- sect is a beetle (fig. 2) which attacks the leaves of clover (fig. 3, b) and alfalfa. The line at the right of figure 2 ‘ Fie, 3.—The clover-root curculio: a, Red clover root showing shows the natural length Of effects of attack by larvie; b, red clover leaf showing work of the beetle, and the eaten adults. About naturalsize. (From Wildermuth.) leaves (fig. 3, b) are plainly to be seen, especially durmg September 1 Wildermuth, V.L. The clover-root curculio (Sitones hispidulus Fab.). U.S. Dept. Agr., Bur. Ent., Bul. 85, Pt. ITI, p. 29-38, fig. 15-19, March 7, 1910. ALFALFA ATTACKED BY THE CLOVER-ROOT CURCULIO. 3 and October. They are particularly noticeable along roadsides, and ’ the writer recently observed that in many cases the majority of the clover leaves m Middletown Valley between Mount Catoctin and South Mountain, Md., were eaten in this way, although the injury was not so noticeable in the clover fields adja- cent. The most serious injury, how- ever, is not to be charged to the beetle itself, but to the larva or grub. The eggs (fig. 4) are almost spher- ical, minute, and when first depos- ited are white, but after 24 hours change to a jet black. These eggs hatch to an almost equally minute white larva (fig. 5), the head of which is of a light chocolate brown. These b j grubs are without feet and therefore "sta, Tmedherremsulby: «imme ean not travel about readily. It is deposition. Greatly enlarged. (From Wil- in this stage that the insect attacks 9°?” the roots of clover and alfalfa and is particularly injurious. When this erub becomes full grown it passes from the grub stage into what is known as the pupal stage (fig. 6) during which it requires no food and consequently is not then injurious. Fic. 5.—The clover-root curculio: Larva. SEASONAL HISTORY. areatly enlarged. (From Wildermuth.) The clover-root curculio, as stated by Mr. Wildermuth, hibernates in the beetle form; hiding itself under rubbish and leaves on the surface of the ground, probably going into hibernation, in the latitude of Washington, some time in November. These beetles remain in their winter quarters until the first warm days of spring, when the females begin to lay their eggs upon the plants on the roots of which the young grubs are to feed. That these oper- ations begin at the earliest possible date is shown by the fact that beetles were observed pairing near Hagerstown, Md., by Mr. H. L. Parker, on Septem- 16. 6.—The clover- ber 12, 1914, while Mr. Wildermuth found that bee- Geodtis 1 Mies tles taken from the fields in October or November (From Wilder- and kept in a warm room would produce eggs almost ae immediately; or if they are brought in during the winter, the same thing is observed to take place. No eggs or oviposition have been observed in the fields in the fall. 4 FARMERS’ BULLETIN 649, % According to Wildermuth: * * * the female deposits a large number of whitish eggs promiscuously on the leaves and ground or even on the side ofthe cage when confined. In the field eggs were found adhering to the lower leaves of both red clover and alfalfa. Within less than a day these eggs change in color to a shining black. It is very probable, however, that in the natural state the eggs are usually deposited at or near the surface of the eround, The egg period is 13 days in duration. The larvee immediately after hatch- ing go down into the ground. Great trouble was experienced in getting eggs to hatch in rearing cages, and it seems from this that there may possibly be some other as yet unknown condition entering into egg deposition in the field. The adult beetle endeavors to escape injury or capture by feigning death. Ifa clover plant upon which this beetle is resting be touched the beetle drops to the eround and lies there an inactive and almost invisible object. It is only when in motion that one is able to see it readily, since its color harmonizes so well with its surroundings. The larval period varies from 17 to 21 days, the latter being apparently nearer the normal, The pupal stage is passed in an earthen cell, which is oval in outline, about three- sixteenths of an inch (5 mm.) long, and half as large in diameter. The time required for the pupal stage is from 8 to 10 day s, easily determined independently of the other two stages by collecting mature larvee in the field and rearing them to adults. The larval period was determined by getting the combined length of the egg, larval, and pupal periods and subtracting from these the number of days required for the egg and pupal stages. This method was followed because of the difficulty experienced in getting the newly hatched larve to live after being transferred from the vial in which the eggs were hatched to a clover plant on which they could feed, and also because of the fact that the more fully developed larve, when disturbed to any extent, nearly always died. Thus, to avoid this, a record was kept of the day of the egg deposition in a certain cage, and then the beetles were removed and the cage leit undisturbed but watched carefully until adults appeared. The time required for this was from 38 to 43 days, thus making from 17 to 21 days for the larval stage. Tt will therefore be seen that there is but one generation of this beetle annually in the North, but the fact that adults readily deposit eggs at any time after October or early November if placed in a warm room would indicate that there might be more than one gen- eration in the warmer portions of the country, although of course this does not necessarily follow. FEEDING HABITS. The feeding habits are, so far as can be determined, almost exactly the same on alfalfa as upon clover. So far as the beetles are concerned the amount of food consumed is almost a negligible quantity, and itis, only where they gather upon clover plants along roadsides that this. sort of injury’ Neecke conspicuous. In confinement Mr. Parker found that the beetles preferred alfalfa leaves to those of red clover, eating them more readily. So far as it has been possible to deter- mine, the larve have precisely the same feeding habits on alfalfa that they have upon clover. Therefore the statements of Mr. Wilder- muth which follow are as applicable to the one plant as to the other, and they are quoted herein in full. - ALFALFA ATTACKED BY THE CLOVER-ROOT CURCULIO. 5 _- The larve of this beetle feed on the roots of all the plants mentioned as food plants. The smaller, more tender, or fibrous roots are eaten by the younger larvee which, as they become more mature, attack the larger roots. Large cavities are eaten along the main roots, and often these are in the form of a groove containing the feeding larva [fig. 3, a]. An examination of clover roots, made on September 23, showed clearly the after effects of the work of the larve. The roots were eaten at various places, some of them appearing as though the whole surface had been eaten off, the roots being scabby and brown, the damage having evidently been done during late spring or early in the summer. The adults feed on the leaves, eating out irregular patches from the margin of the leaf [fig. 3, b]. They are not as hearty eaters as some of the allied species of beetles that live on clover, and hence their work is not so noticeable, except when the beetles have developed in excessively large numbers, as was the case at Corning, N. Y: FOOD PLANTS. The following paragraphs relating to the food plants of the clover- root curculio are quoted, in substance, from Mr. Wildermuth: While the clovers seem to provide the natural food plants of this insect, there are reasons for believing that others may in future be added. This insect, when first observed in this country by Dr. LeConte, was reported by him as present around the roots of grasses growing on sand dunes. Stephens, in 1831, reported itin England as being abundant on sandy heaths, which were no doubt grown up with grass. The writer, in the spring of 1908, found the larve in large numbers in a blue-grass pasture. These were, to all appearances, feeding partly on blue-grass roots, as the only clover present was the white, and this was rather scattering in the field. From this it would seem that some of the grasses may be host plants. Of the clovers, red clover appears to be the most common choice as a food, while white clover, crimson clover, and alsike clover are all fed upon to a greater or less extent by both the adults and larve. Alfalfa seems to be a common food plant for both larvee and adults. On June 17 the writer collected numerous larve from among alfalfa roots in a field at Somerset Heights, Md., and while sweeping over a field of alfalfa with an insect net at Muirkirk, Md., on April 28, experienced no difficulty whatever in securing from six to eight adults with each sweep of the net. It seems likely that, with the increasing acreage of alfalfa, this insect may become a destruc- tive pest and also menace thiscrop. The fact that alfalfa isalways grown continuously on the same land for a fairly long period, from three to six years, or even longer, may greatly accelerate the rapidity with which the insect will be able to increase in numbers. RECENT DEPREDATIONS IN ALFALFA FIELDS. Now it will be noted that at the time Mr. Wildermuth’s paper was prepared the insect had not been observed as seriously affecting alfalfa. The first absolute proof that we were able to secure in this direction was on May 29, 1914, when Mr. J. L. Graybill, county demon- strator, of Phoenix, Md., brought to the bureau office specimens of the beetle, and also alfalfa plants that had been irretrievably dam- aged by some insect, either identical with the larvee of this species or some other one working precisely like them. Mr. A. B. Gahan was at once dispatched to the infested fields and took up the investiga- tion of the difficulty on June 4. On visiting an infested field it was 6 FARMERS’ BULLETIN 649, found that the hay crop had been cut the previous day and was lying on the ground. There appeared to be a good yield on some parts of the field, but there were many places where the alfalfa plants were very thin and evidently decidedly unhealthy. Upon examining the roots of the alfalfa on these injured areas the main taproots, and often the larger lateral roots, were badly injured. In some cases the injury consisted of a groove, generally of considerable length, up and down the root, but often of a round or oval patch. The injuries appeared to extend to a depth of 4 or 5 inches below the surface of the ground. In one case the taproot of the plant appeared to have been eaten entirely off several inches below the surface of the ground. On digging into the soil, the first shovelful of earth turned up revealed between 12 and 20 larve of this insect about the injured roots, and further investigation revealed their presence even more plentifully in other areas of the field. This condition was reported by Mr. Graybill as occurring throughout all parts of Baltimore County, Md. At the time of this investigation the larve (fig. 5) and the pups (fig. 6) were present in about equal numbers. That is, the ravages of the pest were subsiding. In all cases both of these stages were within an inch, or at the most an inch and a half, of the surface of the ground. Later on—on July 6—complaints were received, with speci- mens, from Mr. George A. Billings, of West Chester, Pa. Here again considerable damage had been inflicted upon alfalfa. On consulting with agronomists we have found that either this or a very similar injury to alfalfa has been observed for several years, but no one heretofore appears to have traced this injury to its source. Mr. C. N. Ainslie found the beetles excessively abundant in alfalfa fields in April, 1910, about Salt Lake City, Utah, but of course at that time the larvee were not at work upon the roots of the plants, and while during later years other assistants in cereal and forage insect investigations found the adults abundantly in alfalfa fields at various points in Utah, none of them succeeded in securing the larvee or observing their ravages on the roots. The work of the insect is so obscure that itis likely to escape completely the attention of alfalfa growers. NATURAL CHECKS. Our information relative to natural checks, as also that to bird enemies, has not changed materially since the publication of Mr. Wildermuth’s paper, and therefore the statements made by him are quoted. The larva was found to be attacked by a fungus, one of the Entomophthore, which no doubt assists in keeping the insects in check. The larve, because of their slug- gish movements, might be easily captured and fed upon by predaceous beetles, but the fact that the larve and pup are subterranean in their habits is a semiprotection from parasitic insects as well as from many predaceous enemies. No Hymenopterous_ or Dipterous parasites were observed. a ALFALFA ATTACKED BY THE CLOVER-ROOT CURCULIO. 7 BIRD ENEMIES. The Biological Survey, in its work on the food habits of birds, has found that the following birds feed upon the adults of this beetle: Upland plover, killdeer or kill- dee, ruffed. grouse, broad-winged hawk, flicker, nighthawk, chimney swiit, wood pewee, crow blackbird, meadowlark, Lincoln finch, song sparrow, chipping sparrow, and the white-throated sparrow. Of these birds the chimney swift and song sparrow were found to be the greatest feeders on the insect, as many as 15 adult beetles being found in the stomach of one chimney swift, while but few less were found in stomachs of song sparrows, REMEDIAL AND PREVENTIVE MEASURES. Too short a period has elapsed since we have learned of the present and probably growing importance of this msect in the alfalfa fields to enable us to carry out extensive investigations of remedial and preventive measures. This mseet occurs generally throughout Europe and eastern Siberia as well as in England. It is known to be destructive in Europe to clover, but we have no records of serious damage to alfalfa outside of the eastern United States. Within the last year it has shown itself to be capable of working very serious damage in alfalfa fields and probably has been doing so for years, but on account of the obscure way in which the injury has been done its depredations appear to have escaped attention, although the effects upon the plants seem to have been noticed for a considerable time. If this condition ean continue unobserved here in the East, there is no reason why it should not work serious ravages in the alfalfa fields throughout the entire United States where this crop is grown, and the cause of these ravages remain unnoticed even by experts. Now that we understand the nature and cause of these damages to alfalfa, it will be far easier to detect the work of the pest than has been heretofore the ease. This bulletin is prepared for the especial purpose of ealling the attention of alfalfa growers, county demonstrators, or other agri- cultural experts to its existence in this country, with the hepe that the information will enable them to detect the pest in alfalfa fields and report its presence wherever found and in this way aid in antici- pating and preventing as far as possible, by the most practical methods applicable under existing farm conditions, losses that might otherwise occur to alfalfa growers on account of the depreda- tions of the insect in their fields. Undoubtedly a short rotation of the alfalfa crop will have a tendency to limit the abundance of the pest in the fields. Of course this will not in any way affect the continuous breeding of the insect in waste lands or where clover or alfalfa occur uninter- ruptedly. The limited amount of food consumed by the adults would of itself place the application of poisons out of practical consideration. 8 | FARMERS’ BULLETIN 649. While the burning over of fields in winter when the ground is frozen might destroy some of the hibernating adults, in many cases they, would probably be so near the soil, or so intermingled with the sur- face soul, as to escape the effects of the burning, and especially would this be true if they were further protected by a covering of matted green grass. Therefore, at the present time the only practical suggestion that can be made is the disking or harrowing of the fields as soon as the first hay crop is removed. We know that the larve as a rule do not descend much more than an inch below the surface. If, there- fore, the surface of the ground were disked and then harrowed, it would seem as though the pupal cells would be broken up, and as the pest is helpless in this stage, vast numbers would be destroyed in this way. While, as stated, there has not been sufficient time to' carry out any exact experiments in this direction, it would be well for the farmers, until some better methods have been devised, to’ take the precaution of disking and harrowing immediately after! removing the first hay crop in order to destroy as many as possible ef the insects in their development. This, of course, can not be done early enough in the season to prevent injury, but it will in all proba- bility reduce largely the abundance of the pest the following season. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1915 DTT’ Stores,” UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS BULLETIN WasHINnGtoNn, D.C. 650 Marcu 30, 1915 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE SAN JOSE SCALE AND ITS CONTROL. By A. L. QUAINTANCE, In Charge of Deciduous Fruit Insect Investigations. CHARACTER OF INJURY. The San Jose or Chinese scale! infests practically all portions of its host plants that are above ground—the trunk, limbs, and branches—and when: abundant it may occur on the leaves and fruit. Injury results from the extraction, by the scale insects, of the juices of the plant. At first this merely checks growth, but as the insects increase in number the speedy killing of the branches and twigs follows, resulting finally in the death of the plants. In addition to the extraction, by the scales, of sap as food, the puncturing of the bark by the slender sucking mouth parts results in a diseased and often pitted condition; the inner bark, or cambium, shows a reddish discoloration, as exposed in cutting with a knife, and the bark itself may crack, in stone fruits exuding drops or masses of gum. A reddening effect is also much in evidence as red rings around the scales on the bark, especially of the apple and pear, and on the fruits of these plants, though not characteristic of any one scale species. On peach the scales have a tendency to infest to a greater extent the older limbs and branches than the newer growth, such as the wood 1 year old. On apple and pear the terminal twigs are quite gen- erally infested, and many of the young may find their way to the fruit, settling principally in the calyx and stem cavities. Most varieties of fruit trees and plants infested from the nursery perhaps never reach fruiting condition unless treatment be given them. Peach trees will usually be killed in two or three seasons, while pear or apple trees will maintain a feeble existence much longer. 1 Aspidiotus perniciosus Comstock; order Hemiptera, suborder Homoptera, family Coccide. 80074°—Bull. 650—15——1 to FARMERS’ BULLETIN 650. This insect, on account of its great similarity to certain other spe- cies of scale insects, may not be positively determined except by specialists. The occurrence of diseased and dying branches showing severe scale infestation furnishes strong presumptive evidence of the presence of this pest, but specimens of infested twigs should be promptly submitted to a qualified person for examination. The appearance of a three-year-old peach tree, presumably infested from the nursery, is shown in figure 1. The principal limbs have already been killed, although new shoots have developed. A tree in this condition generally may be saved by thoroughly pruning out Fia.1.—Appearance of 3-year-old peach tree badly injured by the San Jose scale, thelarger branches having been killed. (Author’s illustration.) the dead and badly injured wood and subsequently effecting the con- trol of the scale by spraying. The condition of this tree a year later is shown in figure 2, indicating the recovery following pruning and spraying. Figure 3 illustrates a badly infested six to seven year old peach orchard, the original infestation of which came from an adjacent orchard. Even in the case of peach trees so badly infested as these it is very probable that dehorning and thorough spraying would bring the trees into condition again. It is a matter of judgment, however, whether trees so seriously injured should not be removed. The character of injury to an apple orchard, in which the trees were infested from outside sources four or five years earlier, is shown THE SAN JOSE SCALE AND ITS CONTROL. o in figure 4. Although many of the limbs and branches are injured or killed, such trees may be saved and brought into vigorous condi- tion by thorough pruning and by insuring the control of the insect in the future. THE INSECT DESCRIBED. The mature San Jose scale is small, grayish in color, circular in outline, somewhat convex, and with a nipple-like prominence in the center. The female scale is about 1 millimeter in diameter (about the Fic. 2.—Appearance of peach tree shown in figure 1, one year later. The dead and injured wood was thoroughly pruned out and the San Jose scale controlled by spraying. (Original.) size of a pinhead); the male scale is much smaller and elongate. (See figs. 5 and 6.) The insect proper is beneath the so-called scale, this being simply a waxy covering secreted by the soft, helpless, yellow “louse” for its own protection. Where trees and plants are but slightly infested its presence is not readily detected by the casual observer, but in the case of severe infestation (see fig. 6) the bark of the tree 4 FARMERS’ BULLETIN 650. and limbs will present an ash-gray appearance, and on closer exami- nation will be found thoroughly inerusted with the scales, which, when scraped with a knife, will produce a yellowish, oily fluid. Fic. 3.—Appearance during summer of peach tree 6 to 7 years old badly injured by the San Jose scale. (Original.) When the scales are abundant on the tree the foliage also will be thoroughly infested, giving it a spotted and diseased appearance readily observable some feet away. THE SAN JOSE SCALE AND ITS CONTROL. 5 NATURAL HISTORY AND HABITS. The San Jose scale passes the winter in an immature condition fixed to the bark of the host plant, the small dark-gray or blackish scales being just discernible with the unaided eye. In early spring, with the ascent of the tree’s sap, the growth of the scale begins, and early in April, in the latitude of Washington, D. C., the small, two-winged, active males issue from the male scales. After mating with the females the males die. The females continue to grow and in about a month begin the production of living young—minute, 5 kA ad ah Aer HAL 7S s Mem ~~, Sy Fic. 4.—Appearance of apple orchard badly infested by the San Jose scale; many of the limbs and branches have been killed. (Author’s illustration.) yellow, oval creatures which by very close observation may be dis- tinguished without the aid of a hand lens, crawling here and there on the infested plants in an effort to find a suitable place for settlement. The young insect is active for some hours, but soon settles, pushes its slender, threadlike beak into the plant, and begins to feed by suck- ing out the sap. After this there is no further movement from place to place, and the waxy covering, which often begins to develop before the insect has settled, soon covers it completely. In about 12 days the insects molt, and from this time on the male and female scales may be readily distinguished. From 8 to 10 days later the males change to pupx, and in from 24 to 26 days from birth FARMERS’ BULLETIN 650. UT. Uf <__ Piss ae \ We iS NW gyal y ¢€ y 5 @ ee | lent ort TNF ere \ A Zs z N shies. AY) FJEZ 277 2 1) (Cx HL * r= Zerasocdt oe NWA TH Tf) Bee arte st} eNRicog Se wr © em = wh > Fia. 5.—San Jose scale: a, Adult female scale; ), male scale; c, young scales; d, larva just hatched; d’,same, much enlarged; ¢, scale removed, showing body of female beneath; /, body of female insect, more enlarged ; g, adult male of the San Jose scale. (Original. ) THE SAN JOSE SCALE AND ITS CONTROL. ri the adult males emerge and fecundate the females, which in turn reach maturity and begin the production of young in from 33 to 40 days from birth. An individual female may give birth, on the seasonal average, to about 400 young, and as the life cycle of the fe- male covers but a few weeks there may be several generations a year, the number varying according to latitude. The progeny from one parent during the season have been estimated at 1,608,040,200 females. It is thus easy to understand how the insect can so quickly destroy the plants infested and why prompt remedial measures are sonecessary. With the approach of the cool weather of fall, breeding Fig. 6.—Enlarged view ofa group of San Jose scales. (Original.) eradually ceases and the scales in all stages enter hibernation. Most of the older and also most of the younger individuals perish during the winter, the survivors being those about one-third or one-half grown, as stated. MEANS OF DISTRIBUTION. The San Jose scale is distributed from one region to another prin- cipally on nursery stock, scions, or budding and grafting material. The danger of its dissemination in this way is fully realized, and laws are in force in the majority of States requiring the inspection of nurseries and the destruction of infested stock. Traffic in nursery produce is permissible only under the certificate of an official ento- 8 FARMERS’ BULLETIN 650. mologist or inspector that the stock is free from the seale. In addi- tion to the actual inspection of nurseries, further safeguard is fur- nished by the practice of most nurserymen (compulsory in some States) of fumigating the plants, before distribution, with hydro- cyanic-acid gas. After the insect once becomes established in a locality its spread is accomplished by various agencies. As explained under the natural history of the insect, it is capable of movement only during a short period after birth. During this crawling stage the imsects are able to pass from tree to tree where the limbs are in contact, but it is Fig. 7.—Appearance ofapples infested with the San Jose scale. ( Original.) by agencies independent of itself that it is principally distributed. Prominent among these factors are birds, which may alight upon infested trees, where the young insects may crawl upon their feet and be subsequently deposited in other trees, sometimes at distances quite remote. It is probable that the young are blown by strong winds from tree to tree; and they are carried by insects, such as grasshoppers, ladybird beetles, ants, etc. The crawling ‘“‘lice” may be transported considerable distances on the clothing of man, on vehicles, or on horses or other live stock which may be in orchards for any purpose. THE SAN JOSE SCALE AND ITS CONTROL. 9 The suggestion that the insect may be disseminated by means of scale-infested fruit (see fig. 7) has been frequently made, but it is the consensus of opinion among American entomologists that this danger is negligible. FOOD PLANTS. The San Jose scale infests practically all deciduous fruit trees, such as apple, pear, peach, plum, etc., and also many ornamental and shade trees. It is, however, seriously destructive to a much smaller number than that upon which it may actually maintain its existence. The following list of food plants, as compiled by Dr. W. E. Britton,* includes those that are commonly or badly infested: Acacia sp. Lintner, Felt, N. Y.; Alwood, Va. Akebia sp. Felt, N. Y. Akebia quinata Decaisne. Alwood, Va. Shad-bush (Amelanchier canadensis Medic.), Juneberry, and other species. Britton, Koehler, Conn.; Alwood, Va. Citrus trifoliata Linn. Scott, Ga.; Alwood, Va.; Gossard, Fla. Cornus alba Linn. var. sibirica Lodd. Britton, Conn. Cornus baileyi Coult. & Evans. Gould (in N. Y.). Cornus sanguinea Linn. Britton, Conn. Cotoneaster sp.? Britton, Conn.; Lintner, Felt, N. Y.; Card, R. I. Cotoneaster vulgaris Lindl. Alwood, Va. Hawthorn (Cratezgus sp.). Britton, Conn.; Lintner, Felt, N. Y.; Alwood, Va.; Smith, N. J. , Cratzegus cordata Soland. Koehler, Conn. English hawthorn (Crategus oxryacantha Linn.). Britton, Koehler, Conn. Crategus coccinea Linn. Koehler, Conn. Crategus crus-galli Linn. Koehler, Conn. Common quince (Cydonia vulgaris Pers.). Britton, Conn.; Lintner, N. Y.; Alwood, Va. Japanese or flowering quince (Cydonia japonica Pers.). Britton, Koehler, Conn.; Lintner, N. Y.; Alwood, Va.; Johnson, Md. European purple-leaved beech ( Fagus sylvatica Linn. var. purpurea Ait.). Smith, N. J. Japanese walnut (Juglans sieboldiana Maxim). Britton, Conn.; Alwood, Va.; Sher- man, N. C.; Smith, N. J. Common privet (Ligustrum vulgare Linn.). Alwood, Va. Poplar (Populus sp.). Britton, Conn.; Smith, N. J.; Sanderson, Del.; Felt, N. Y. Carolina poplar (Populus deltoides Marsh). Britton, Conn.; Rolis & Quaintance, Fla.; Alwood, Va. Lombardy poplar (Populus nigra Linn. var. italica Du Roi). Britton, Koehler, Conn.; Rolfs & Quaintance, Fla.; Alwood, Va. Almond (Prunus amygdalus Stokes). Lintner, N. Y.; Alwood, Va. Apricot (Prunus armeniaca Linn.). Lintner, Felt, N. Y.; Alwood, Va.; Smith, N. J. Sweet cherry (Prunus avium Linn.). Britton, Conn.; Lintner, Felt, N. Y.; Alwood, Va.; Smith, N. J.; Cockerell, N. Mex. Prunus pumila Linn. Koehler, Conn. Sand cherry (Prunus pumila var. besseyi Waugh). Alwood, Va. Purple-leaved plum (Prunus cerasifera Ehrh. var. atropurpurea Dipp. (P. pissardi). Britton, Conn.; Felt, N. Y. 1 Britton, W. E. List of hardy trees, shrubs, and vines commonly or badly infested [by the San Jose scale]. Conn. Agr. Expt. Sta., Rpt. for 1902, pt. Il., 2d Rpt. State Entomologist, p. 132-138. 1903. 80074°—Bull. 650—15——2 10 FARMERS’ BULLETIN 650. European plum (Prunus domestica Linn.). Britton, Conn.; Alwood, Va. Wild goose plum (Prunus hortulana Bailey). Alwood, Va. Flowering almond (Prunus japonica Thunb.). Britton, Conn.; Felt, N. Y. Beach plum (Prunus maritima Waugh). Koehler, Britton, Conn. Peach (Prunus persica Sieb. & Zucc.). Britton, Koehier, Conn.; Lintner, Felt, N. Y.; Alwood, Va.; Cockerell, N. Mex. Japanese plum (Prunus triflora Roxbg.). Britton, Koehler, Conn.; Alwood, Va. Prunus serotina Ehrh. Koehler, Conn. Chokecherry (Prunus virginiana Linn.). Koehler, Conn. Hop tree (Ptelea trifoliata Linn.). Fernald, Mass. Pear (Pyrus communis Linn.). Britton, Koehler, Conn.; Lintner, Felt, N. Y.; Alwood, Va.; Cockerell, N. Mex. Sand pear, including Kieffer (Pyrus sinensis Lindl.). Alwood, Va. Pyrus baccata Linn. Koehler, Conn. Apple (Pyrus malus Linn.). Britton, Koehler, Conn.; Lintner, Felt, N. Y.; Alwood, Va.; Doten, Nev.; Cockerell, N. Mex. Crab apple (Pyrus sp.). Britton, Conn. Gooseberry (Ribes oxyacanthoides Linn.). Britton, Conn.; Lintner, Felt, N. Y.; Alwood, Va.; Troop, Ind. Missouri or flowering currant (Ribes awrewm Pursh.). Lintner, N.Y. Currant (Ribes rubrum Linn.). Britton, Conn.; Lintner, Felt, N. Y. Black currant (Ribes nigrum Linn.). Alwood, Va. Rosasp. Britton, Conn.; Lintner, N. Y.; Alwood, Va-.; Cockerell, N. Mex.; Burgess, Ohio; Troop, Ind.; Gould, Md.; Scott, Ga. Rosa carolina Linn. Koehler, Conn. Rosa lucida Ehrh. Koehler, Conn. Rosa virginiana Mill. Koehler, Conn. Rosa rugosa Thunb. Britton, Koehler, Conn. Willow (Salix sp.). Britton, Conn.; Felt, N. Y.; Sanderson, Del. Salix lucida Muhl. Koehler, Conn. Laurel-leaved willow (Salix pentandra Linn.). Lintner, N. Y.; Alwood, Va. Salix vitellina Linn. Koehler, Conn. Weeping willow (Salix babylonica Linn.). Lintner, N. Y.; Alwood, Va. Salix humilis Marsh. Koehler, Conn. Salix incana Schrank. Koehler, Conn. Mountain ash (Sorbus sp.). Felt, N. Y.; Hunter, Kans. American mountain ash (Sorbus americana Marsh). Britton, Koehler, Conn.; Alwood, Va. European mountain ash (Sorbus aucuparia Linn.). Britton, Koehler, Conn. Black chokeberry (Sorbus melanocarpa ©. Koch [Aronia nigra Koehne]). Koehler, Conn. Snowberry (Symphoricarpos racemosus Michx.). Felt, N. Y.; Smith, N. J. Common lilac (Syringa vulgaris Linn.). Burgess, Ohio; commissioner of agriculture, N. Y.; Troop, Ind.; Alwood, Va. Persian lilac (Syringa persica Linn.). Britton, Conn. Basswood, linden (Tilia sp.). Britton, Conn.; Lintner, commissioner of agriculture, Ne ¥:. American linden or basswood (Tilia americana Linn.). Britton, Conn.; Alwood, Va. Osage orange (Toxrylon pomiferum Rat.). Britton, Conn.; Lintner, Felt, N. Y.; Alwood, Va. Elm (Ulmus sp.). Lintner, N. Y.; Webster, Ohio; Troop, Ind. American elm ( Ulmus americana Linn.). Britton, Koehler, Conn.; Alwood, Va. English or European elm (Ulmus campestris Smith). Britton, Conn.; Felt, N. Wee Smith, N. J. THE SAN JOSE SCALE AND ITS CONTROL. Et This list might be materially extended by recording those plants upon which the insect has at various times been taken but to which it is not especially injurious. The fears earlier expressed that the scale would eventually seriously infest our native forest growth have not been borne out, and in effect it requires treatment only on fruit trees, bush fruits, and ornamental trees and plants. NATURAL ENEMIES. The San Jose scale is subject to attack by numerous predaceous and parasitic enemies, which render important service in its control. Practically, however, the combined influence of these several agen- Fic. 8.—The pitiful ladybird: a, Beetle; 6, larva; c, pupa; d, blossom end of pear, showing scales with larvee of ladybird feeding on them, and pup of ladybird attached within the calyx. All greatly enlarged. (From Howard and Marlatt.) cies is not sufficient to make up for the enormous reproductive capacity of this insect. To preserve the plants from destruction, its control must be accomplished by artificial means, such as the use of sprays. Among the more common predaceous insects which are observed feeding on the scale is the so-called pitiful ladybird,’ illustrated in figure 8. This very small, convex, black beetle may generally be found by any observant person on scale-infested trees. Another species that feeds very commonly on this and other scale 9 insects is the twice-stabbed ladybird.2. This is a very near relative 1(Pentilia) Microweisea misella Lec, 2 Chilocorus bivulnerus Muls, 12 FARMERS’ BULLETIN 650. and almost identical in appearance with the Asiatic ladybird* (fig. 9), which was introduced into this country from China through the activities of Mr. C. L. Marlatt, of the Bureau of Entomology, in the hope that its introduction would result in the control of this insect. The Asiatic ladybird, however, unfortunately proved to be subject to certain native parasites, while the necessity of spraying for the scale destroyed its food supply to such an extent that it was unable to maintain its existence. Fic. 9.—The Asiatic ladybird, almost identical with the twice-stabbed ladybird, predatory on the San Jose scale: a, Second-stage larva; b, cast skin of same; c, full-grown larva; d, method of pupation, the pupa being retained in the split larval skin; e, newly emerged adult not yet colored; f, fully colored and perfect adult. All enlarged to the same scale. (From Marlatt.) In addition to the enemies just mentioned, there are certain very minute, four-winged flies (see fig. 10) belonging to the parasitic Hymenoptera, which are true parasites of scale insects. These place their eggs beneath the scales, some species attacking the scale insect while others attack the eggs. The resulting grubs kill the insect or devour the eggs. When the parasite has become fully developed it escapes through a small, round hole which it gnaws through the scale. Parasitism of the San Jose scale by these insects can be determined by inclosing in a glass vial a badly infested twig, for in the course of a few days the minute flies, if present, will begin to emerge. Dr. L.O. Howard and Mr. R. A. Cushman have prepared the 1Chilocorus similis Rossi, THE SAN JOSE SCALE AND ITS CONTROL. 13 following list of parasites which have been reared from the San Jose scale: Aphelinus fuscipenns How., Aphelinus mytilaspidis LeB., Aphelinus diaspidis How., Aspidiotiphagus citrinus How. (fig. 10), Anaphes gracilis How., Physcus varicornis How., Prospaltella aurantii How., Prospaltella pernciosi Tower, Prospaltella fasciativentris Gir., Ablerus clisiocampae Ashin., Rhopoideus citrinus How., Perissopterus pulchellus How., Arrhenophagus chionaspidis Auriv., Anagrus spiritus Gir., Signiphora ngrita Ashm., Coccophagus immaculatus How., Coc- cophagus lecanw Fitch, and Microterys sp. While the benefits arising from the work of these parasites are un- doubtedly great, the percentage of control of the scale thus accom- plished varies greatly with the locality and the time of year, and from season to season. The highest percentage of parasitism thus far observed, and far in excess of the average, is 90. The remaining —— Meee. Fic. 10.—Aspidiotiphagus citrinus, a hymenopterous parasite of the San Jose scale. Greatly enlarged. (From Howard.) 10 per cent of healthy scales would suffice for reproduction of the scale in injurious numbers. It is, therefore, readily seen that, even with this high percentage of parasitism, the control of the scale by these agencies can not be depended upon. Considerable attention has been given to the subject of fungous diseases of the San Jose scale, and numerous attempts conducted in a thoroughly scientific manner, notably by Prof. P. H. Rolfs, director of the Florida Agricultural Experiment Station, have been made to utilize one of these parasitic plants in the control of the insect. The fungus in question, Sphaerostilbe coccophila, is cosmopolitan in its distribution, infesting many armored scale insects,! and in Florida and the territory adjacent to the Gulf it is quite generally present on scales in orchards and on shade and forest trees. Its abundance and effectiveness, however, depend upon certain weather conditions, and therefore vary considerably. 1 Subfamily Diaspine. 14 FARMERS’ BULLETIN 650 CONTROL MEASURES. As has been already stated, the San Jose scale, in the absence of proper treatment, will quickly bring about the death of many plants of economic importance. Its discovery, therefore, whether in orchards or on prized fruit trees and other plants in the yard, should call for prompt steps toward its control. It has been amply demonstrated that the scale may be very successfully controlled, and practically its presence merely requires one thorough treatment during the dormant period each year. On account of the general distribution of the pest extermination measures are, In most cases, out of the question. Complaint sometimes comes from orchardists who have the scale to contend with that the control of the insect is neglected by their neighbors, and they believe this neglect adds materially to their own work. Undoubtedly the scale will spread from orchard to orchard, but thorough annual sprayings will prevent important injury irre- spective of neglect in adjacent orchards. Where plants are thoroughly incrusted, with consequent death of branches and stunting of growth, it will generally be advisable to dig out the trees at once and replace with new ones. Before spraying infested trees the dead and weakened wood should be pruned out, which will simplify the work of spraying and will hasten the forma- tion of new, sound wood. THE WASHES IN USE AGAINST THE SAN JOSE SCALE. There are several scale washes which may be employed in the con- trol of the insect, and the one should be selected which can be most conveniently used and which is economical under the circumstances. Thus, for spraying on a large scale, the orchardists could properly afford expenditures for the construction of cooking outfits for lime- sulphur wash which would not be justified where only a few trees were involved. For a few plants .it would be better to use some one of the prepared washes put up by manufacturers. In fact, many large orchardists prefer to use sprays of this class in preference to making the washes at home. The possibility of injury to the trees from the sprays must also be borne in mind. All treatments, if pos- sible, should be made during the dormant period (that is to say, in late fall or early spring, or even during the winter in mild climates), since at this time washes may be applied at much greater strengths than when the trees are in foliage. The aim is to use the wash about as strong as the tree will stand, thereby securing the maximum kill- ing effect upon the insects. Used in this way the washes of the petroleum or kerosene series are most likely to cause injury to the fruit buds and tender twigs, and the lime-sulphur washes least likely to do so. Fish-oil soap sprays as recommended for dormant trees are comparatively safe, though reports are at hand of injury to THE SAN JOSE SCALE AND ITS CONTROL. 15 fruit buds, especially from fall applications. Stone fruits, such as peach, plum, etc., are more susceptible to injury from sprays than apple and pear, and on the former the lime-sulphur sprays should always be used. Petroleum and miscible oils are more frequently used on apple and pear, and owing to their spreading and penetrating qualities are perhaps more effective in destroying the scales on the terminal twigs, which are infested to a greater extent in the case of these fruits. The several sprays in use may be considered under the following headings: (1) Lime-sulphur wash series; (2) petroleum-oil series (including miscible oils), and (3) soap washes. LIME-SULPHUR WASH SERIES. For several years the cooked lime-sulphur wash was the main reliance in the control of the scale. It is made according to the following formula: PROTO SUUTIIO 2 ePeSU ae ag lt fe. SE A PE Sy Ae le pounds.. 20 Sulphur (dour or flowers)=... ......'. Pees... 2.c5-00l. 2 hae dos) ak GWE ARO 10002 ae ee, |S ee er a ee gallons.. 50 Heat in a cooking barrel or vessel about one-third of the total quantity of water required. When the water is hot add all the lime and at once add all the sulphur, which previously should have been made into a thick paste with water. After the lime has slaked, about another third of the water should be added, preferably hot, and the cooking should be continued for one hour, when the final dilution may be made, using either hot or cold water, as is most convenient. The boiling due to the slaking of the lime thoroughly mixes the ingre- dients at the start, but subsequent stirring is necessary if the wash is cooked by direct heat in kettles. If cooked by steam, no stirring will be necessary. After the wash has been prepared it must be well strained as it is being run into the spray tank. It may be cooked in large kettles, or preferably by steam in barrels or tanks. This wash should be applied promptly after preparation, since, as made by this formula, there is crystallization of the sulphur and hardening of the sediment upon cooling. Probably comparatively few fruit growers at the present time prepare the wash according to this old method, but employ the commercial or homemade concentrate. CoMMERCIAL LIME-SULPHUR CONCENTRATES. The inconvenience experienced in preparing the lime-sulphur wash according to the foregoing formula by cooking with steam or in open kettles at home has been one of the principal objections to this spray. Manufacturers have, therefore, put on the market concen- trated solutions of lime-sulphur which have only to be diluted with water for use. These commercial washes, if used at proper strength, have proved to be quite as satisfactory in controlling the scale as 16 FARMERS’ BULLETIN 650. the old-formula lime-sulphur wash, and, although somewhat more expensive, have been adopted by many of the commercial orchardists in preference to the ‘‘20-15-50” formula. They are especially useful for the smaller orchardists whose interests do not warrant the con- struction of a cooking plant. HoMEMADE LIME-SULPHUR CONCENTRATES. The question of the preparation at home of concentrated lime- sulphur solutions which will not crystallize upon cooling, thus dupli- cating the commercial product, has been investigated by the Bureau of Entomology, as well as by numerous experiment station entomolo- gists, notably by Profs. Stewart, Cordley, Parrott, and others. It has been demonstrated that it is practicable for orchardists to pre- pare concentrated stock solutions of lime-sulphur wash for immediate or later use, and many orchardists employ this plan. The necessary details for the preparation at home of lime-sulphur concentrates are given below. DIRECTIONS FOR PREPARATION OF LIME-SULPHUR CONCENTRATES. The so-called 50-100—50 formula, composed of 50 pounds of lime, 100 pounds of sulphur, and water to make 50 gallons, has been generally recommended ‘for the preparation of a homemade con- centrated lime-sulphur solution. Some advise the use of five or six pounds of sulphur more than above stated in order to have a slight excess of this ingredient over the lime. The method of preparation is to boil together in the necessary water the respective ingredients for from 50 minutes to an hour. A good grade of fresh stone lime containing not less than 90 per cent of calcium oxid is necessary for the best results. Hydrated lime is sometimes used, but it is necessary to use a good grade and at least 20 per cent more of this form of lime is required, as it contains a high percentage of moisture. Place enough water in the cooking vessel to finish with 50 gallons of the solution; bring the water to the boiling point, then put in the lime and immediately add the sulphur. If the plant is equipped with an agitator, this should be started with the addition of lime and sulphur. If there is no mechanical agitator, the mixture must be stirred vigorously by hand until the lime is slaked, and necessary agitation must be given throughout the time of cooking. If the solution is to be put in barrels without filtering, it should be drawn off as soon as the period of cooking is completed, and allowed to run through a 30-mesh strainer into the barrels. The agitation should be continued while the solution is being drawn off so that there will be an equal distribution of the sludge in the different storage recep- tacles. THE SAN JOSE SCALE AND ITS CONTROL. ly The density of the concentrate, made according to the formula 50—100-—50, has varied, in the experience of the Bureau of Entomology, from 24 to 28 degrees Baumé, and theoretically should be 26° by this scale. It is quite desirable for economy in storage space to prepare as highly concentrated a solution as possible. This can be done with reduced quantity of water after the following formula, which will give a solution of a density of from 32 to 34 degrees Baumé. JD e SDS) Revie ial LU 10 cen een a , < -) ee pounds.. 80 Wommercialleround’sulphur-.2.U2).. eRe IS. 2). do 160 Water to make, of the finished product....................gallons.. 50 While this formula gives about 50 per cent in volume of sludge, after allowing the solution to settle for 24 hours, there is only about 5 to 10 per cent in volume of insoluble material, which would be removed in the straining process. This volume of sludge will not be objectionable in spraying, provided the insoluble material has been properly strained out. HANDLING AND STORAGE. It is very desirable in most cases to make up a supply of lime-sulphur solution during the winter or early spring, before spraying operations begin. It is quite feasible to do this, as the solution can be kept a year or more when properly stored. It should be placed in barrels or other tight receptacles and carefully stoppered so as to exclude the air as much as possible, as this slowly causes the wash to deteriorate. The barrels or other container should be completely filled, so that there will be little or no air space above the surface of the liquid. In the prepa- ration of the lime-sulphur concentrate at home the disposition of the sludge is a question of practical importance. Commercial manufac- turing plants are usually supplied with a filter press by means of which the wash, as it comes from the cooking tank, is filtered, freeing it from sludge and sediment. There seems, however, to be no objec- tion to storing the solution without removal of sludge, though the sediment should be strained out as already stated. Lime-sulphur solution should not be allowed to freeze, as this greatly reduces its strength. It does not freeze easily, however, and the temperature at which it freezes varies with its strength; the stronger the solution, the less easily it is frozen. It will stand a con- siderably lower temperature without freezing than will water. COOKING PLANTS. Lime-sulphur concentrate may be made by orchardists with very simple appliances, such as a large kettle suspended on a pole or raised from the ground on loose stones. One or two such kettles embedded in masonry would be more convenient, however, and would permit the 18 FARMERS’ BULLETIN 650. development of necessary facilities for water supply. (See fig. 11.) Ordinary feed cookers or jacketed kettles are also very satisfactory. Small steam boilers of a few horsepower capacity serve especially well for a medium-sized orchard. . Where the amount of concentrate to be made is considerable, as for a large orchard or for the fruit growers of a neighborhood, it will pay to construct a more elaborate cooking plant. A convenient outfit is shown in figure 12. In the construction of these plants careful atten- tion should be given to the arrangement of the cooking vessel, the water supply, and the arrangement for drawing off the cooked wash. A Oo Ne =, ON ‘OS eee = 2S. om 1 ~ -_o Bakar od Fig. 11.—Lime-sulphur cooking outfit for preparing wash for small to medium sized orchards. Prepared by E. W. Scott. (Original.) 12-horsepower boiler will furnish sufficient steam for a cooker of 300 gallons capacity. However, if a steam engine is to be used for run- ning the agitator, a somewhat larger boiler will be necessary. The cooking vessel may be either of wood or iron, though an iron vessel is usually more satisfactory owing to the difficulty in preventing leakage of wooden vessels. If the cooking vessel is not provided with a pump it should be so elevated that the cooked concentrate may be drawn off by gravity into a settling tank or storage vessels. Vinegar barrels, or barrels which have been used for acids, should not be employed in storing the solution, as the acid breaks down the concentrate. Kero- sene oil barrels and whisky barrels are used to a large extent. 19 THE SAN JOSE SCALE AND ITS CONTROL CTeUrsI19) “42009 “MA “| Aq poredorg *jorreq o8v1048 04 AT}O9ITp YA SULy00d uroIy 0ye.11UEDTIOD YO SuTMvIp Joy eATeA pue odid ‘o Syme, Surp}40s 03 VA SULYOOO WOT 01BI]UDUOD Yo SUIMBIP IOJ OATBA pue odd ‘w ‘yea SUTY009 04 Yue} ATddns 1907eM wouy odtd “w ‘yueq ATddns 102M Ur JojVM SuT}eoy soy odrd ureays ‘7 {ayeryUDU00 Inyd[ns-oury] oy} Suryooo 10y odrd wree3s “yY :OUTSUd 0} IeTIOd WoIT edid ureeys ‘f {104K 718" SUTUUNLI 10; oUTSUS UIRE}S “a -1oTTOq, WiRAYs ‘y ‘TassoA SuTy000 wody ATJOOITp WA BAP ST 0} eIYUDTIOD Woy ures ‘f 19181} W80U0N ANYdNs-ounty oy} BUTIO}S 10} Jorreg “f Syue4y BUIT}}0S ‘a Syuey ATddns z07BM ‘ P ‘Inyd[ns pure eurry yo yaoddns IOJ Woods ‘9 LOB IIHR “g ‘yURy Suryoog ‘y :yueyd suTyooo AnYd[Ns-ourry os1e] B Ur syed JO JUsMIES UBB JO WOT}e UESoIdor OFYVULUIBISeI— ZL “OT 20 FARMERS’ BULLETIN 650. DILUTION. It is very important to test with a hydrometer the strength of all lime-sulphur solutions prepared, to determine the proper amount of the concentrate that should be used for a given quantity of water. There are two kinds of these hydrometers, one with the Baumé scale and the other with the specific gravity scale, and hydrometers may be purchased which have both scales on the same instrument. The Baumé scale hydrometer is most commonly used. The clear solution at a temperature of about 60° F. should be used for the testing. _ If, however, the sludge has not been filtered out, the contents of the bar- rel or other container should be thoroughly stirred before the required amount for testing is taken out. Below is given a table (Table I) from which can be determined the amount of dilution for concentrates for each degree Baumé from 20 to 36, and the corresponding specific-gravity reading. Figure 13 illus- trates the kind of hydrometers to be used in testing lime-sulphur concentrates. TasLe I.—Dilution table for concentrated lime-sulphur solutions. Number gallons concentrated Number gallons concentrated lime-sulphur to make 50 lime-sulphur to make 50 gallons spray solution. gallons spray solution. Degrees | Specific 7 ; Degrees | Specific | seers a on Baumeé. | gravity. W ee _— Baumé. | gravity. | W ete eon aoe Summer | Summer or foliage | or foliage strength. | gan Jose| Blister strength. | san Jose | Blister seale. mite. | seale. mite. | 36 1. 330 1k 5h 43 | 27 1. 229 2 8 63 35 1. 318 L 53 5 | 26 1.218 2 83 7h 34 1. 306 13 6 5 25 1. 208 2 83 1% 33 1. 295 ie 61 5i 24 1. 198 21 gt 8 32 1. 283 14 6s 53 23 1. 188 24 93 8} 31 e272 13 63 53 22 1.179 21 104 33 30 1. 261 13 7 6 21 1. 169 23 11 9} 29 1. 250 13 74 6t 20 1. 160 21 114 93 28 1. 239 13 7 64 In spraying for the San Jose scale and the pear-leaf blister mite about 5 per cent more of the solution should be used than the table of dilutions indicates, if the sludge has not been filtered out. Imnsum- mer spraying, however, no allowance for sludge is necessary, as a large percentage of this is composed of finely divided sulphur, which is of value. Lime-SutpHuR WASHES FOR SUMMER SPRAYING OF THE SAN JOSE SCALE. The lime-sulphur washes discussed on the preceding pages are intended for use on trees in a dormant condition. It sometimes happens that owing to unfavorable weather conditions during the time of the dormant spraying, or for other reasons, the insect has not been prop- erly destroyed, and it becomes desirable to spray the trees during the THE SAN JOSE SCALE AND ITS CONTROL. 21 summer. Under these circumstances much benefit will follow sum- mer spraying for the San Jose scale, but this work should be regarded as a temporary expedient to prevent undue increase of the insect until the more effective dormant treatment may be applied. Either the commercial or homemade lime-sulphur concentrate may be used for summer spraying (except on stone fruits), but they must be used in a much more dilute condition than during the winter. The di- lute lime-sulphur spray has come into very extended use asafungicide! and is used on pome fruits at the rate of 13 gallons of the concentrate, registering from 32 to 34 degrees on the Baumé scale, to 50 gallons of water. The use of the lime-sul- phur wash as a fungicide will constitute sufficient spray- ings for the scale, provided attention is given in spray- ing to coat, in addition to the leaves and fruit necessary in fungicidal work, also the limbs, branches, and twigs. Young scale insects from individuals which may have escaped the treatment have a decided tendency to mi- grate onto the fruit. The presence of these insects on the fruit is very objection- C able, especially on apples in- 7 tended for export trade, as a scale-infested fruit iS ex- Fig. 13.—Apparatus for determining specific gravity of cluded from entry by certain ica: >, specie gravity spindle; c, Baumé spindle. foreign governments, and is — (Original.) discriminated against by buyers generally. The influence of sulphur sprays used as fungicides in trees and foliage in checking the settling of young scales on the fruit is shown in Table II. These data were obtained by Mr. E. W. Scott, of the Bureau of Entomology, in the course of some experimental work during 1911 at Fennville, Mich. = 5 a a ~ ey eS eS ete & BS A: a a rea tothe eT BREESE ie 1 Quaintance, A. L., and Scott, W, M. The more important insect and fungous enemies of the fruit and foliage of the apple. U.S. Dept. Agr., Farmers’ Bul. 492, 48 p., 21 figs. 1912, 22 FARMERS’ BULLETIN 650. TABLE II.—Results of lime-sulphur sprays in preventing marking of fruit by the San Jose scale. araiier Number | Total | Percent- Est Treatments.1 Variety. of apples | f @Pples | number | age of un- 0. infested, | 20% of infested ‘| infested. | apples. | apples. 1 | Commercial lime sulphur, 14 to | Rhode Island Green- 137 1, 606 1, 743 92.13 50; sprayed May 12, 25, June ing. 14, July 25. ON \ hBare do ad ae BeBe Ree RRS eae ye See ale Bald wintaee... <= .c2-26 80 778 858 90. 67 3 | Home boiled lime sulphur, May | Greening...........- 79 3, 939 4,018 98. 03 12, 25, June 14, July 25. 4 jk eo dO etaen sce ceeem ease’ a. Bald winteee seas. c= 37 1,813 1, 850 98. 00 5 | Commercial lime sulphur, 1} to |..-.- dO... Fee ese neneane 13 298 311 95. 81 50; May 12, 25, June 14, July 25. 6 | Bordeaux mixture (3-4- 50), May | Greening.............. 843 1, 055 1, 898 55e58 12, 25, June 14, July 25. 7 fe bees dotlot. hss een ee Bald winSeee- - 22245258 525 500 1, 025 48.78 Sul MUmsprayedes. se. -peee eee Greenin geen... eee 796 805 1,601 50.28 OuieReee (6 (ca Re Paredes cit Aer. One Bald wintSee- + sca 809 190 999 19. 01 1 All treatments had 2 pounds of arsenate of lead to each 50 gallons of spray, except in case of plat 5, which had the poison in the application of May 12 only. Summer spraying of peach trees and other stone fruits for the scale may also be desirable because of ineffective work during the dormant period of the trees. Under such circumstances the self-boiled lime- sulphur mixture should be used, since the foliage of the peach will not stand the diluted lime-sulphur mixture previously indicated for the apple, pear, etc. This self-boiled lime-sulphur wash is made up according to quite a different formula from any of the washes hereto- fore mentioned, and has come into general use as a fungicide for the control of peach scab and brown-rot.'| Orchardists spraying for these troubles on peaches and other stone fruits may at the same time accomplish much in preventing the increase of the scale by thoroughly coating the limbs and branches of the trees while making the applica- tions to the foliage and fruit for the control of the fungous troubles mentioned. The self-boiled lime-sulphur wash may be made as follows Stone lime... .... eee -.-..... ee See. 2 SE pounds... 8 Sulphur (flour or flowers): .. -...... SE -pe sc beset ee dou 35 Aas Wateritowmakes -2>etees.-.... 2... SoBe ee ee ee gallons.. 50 The lime should be placed in a barrel and enough water poured on almost to cover it. As soon as the lime begins to slake the sulphur should be added, after first running it through a sieve to break up the lumps. The mixture should be stirred constantly and more water added as needed to form a thick paste at first and then gradually a thin paste. The lime will supply enough heat to boil the mixture several minutes. As soon as it is well slaked water should be added to cool the mixture and prevent further cooking. It is then ready to be strained into the spray tank, diluted, and applied. 1 Scott, W. M., and Quaintance, A. L. Spraying peaches for the control of brown-rot,scab and curculio, U.S. Dept. Agr., Farmers’ Bul. 440, 40 p, 14 figs. 1911, THE SAN JOSE SCALE AND ITS CONTROL. 23 The stage at which cold water should be poured on to stop the cooking varies with different grades of lime. Some limes are so sluggish in slaking that it is difficult to obtain enough heat from them to cook the mixture at all, while other limes become intensely hot on slaking, and care must be taken not to allow the boiling to proceed too far. If the mixture is allowed to remain hot 15 or 20 minutes after the slaking is completed the sulphur gradually goes into solu- tion, combining with the lime to form sulphids, which are injurious to peach foliage. It is therefore very important, especially with hot lime, to cool the mixture quickly by adding a few buckets of water as soon as the lumps of lime have slaked down. The intense heat, violent boiling, and constant stirring result in a uniform mixture of finely divided sulphur and lime, with only a very small percentage of the sulphur in solution. It should be strained to take out the coarse particles of lime, but the sulphur should be carefully worked through a strainer. The mixture can be prepared in larger quantities if desirable, say enough for 200 gallons at a time, making the formula 32 pounds of lime and 32 pounds of sulphur to be cooked with a small quantity of water (8 or 10 gallons) and then diluted to 200 gallons. COMMERCIAL POWDERED SULPHUR COMPOUNDS. Within the past: two or three years certain manufacturers have offered for sale, in a dry powdered condition, compounds of sulphur which are to be dissolved in water for the preparation of the spray. These compounds give promise of being satisfactory as scale washes, and if so, will undoubtedly meet with prompt favor with orchardists, since by their use there is a distinct saving in freight, and they are much more convenient in handling and storing. PETROLEUM-OIL SERIES. Under the heading “ Petroleum-oil series” are to be included kero- sene and crude petroleum, either pure or in emulsion, and the so- called miscible oils. Pure KEROSENE. Pure kerosene has been recommended to a greater or less extent for spraying trees badly infested with the scale, but it has never been very generally employed. There is no question of the efficiency of such an application in the destruction of the insects, but the great danger of injury to the plants precludes its general application. Treatments of pure kerosene should be made only to dormant trees and during bright days and should be applied through a nozzle with a very fine aperture. Only the minimum amount of kerosene necessary to cover the trees should be given, and care is necessary that the liquid does not puddle around the roots of the trees. 24 FARMERS’ BULLETIN 650. Pure Crupre PETROLEUM. Pure crude petroleum is used in identically the same manner as pure kerosene, and the same cautions as to its use should be remem- bered. The crude oil employed in the East is known as “insectide oil” and has a specific gravity of 43 to 45 degrees on the Baumé scale. KEROSENE Emutsion (Stock SoLuTION 66 PER Cent Orn). Kerosene emulsion is made after the following formula: Kerosene (coaliol aamp:oil). .... Gae 1.02 eee tee a. 2 gallons.. 2 Fish-oil soap or laundry soap (or 1 quart of soft soap)......-- pound... 4 Waker aoe ee rer... «2. - ioc See eat gallon.. 1 Fic. 14.—Bucket spray pump suitable for use in yards. (Author’s illustration.) Dissolve the soap in boiling water; then remove the vessel from the fire. Immediately add the kerosene and thoroughly agitate the mixture until a creamy solution results. The stock emulsion may be more conveniently made by pouring the mixture into the tank of a spray pump and pumping the liquid through the nozzle back into the tank for some minutes. The stock solution, if well made, will keep for some months, and is to be diluted before using. In order to make a 10 per cent spray (the strength for trees in foliage), add to each 1 gallon of the stock solution about 53 gallons of water. For 20 and 25 per cent emulsions (for use on dormant trees and plants), use, respectively, about 24 gallons and 13 gallons of water for each 1 gallon of stock emulsion. Agitate the mixture in all cases after adding the water. The preparation of the emulsion will be simplified by theuseof anaphthasoap. No heatwillthen berequired, as the kero- THE SAN JOSE SCALE AND ITS CONTROL. 25 sene will combine readily with the naphtha soap in water when thor- oughly agitated. Of naphtha soap, however, double the quantity given in the foregoing formula will be required, and soft or rain water should be used in making the emulsion. In regions where the water is “hard” this should first be broken with a little caustic potash or soda, such as common lye, before use for dilution, to prevent the soap from combining with the lime or magnesia present, thus liberat- ing some of the kerosene; or rain water may be employed. CrupDE PETROLEUM EMULSION. Crude petroleum emulsion may be prepared in identically the same way as described for kerosene emulsion, substituting crude petroleum for kerosene. The same dilutions for winter and summer Fig. 15.—Knapsack sprayer suitable for spraying Fic. 16.—Barrel sprayer suitable for orchard or sim- low-growing plants. (Author’s illustration.) ilar large-scale work. (Author’sillustration.) spraying should be made as prescribed for kerosene emulsion, but it should be noted that for summer treatments of trees in foliage the kerosene emulsion is preferable, as it is less likely to cause injury. MiscisLE Ons. ‘ Under the heading ‘miscible oils” are to be designated several proprietary preparations which are essentially petroleum oils with the addition of a vegetable oil and an alkali, to secure ready saponifica- tion with water. These come in concentrated solutions and the spray is prepared by adding a specified amount of water. In point of convenience they leave little to be desired. Miscible oils have come into use in place of kerosene or crude petroleum, either pure or in emulsions, and have a distinct usefulness as winter sprays about the same as have the concentrated lime-sulphur solutions. As has 26° FARMERS’ BULLETIN 650. been indicated, the petroleum oils are at times the cause of injury to twigs and fruit buds, in extreme cases killing the trees. It is a question of judgment whether, under conditions of severe scale infestation, the petroleum oils or the sulphur solutions should be used. The petroleum oils, on the whole, are more effective and the danger of injury from them is less to pome than to stone fruits. The practicability of making miscible oils at home has been investi- gated by Prof. C. L. Penny, and he has shown it to be entirely feasible, as detailed in the publications cited below.' Fic. 17 —Gasoline power spraying outfit for use in large orchards. (Original.) SOAP WASHES. Practically the only soap wash which has come into extended use against the San Jose scale is that made from fish oil. Fish-oil soap is used mostly on dormant trees, being employed at the rate of 2 pounds to the gallon of water. A potash fish-oil soap is preferable and should contain not more than 30 per cent of water. Soda soaps, while perhaps cheaper, will be 1 Penny. Charles L. Petroleum emulsions. Del. Agr. Col. Expt. Sta., Bul. 75, 39 p., June 18, 1906. Penny, Charles L. Miscible oils: How to make them. Penn. State Col., Bul. 86, 20 p., fig., March, 1908. THE SAN JOSE SCALE AND ITS CONTROL. a likely to solidify on cooling when used at the strength just indicated, and are hence forced through the spray-nozzle with difficulty. For spraying trees in foliage the soap should be used at the rate of 1 pound to 3 or 4 gallons of water, or somewhat weaker. SPRAYING APPARATUS. For the successful application of sprays to trees and plants infested ‘with the San Jose scale some form of spraying apparatus is necessary. For small plants, as low trees, ornamental hedges, etc., a bucket pump (fig. 14) or a knapsack pump (fig. 15) will be satisfactory. The barrel pump (fig. 16) will permit of more thorough work and will be suitable for orchards of some size. It may be placed in a wagon or cart or mounted on a sledge. For large commercial orchards the hand-power tank, or gasoline outfits, are, of course, employed. (See fig. 17.) It is quite practicable in case but a few trees in the yard are to be treated to apply the wash on the limbs and branches by means of a brush, or even with old cloths. Fish-oil soap is excellent in such cases. Severe pruning of the trees is usually desirable to simplify the work of treatment, and also to produce a new growth of noninfested wood. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1915 Di ice hk S.uC13.' UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS’ BULLETIN Wasuincton, D.C. ~ 657 May 6, 1915. =~ Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE CHINCH BUG.' By F. M. WEBSTER, In Charge of Cereal and Forage Insect Investigations. INTRODUCTION. Few insects, and certainly no other species of the natural order to which this one belongs, have been the direct cause of such enormous pecuniary losses as the chinch bug (fig. 1). No other insect native to the Western Hem- isphere has spread its devastating hordes over a wider area of country (see maps, figs. 6 and 7) with more fatal effects to the staple grains of North America than has this one. Were it not for the extreme susceptibility of the very young to destruction by drenching rains, and the less, though not insignificant, fatalities to both the adults and young dur- ing rainy seasons attributed to the parasitic fungus S porotrichum globuliferum Speg., the ll ghana ee Gums practice of raising grain year after year on — teucopterus): Adult of long- the same areas, as is followed in some parts of Winged form, much enlarged. ines (Author’s illustration.) the United States, would become altogether unprofitable. Some of this insect’s own habits, emphasizing as they do the effects of weather conditions, are among the most potent influences that serve to hold it within bounds by giving its tendency to excessive increase a decidedly spasmodic character. 1 Blissus leucopterus Say; order Hemiptera, family Lygeide. Notre.—This bulletin describes the forms and stages of the chinch bug, its habits and natural enemies, and suggests methods of preventing its ravages. It will be of general interest wherever this pest prevails. 82461°—Bull. 657—15——1 9 FARMERS’ BULLETIN 657. DESCRIPTIONS OF THE DIFFERENT STAGES. THE EGG. The average length of the chinch bug’s egg (fig. 3, a, 6) is three one-hundredths of aninch. In shape it is enitovsl ie diameter being scarcely one-fifth the length. The top is squarely docked and surmounted with four small, rounded tubercles near the center. When Fig. 2.—Chinch bug: Adults of short-winged form. Much enlarged. (Author’s illustration.) newly deposited the egg is pale or whitish and translucent, but with age it acquires an aniber color and finally shows the red parts of the embryo within, especially the eyes toward the tubercled end. The size increases somewhat after deposition, and the length will some- times reach nearly four one-hundredths of an inch. THE LaRVAL, OR NYMPHAL, STAGES. The newly hatched larva, or nymph (fig. 3, c, d), is pale yel- low, with simply an orange stain on the middle of the three larger abdominal — joimts. The form scarcely differs from that of the mature bug, be- ing but slightly more elon- gate; but the tarsi have only two joints, and the head is relatively broader and more rounded, while the joints of the body are subequal, the prothoracic Fic. 3.—The chinch bug: a, b, Eggs; c, newly hatched larva, Teen og eo eee y avec HEERLEDS ginnsogs lan a eee longer than any of the rest. dicated at sides; h, enlarged leg of perfect bug; j, tarsus of The red color soon per- Same still more enlarged; i, proboscis or beak, enlarged. (From Riley.) vades the whole body, ex- cept the first two abdominal joints, which remain yellow ish, and the legs and antenne, which remain pale. ie the first molt (fig. 3, e) the red becomes bright vermilion, contrasting strongly with the pale band across the middle of the Zz THE CHINCH BUG. S body; the prothoracic joint is relatively longer, and the metathoracic shorter. The head and prothorax are dusky coriaceous; two broad marks on the mesothorax, two smaller ones on the metathorax, two on the fourth and fifth abdominal sutures, and one at the tip of the abdomen, are generally visible, but sometimes obsolete; the third and fourth joints of the antenne are dusky, but the legs are still pale. After the second molt (fig. 3, f) the head and thorax are quite dusky ; the abdomen duller red, but the pale transverse band is still dis- tinct; the wing pads become apparent; the members are more dusky ; there is a dark-red shade on the fourth and fifth abdominal joints, and ventrally a distinct circular dusky spot covering the last three joints. In the last-stage larva or nymph (fig. 3, g), sometimes called the “pupa,” all the coriaceous’ parts are brown-black, the wing pads extend almost across the two pale abdominal joints, which are now more dingy, while the general color of the abdomen is dingy gray; the body above is slightly pubescent, the members are colored as in the mature bug, the three-jointed tarsus is foreshadowed, and the dark horny spots at the tip of the abdomen, both above and below, are larger. THE ADULT FORMS. There are two forms of the fully developed insect, but it is not known that the young of these two forms differ in any respect. One of these forms, the one originally described, is known as the long- winged form and is the only form that occurs over most of the country between the Rocky Mountains and the Allegheny Mountains. This form is illustrated in figure 1. The second form is much like the first, with the exception of the wings, which are more or less abbreviated, as shown in figure 2. This form occurs along the seacoasts, and in the East extends inland along the lower lakes to northern Illinois. It is not abundant, however, west of a line drawn from Toledo, Ohio, to Pittsburgh, Pa. Through- out the territory in which this short-winged form is found there are also intermingled with them individuals of the long-winged form. Both of these forms may be described as black, with numerous hairs, also black; the upper wings are whitish, with a black spot on each, and the under wings are white. They are about one-fifth of an inch or less in length and may be easily recognized by the accom- panying illustrations (figs, 1, 2, 3, h, 7, 7). SEASONAL HISTORY. Over the territory covered by the long-winged form, as previously given, the insect has two generations each year. The young of the first generation appear in May and June, and those of the second generation in August and perhaps as late as September. The adult 4 FARMERS’ BULLETIN 657. insects (figs. 1, 2) pass the winter among clumps of broom sedge,! and where this does not occur in sufficient abundance, among matted grass, fallen leaves, and other rubbish, coming forth from hiding in spring, spreading to the grain fields, where they deposit their eggs, and dying soon afterwards. The young (fig. 3, ¢) hatching from these eggs cluster upon the plants and begin at once to feed upon the juices. Figure 4 illustrates a corn plant with the chinch bugs clustering upon it. The egg-laying season extends over a considerable period, and Fic. 4.—Corn plant 2 feet tall infested with chinch bugs. ‘(Author’s illustration.) chinch bugs of all ages, sizes, and colors may be found intermingled. By midsummer the majority of the first generation have reached the adult stage, soon after which the eggs are deposited for the second generation, nearly all individuals reaching their full development by late fall or early winter. This second generation develops and matures on corn, millet, kafir, and similar crops. It must be remembered that each female of the species is capable of laying from 1 to 500 eggs, and she will scatter them during a period 1 Andropogon spp. THE CHINCH BUG. 5 of from two to three weeks. The time required for the eggs to hatch is from about ten days to three weeks, and it requires about forty days for the young to become fully developed after hatching from the egg. In the eastern portion of the country, where the short-winged form (fig. 2) prevails, it is not certain that there is more than a single generation annually. This short-winged form differs very greatly in its habits from the long-winged form, the first passing the winter in the meadows, which it usually attacks in preference to grain fields, whereas during the period known as the Indian summer the developed bugs of the long-winged form (fig. 1) may be observed flying about, evidently searching for winter quarters. With the short-winged form these migrations to and from the places of hibernation are impossible, the insects being totally incapable of flying. A Fig. 2.— Tineola biselliella: Moth, larva, cocoon, and were scavengers in their earliest emipty pupa'skin, Enlarged. (From Riley.) association with man. The larva of this moth constructs no case, but spins a silky, or more properly cobwebby, path wherever it goes. When full grown it builds a cocoon of silk, intermixed with bits of wool, resembling somewhat the ease of pellionella, but more irregular in outline. Within this it undergoes its transformation to the chrysalis, and the moth in emerg- ing leaves its pupal shell projecting out-of the cocoon as with the pre- ceding species. THE TAPESTRY MOTH. The tapestry moth? (fig. 3) is rare in the United States. It is much larger than either of the other two species, measuring three- fourths inch in expansion of wings, and is more striking in coloration. The head is white, the basal third of the forewings black, with the ex- terior two-thirds of a creamy white, more or less obscured on the middle with gray; the hind wings are pale gray. This moth normally affects rather coarser and heavier cloths than the smaller species and is more apt to occur in carpets, horse blankets, and 1 Sitotroga cerealella Oliv. 2 Trichophaga tapetzella L. 6 FARMERS’ BULLETIN 659, tapestries than in the finer and thinner woolen fabrics. It also affects felting, furs, and skins, and is a common source of damage to the woolen upholstering of carriages, being rather more likely to occur in carriage houses and barns than in dwelling houses. Its larva enters directly into the material which it infests, constructing burrows or galleries, which it lines more or less completely with silk. Within these galleries it is protected and concealed during its larval life, and later undergoes its transfor- mations without other protection than that afforded by the gallery. Fic. 3.—Trichophaga tapetzella: Adult moth. En- The damage is due as much or pepe eee te more to its burrowing than to the actual amount of the material consumed for food. One of the parasites, Apanteles carpatus Say, reared from Tinea pel- lionella, has also been reared from the tapestry moth at St. Louis, Mo. REMEDIES. There is no easy method of preventing the damage done by clothes moths, and to maintain the integrity of woolens or other materials which they are likely to attack demands constant vigilance, with fre- quent inspection and treatment. In general, they are likely to affect injuriously only articles which are put away and left undisturbed for some little time. Articles in daily or weekly use, and apartments fre- quently aired and swept, or used as living rooms, are not apt to be seri- ously affected. Carpets under these conditions are rarely attacked, except sometimes around the borders, where the insects are not so much disturbed by walking and sweeping. Agitation, such as beat- ing, shaking, or brushing, and exposure to air and sunlight, are old remedies and still among the best at command. Various repellents, such as tobacco, camphor, naphthaline cones or balls, and cedar chips or sprigs, have a certain value if the garments are not already stocked with eggs or larvee. The odors of these repellents are so disagreeable to the parent moths that they are not likely to come to deposit their eggs as long as the odor is strong. As the odor weakens the protection decreases, and if the eggs or larve are already present, these odors have no effect on their development; while if the moths are inclosed with the stored material to be protected by these repellents, so that they can not escape, they will of necessity deposit their eggs, and the destructive work of the larve will be little, if at all, restricted. After woolens have been given a vigorous and thorough treatment and aired and exposed to sunlight, however, it is of some advantage in packing them away to inclose with them any of the repellents men- tioned. Cedar chests and wardrobes are of value in proportion to the ~. . THE TRUE CLOTHES MOTHS. | freedom of the material from infestation when stored away; but, as the odor of the wood is largely lost with age, in the course of a few years the protection greatly decreases. Furs and such garments may also be stored in boxes or trunks which have been lined with heavy tar paper used in buildings. New papering should be given to such receptacles every year or two. Similarly, the tarred paper moth bags obtainable at dry-goods houses are of some value; always, however, the materials should first be subjected to the treatment outlined above. To protect carpets, clothes, and cloth-covered furniture, furs, etc., these should be thoroughly beaten, shaken, brushed, and exposed as long as practicable to the sunlight in early spring, either in April, May, or June, depending on the latitude. The brushing of garments is a very important consideration, to remove the eggs or young larve which might escape notice. Such material can then be hung away in clothes closets which have been thoroughly cleaned, and, if neces- sary, sprayed with benzine about the cracks of the floor and the baseboards. If no other protection be given, the garments should be examined at least once a month during summer, brushed, and, if neces- sary, exposed to the sunlight. It would be more convenient, however, so to inclose or wrap up such material as to prevent the access of the moths to it, after it has once been thoroughly treated and aired. This can be easily effected in the case of clothing and furs by wrapping tightly in stout paper or inclos- ing in well-made bags of cotton or linen cloth or strong paper. Dr. L. O. Howard has adopted a plan which is inexpensive, and which he has found eminently satisfactory. For asmall sum he secures a num- ber of the large pasteboard boxes, such as tailors use, and in these packs away all winter clothing, gumming a strip of wrapping paper around the edge, so as to seal up the box completely and leave no cracks. These boxes with care will last many years. With thorough preliminary treatment it will not be necessary to use the tar-impreg- nated paper sacks sold as moth protectors, which may be objection- able on account of the odor. In the case of furniture or carriages, covered or lined with woolen cloth, stored or left unused for the summer, examination and thor- ough brushing should be given at least monthly. Spraying monthly with benzine or naphtha or sponging with dilute corrosive sublimate has been recommended, but due regard should be given to the inflammability of these sprays and to the poisonous nature of the corrosive sublimate. The method of protection adopted by one of the leading furriers of Washington, D. C., who also has a large business and experience in storing costly furs, etc., is practically the course already outlined. Furs when received are first most thoroughly and vigorously beaten with small sticks, to dislodge all loosened hair and the larve or moths. 8 FARMERS’ BULLETIN 659, They are then gone over carefully with a steel comb and packed away in large boxes lined with heavy tar roofing paper, or inclosets similarly lined with this paper. An examination is made every two to four weeks, and, if necessary at any time, any garment requiring it is rebeaten and combed. During many years of experience in this climate, which is especially favorable to moth damage, this merchant has prevented any serious injury from moths. COLD STORAGE. The best method of protection, and the one now commonly adopted by dealers in carpets, furs, etc., is cold storage. In all large towns anyone can avail himself of this means by patronizing storage com- panies, and safety will be guaranteed. The most economical degree of cold to be used as a protection from clothes moths and allied insects destructive to woolens and furs has been definitely determined by the careful experiments carried out at the instance of Doctor Howard by Dr. Albert M. Read, manager of a large storage warehouse company in Washington, D. C. These experiments demonstrated that a temperature maintained at 40° F. renders the larval or other stages of these insects dormant and is thor- oughly effective. The larve, however, are able to stand a steady temperature as low as 18° F. without apparently experiencing any ill results. Doctor Read’s experiments have extended over two years, and his later results as reported by Doctor Howard are very interest- ing. They have demonstrated that while a temperature kept uni- formly at 18° F. will not destroy the larve of Tineola biselliella or of the black carpet beetle,’ ‘‘an alternation of a low temperature with a comparatively high one invariably results in the death of the larve of these two insects. For example, if larve of either which have been kept at a temperature of 18° F. are removed to a temperature of 40° to 50° F., they will become slightly active and, when returned to the lower temperature and kept there for a little time, will not revive upon a retransfer to the warmer temperature.”’ It is recommended, therefore, that storage companies submit goods to two or three changes of temperature as noted before placing them permanently in an apartment kept at a temperature of from 40° to 42° F. The maintenance of a temperature lower than the last indi- cated is needless and a wasteful expense. Where the cost of cold storage is not an item to be seriously considered, the adoption of this method for protection of goods during the hot months is strongly recommended. 1 Attagenus piceus Oliv. f . f WASHINGTON : GOVERNMENT PRINTING OFFICH : 1915 te o% FARMERS’ BULLETIN WasuinctTon, D. C. 662 May 1), 1915 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE APPLE-TREE TENT CATERPILLAR.’ By A. L. QUAINTANCE, In Charge of Deciduous Fruit Insect Investigations. INTRODUCTION. The conspicuous, unsightly nests or tents of the apple-tree tent caterpillar (fig. 1) are familiar objects in the spring in trees along roadways, streams, and fences, in neglected orchards, and elsewhere. The gregarious caterpillars construct the tents for their protec- tion, and these, at first small, are gradually enlarged as the larvee grow, often to a foot or more in height and diameter, the size varying with the number of individuals in the colony. The caterpillars feed upon the foliage of the trees, stripping the leaves from the limbs adjacent to the nest, and if there be several colonies in a tree, as is frequently the case during periods of abundance, the foliage may be quite destroyed, leaving the branches as bare as in midwinter (fig. 2). DISTRIBUTION AND FOOD PLANTS. The tent caterpillar is a native American species occurring quite generally in the United States from Canada south to Florida and westward about to the Rocky Mountains. From the Rockies to the Sierras, according to Dyar, the species is replaced by another of the same genus,? which ranges from Canada to Mexico, and this latter form in the Pacific Northwest is replaced by still another species. The tent caterpillar has been a troublesome pest from the earliest times. As stated by Fitch, its injuries in Massachusetts in the years 1646 and 1649 led the early settlers to term these ‘caterpillar years.”” At rather long and irregular intervals the caterpillars have been excessively abundant in different parts of their range, but more 1 Malacosoma americana Fab. 2 Malacosoma fragilis Stretch. 3 Malacosoma pluvialis Dyar. 84973°—Bull. 662—15——1 2 FARMERS’ BULLETIN 662. FiG. 1.—Nest and larvee of apple-tree tent caterpillar in crotch of wild cherry tree. (Original.) THE APPLE-TREE TENT CATERPILLAR. 8 particularly in the New England States. This species was among the first to receive attention by the early American entomologists, and the principal features in its life and habits have been known for many years. Throughout its extended distribution the insect is likely to be abundant each year in one or more localities and often over a considerable territory. Scattered nests are to be found usu- ally during any spring, although in some seasons these are but little in evidence. Fic. 2.—Nests of apple-tree tent caterpillar in wild cherry tree which the larve have defoliated. (Original.) The favorite food of the tent caterpillar is the wild cherry, and this is probably its native food plant. Next to the wild cherry the apple is apparently preferred. In the absence of its favorite food, or under special conditions, it attacks many other plants, as plum, peach, thorn, pear, rose, and other members of this group, as also beech, witch-hazel, elm, maple, and various species of willows, oaks, and poplars. During periods of unusual abundance trees are more or less completely defoliated, and at a time when they most need the leaves for their growth or for the development of the fruit, and they are materially weakened, though rarely killed. 4 FARMERS’ BULLETIN 662, DESCRIPTION AND LIFE HISTORY. THE EGG. Eggs are deposited in masses or belts encircling the smaller twigs, as shown in figure 3. Different egg masses may vary from one-half to three-fourths of an inch in length and contain from 150 to 250 eggs. The average number of eggs in several egg masses counted by Prof. V. H. Lowe on peach and apple was about 223 each. Each egg belt is deposited by an in- dividual female and ordinarily rep- resents the entire number which she wil deposit. Eggs are placed on end, cemented closely together, the whole oval-shaped mass being finally cov- ered with a layer of light-brown frothy glue, whichsoon be- comes tough, brit- tle, and glistening. Eggs are deposit- ed by the moths by early midsum- mer, or earlier in the South, the em- bryonic larve de- veloping so that by fall they are prac- tically full grown, Fia. 3.—Egg masses of apple-tree tent caterpillar. Slightly enlarged. although remaining (Original.) within the egg until the following spring. With the coming of a warm spell the larvee escape by gnawing through their eggshells, often before there is foliage out for food, and under these circumstances they may feed upon the glutinous covering of the egg mass. THE LARVA. In the presence of food the larve begin the formation of their nest in about two days from hatching, usually selecting the crotch formed by two limbs and ordinarily one that is not far from the egg mass. The caterpillars are sociable, those from one egg mass inhabit- ing one nest and feeding together upon the adjacent leaves. If two ege masses happen to be deposited close together, as on the same or THE APPLE-TREE TENT CATERPILLAR, 5 adjacent twigs, the resulting caterpillars may unite in one nest. Wherever they go each larva spins a thread of silk, the young indi- viduals hanging suspended from a silken thread when they drop, as do the cankerworms and many other larve. The nests, at first small and affording but little shelter, are gradually enlarged as the cater- pillars grow and soon furnish ample protection. Upon close exami- nation the nests of this species will be found to be made up of layers of silk, with room for the larve between the layers. According to Fitch these layers are the result of the caterpillars’ habit of lying on the outside of the nest during bright weather, the few restless indi- viduals crawling back and forth over the resting mass, spinning silk Fig. 4.—Full grown apple-tree tent caterpillar. About twice natural size. (Original.) as they go, soon forming a new layer. During rainy and cloudy weather the larve remain mostly within the nest, but when the weather is favorable they feed at regular intervals; according to Fitch, in the morning, in the afternoon, and again during the night. Upon becoming nearly full grown the larve wander singly away from the nest, feeding upon such plants as come to hand. This wandering habit preparatory to pupation results in the scattering of the pupe and greatly increases the chances of their escape from destruction from their numerous natural enemies. When full grown the caterpillars are about 2 inches long, cylin- drical, deep black, with a white stripe along the back, and lateral markings, as shown in figure 4. On each side is a row of oval pale- 84973°—Bull. 662—15 2 6 FARMERS’ BULLETIN 662. blue spots, one on the middle of each segment, and on the anterior side of each is a broader, deep velvety black spot. The body-is sparsely clothed with fine, soft, yellowish hairs of varying length, thickest perhaps toward the anterior end, where they project forward over the black-colored head. In about six weeks from hatching the larve become full grown and wander away from the nest, as stated, in search of suitable places for pupation. THE COCOON. The larvee select for pupation any convenient, more or less secluded place, as under loose bark, in grass or brush under trees, along fences, etc. If close to outbuildings the larve often make their cocoons in Fia@. 5.—Cocoon and pupa of apple-tree tent caterpillar. About twice natural size. (Original.) the angles along the sides, in window casings, etc. The cocoon, shown in figure 5, at the left, is oval in shape, about 1 inch long, and composed exteriorly of coarse, loose, whitish threads of silk surrounding the tougher parchmentlike lining. The silk of the cocoon is intermixed with a yellow powdery substance, which readily comes off when disturbed. Cocoons are made more or less singly, although in suitable shelter near the nest several may be found spun together, the larve taking advantage of the same protection. Co- coons are frequently found within the nest, although these will usually prove to be parasitized. THE PUPA. Within the cocoon the larva changes to a short, oval, brownish pupa, as shown in figure 5, at the right. This stage lasts about three weeks, the time varying somewhat; then the moth appears. THE APPLE-TREE TENT CATERPILLAR. vi THE ADULT. -Both sexes of the tent-caterpillar moth are shown in figure 6, the female to the right. These are dull reddish-brown, stout-bodied moths, with a wing expanse in the females of about 1.5 to 2 inches, and in the males of from 1.2 to 1.3 inches. Obliquely across the forewings of each sex are two nearly parallel whitish lines, as shown in the illustration. Soon after emergence the sexes mate, and eggs are deposited on limbs and twigs. There is only one generation each year, the insects existing in the egg stage throughout the remaining summer and fall and through the winter, the young larve coming from the eggs in early spring and forming their nests, or tents, as stated. FiG. 6.—Moths of apple-tree tent caterpillar; male at the left. Slightly enlarged. (Original.) NATURAL ENEMIES. This species is subject to attack by numerous parasitic and preda- ceous enemies, which undoubtedly exert an important influence in keeping it reduced. Very minute, four-winged flies of the order Hymenoptera deposit their eggs within those of the tent caterpillar moth, the resulting larve or grubs finding sufficient food for their growth and development to parent flies. Three egg parasites have been recorded for this species.t Larye and pup furnish food for a large number of parasites and hyperparasites. Thus W. F. Fiske ? records a total of some 24 species of insects which directly or indirectly feed upon the tent caterpillar. Eighteen primary parasites have been recorded from the larva and pupa. 1 Telenomus clisiocampae Riley, Pteromalus sp., and Platygaster sp. 2 Tech. Bul. No. 6, N. H. College Agric. Exp. Sta., p. 2 (1903). 2 Itoplectis conquisitor (Say), Itoplectis annulipes (Brullé), Pimplidea pedalis (Cress.), Iseropus inquisi- toriella (Dalla Torre), Limnerium fugitivum Say, A meloctonus clisiocampae Weed, Anomalon exile Prov., Anomalon anale Say, Spilocrytus extrematis Cress., A panteles congregatus var. rufocoralis Riley, A panteles clisiocampae Ashm., Rhogas intermedius Cress., Hadrobracon hopkinsi Vier. (mentioned in the reference given above as Bracon gelechix Ashm., an erroneous determination), Diglochis omnivorus Walk., Miotropis clisiocampae Ashm., Theronia melanocephala Brullé (?)—all Hymenoptera—and the dipteron Frontina frenchit Will, 8 FARMERS’ BULLETIN 662. Among predaceous insects are several species of ground beetles which are said to feed upon the larve, among them Calosoma scruta- tor Fab. Among the Hemiptera Mr. A. H. Kirkland has observed several species of Podisus' and the reduviid, Diplodus luridus Stal, attacking the larve. According to Prof. Bruner, Podisus spinosus Dall. and Perillus claudus Say also are enemies of the caterpillar. While most birds as a rule do not feed on hairy larve such as the tent caterpillar, yet several species are known to include this insect in their diet, as the black-billed and yellow-billed cuckoos, the blue- jay, and, according to Mr. E. H. Forbush, the crow, chickadee, Balti- more oriole, red-eyed vireo, chipping sparrow, and yellow warbler. Kirk- land states that the common toad feeds greedily on tent caterpillars, he having found in their stomachs the remains of from 15 to 20, and in one instance 37 of these larvee. The caterpillars are also subject to destruction by a bacterial disease, especially when they become grown Fic. 7.—Itoplectis in the act of ovipositingon OT nearly SO, and sick, sluggish indi- cocoon of apple-tree tent caterpillar. En- viduals may often be observed lying larged. (After Fiske.) F outside at full length on the nest. Larve killed by this disease are soft-bodied, the skin easily rupturing and permitting the escape of the liquid, decomposed body contents. METHODS OF CONTROL. REMOVAL OF USELESS TREES. As has been stated, the unsightly nests of the tent caterpillars are especially apt to be found on wild cherry, apple, and other trees grow- ing along roadsides, fences, and elsewhere. In most cases such trees could doubtless be removed without disadvantage, and their removal would greatly reduce the numbers of this pest by lessening theirfavorite food supply. COLLECTING THE EGGS. During the dormant period of trees, when the leaves are off, the egg masses are fairly conspicuous, and with a little practice may be readily found; it is then that the twigs bearing them should be cut off and burned. Trees infested with larve during the early part of the year, or those in the immediate vicinity, are perhaps more likely to be chosen by the parent moth for the deposition of her eggs, and such trees at least should be searched if it is not practicable to extend 1 Podisus placidus Uhl., P. modestus Dall., and P. serieventris Uhl. THE APPLE-TREE TENT CATERPILLAR. 9 the work to the orchard as a whole. This work may be combined with pruning to good advantage, and a lookout should be kept not only for the eggs of this insect but for the eggs and cocoons of other injurious species which pass the winter on the trees. Practical illustrations of what may be accomplished in collecting the egg masses of this species have recently been reported by Prof. Myron A. Cobb, of the Central State Normal School at Mount Pleasant, Mich. The tent caterpillar was present in unusual numbers in north- western Michigan during the season of 1913, and egg masses were eénsequently very much in evidence the following winter (1913-14). Through circulars issued to the rural schools, the school children were interested in the collection of egg masses, with surprisingly successful results. A special “apple-tree tent-caterpillar week’’ was desig- nated and other means adopted to carry out effectively the campaign against this insect. The total number of egg masses collected through the work of the school children was variously estimated at from one million to several million. A few specific examples may be cited. In Wexford County 250,000 egg masses were reported to have been collected. At Greilickville, 20,443; Bungham School, Grand Tray- erse County, 17,940. At Elk Rapids the Business Mens’ Association offered prizes for the greatest number of egg masses destroyed. This also was done at Old Mission and 65,784 egg masses were collected, the prize going to Carl Ostlind for 11,044 egg masses taken. Since each egg mass contains on the average some 250 eggs, the benefits from this work may readily be calculated. There are great possibilities for the accomplishment of much effec- tive work in the control of this and other insect pests by the enlist- ment of the services of children in rural schools, and the work is a practical application of science for the benefit of agriculture. DESTROYING THE CATERPILLARS. Neglect to search out the egg masses during the winter will result in the appearance of the larve about the time the trees are putting forth foliage. The nests, at first small, are soon so increased in size as to attract attention. If the caterpillars are destroyed as soon as the small nests are detected, this will prevent further defoliation of the trees, and the rule should be adopted to destroy them promptly as soon as discovered. In this work either of two practices may be adopted, namely, destruction by hand or with a torch. When in convenient reach, the nests may be torn out with a brush, with gloved hand, or otherwise, and the larve crushed on the ground, care being taken to destroy any caterpillars which may have remained on the tree. The use of a torch to burn out the nests will often be found con- venient, especially when these occur in the higher parts of trees. An asbestos torch, such as is advertised by seedsmen, will be satisfactory, or one may be made simply by tying rags to the end of a pole. The asbestos or rags are saturated with kerosene and lighted and the 10 FARMERS’ BULLETIN 662. caterpillars as far as possible cremated. Some caterpillars, however, are likely to escape, falling from the nest upon the application of the torch. In using the torch great care is necessary that no important injury be done the tree; it should not be used in burning out nests except in the smaller branches and twigs, the killing of which would be of no special importance. Nests in the larger limbs should be destroyed by hand, as the use of the torch may kill the bark, resulting in permanent injury. SPRAYING WITH ARSENICALS. Tent caterpillars are readily destroyed by arsenicals sprayed on foliage of trees infested by them. Dr. H. 'T. Fernald’s careful experi- ments and those of Prof. Lowe in determining the amount of poison necessary to kill the caterpillars show that the latter are very sensi- tive and are killed in from two to three days by the use of Paris green at the rate of 1 pound to 300 or 400 gallons of water. Orchards or trees sprayed with arsenicals in the spring for the codling moth, cankerworms, or similar insects will be kept practically free from tent caterpillars, and this species rarely requires attention at the hands of the up-to-date commercial fruit grower. It will be troublesome in the scattered trees around the home or in the small orchard which is not regularly sprayed. On such trees the nests will likely be in evidence every spring, and during occasional years the caterpillars may be excessively abundant, completely defoliating the trees. Even in the small home orchard of a dozen or more trees it will be found highly profitable to adopt a system of spraying which will control not only tent caterpillars but such serious pests as the cod- ling moth, cankerworms, and various bud and leaf feeding insects, and will greatly reduce injury from the curculio. Any of the arsenical insecticides may be used, as Paris green, Scheele’s green, arsenate of lead, etc. The first two are used at the rate of 1 pound to 150 or 200 gallons of water, and the last at the rate of 2 pounds to 50 gallons of water, the milk of lime obtained by slaking 2 or 3 pounds of stone lime being added to neutralize any caustic effect of the arsenical on the foliage. Preferably, however, the poisons should be used in dilute lime-sulphur wash or Bordeaux mixture, thus effecting a combination treatment for insects and fungous diseases. On stone fruits, such as cherry, peach, and plum, arsenicals are likely to cause injury to foliage and must be used with caution. Onsuch trees the arsenate of lead is preferable to the arseni- cals, as it is less injurious to foliage, and on all trees sticks much better. In spraying for the tent caterpillar only, applications should be made while the caterpillars are yet small, as these succumb more quickly to poisons than those more nearly full grown, and prompt treatment stops further defoliation of the trees. WASHINGTON : GOVERNMENT PRINTING OFFICE ; 1915 UNITED STATES DEPARTMENT OF AGRICULTURE 2 FARMERS ¢ BULLETIN WasuineTon, D.C. 668 May 26, 1915 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE SQUASH-VINE BORER.’ By F. H. Currrenven, In Charge of Truck Crop and Stored Product Insect Investigations. GENERAL APPEARANCE AND METHOD OF WORK. One of the most troublesome of the many enemies of squashes, pumpkins, and other cucurbits is the squash-vine borer. In many localities this spe- cies surpasses all’ other squash in- sects in point of injuriousness. Damage is due to the larve bor- ing through the . stems, causing them to rot at the affected points and become sev- ered from the ee ee eee: eee ing the vine as to full-grown larva, in situ in vine; e, pupa; f, pupal cell. All one-third cause the leaves larger than natural size. (Author’s illustration.) to wilt and the plant to die. The presence of the borer feeding within the stem is not apparent at the commencement of the attack, but soon becomes manifest through the presence of the coarse yellowish excre- ment which it forces from its burrow in the stem and which accumu- lates on the ground beneath, as well as by the sudden wilting and dying down of the leaves. Wilting occurs soon after the larve have made 1 Melittia satyriniformis Hbn.; order Lepidoptera, family Sesiidee. In early publications this species was generally known as Melittia ceto, or cucurbitz. NotE.—This bulletin is a revision of Circular No. 38 of the Bureau of Entomology, U. S. Department of Agriculture. 88373°—Bull. 668—15 2 FARMERS’ BULLETIN 668. considerable growth within. From one to half a dozen or more larvee inhabit a stem, and often upward of forty individuals have been taken from a single plant; indeed, one grower has stated that he once cut ‘(142 larve from a single vine.”’ The larve work with great rapidity and in a very short time are-able to injure a plant so that no fruit will mature. Injury is most noticeable near the base of the stems, where in course of time the vine becomes severed from the roots and the whole vine dies. The parent of this insect is a beautiful, medium-sized moth. The forewings are opaque, lustrous ofive-brown in color, with metallic green reflections, and expand from less than an inch to nearly an inch and a half. The hindwings are transparent and veined as shown in the accompanying illustration of the male (fig. 1, a). The abdomen is conspicuously marked with orange or red, black, and bronze, and the hind legs are frmged with long hairs—red or orange on the outer surface and black inside. The natural position of the moth when at rest is shown by the figure of the female (0d). DISTRIBUTION. As far as known, the squash-vine borer is a native of the Western Hemisphere, and widely distributed and injurious in the United States practically wherever squashes are cultivated. Available rec- ords and examination of material in the collection of the U.S. National Museum show that it has a range embracing territory from the New England States and Canada, in the north, to the Gulf States south- ward, and westward to the region beyond the Missouri River, which comprises the major portion of the Carolinian and Austroriparian areas of the Upper and Lower Austral life zones and a portion also of ° the Transition zone. Injury has been observed to be particularly severe in recent years on Long Island and in New Jersey, Delaware, Maryland, Virginia, and the District of Columbia, in the East, and in Kansas and Nebraska in the West. Other States in which injury has been noted include Maine, Massachusetts, Connecticut, Rhode Island, Georgia, Alabama, Mississippi, Louisiana, Iowa, and Michi- gan. It is evidently of tropical origin, and occurs in Mexico, where it is also widely distributed, and in Guatemala, Panama, Venezuela, Argentina, and the lower Amazon. FOOD HABITS. The vines of squash and pumpkin form the chief food supply of this insect, but occasionally it attacks also the gourd, muskmelon, and cucumber. It does not, however, in the writer’s experience, infest melons and cucumbers when the other preferred crops are available. The larve bore through the stems from the roots to the base of and even through the leaf stalks, and young larve may be found even in THE SQUASH-VINE BORER. $ the larger veins, into which they bore when the eggs have been placed in such locations, and often attack the fruit. They also penetrate gourds so hard that it is difficult to cut into them with a sharp knife. Larve have been observed on the wild balsam apple,t which is probably a natural food plant. Injury is greatest to Hubbard, marrow cymlings, and other late varieties of squash, and is apt to be more acutely felt in small gardens than where crops are grown for market. Even if the plant survives attack it may not bear fruit, and often the grower loses a large pro- portion of his crop year after year. Not infrequently entire crops are destroyed, and still more frequently every plant in a field is attacked freely. NATURAL HISTORY. This species is injurious only in the larval form. Although the larve are familiar objects to squash growers, the moths are not gen- erally recognized as the parents of these pernicious borers. The moths, unlike most others, fly only during the daytime and in the heat of the day. Toward twilight they become less active and may be seen sitting quietly on the leaves of their host plants. Both when in flight and when at rest the moths are singularly wasp- like in appearance. TIME OF APPEARANCE OF THE MOTH. Approximately it may be stated that the moth appears as soon as the vines are sufficiently advanced to serve for oviposition and the subsequent subsistence of the borer larve within their stems. Indications are that as far south as the District of Columbia the moths make their first appearance in the field some time in May, "or, at least, early in June, as larvee nearly matured have been found by the middle of July. In New Jersey, according to Dr. J. B. Smith, the moths are abroad at or soon after the beginning of June; on Long Island, from the middle to the last of June. In Massachusetts, according to Harris, they appear about the plants the second week in July. We thus have considerable variation in time of earliest appearance, dependent upon season and locality—a variation to be expected in a species of so wide a range. THE EGG AND OVIPOSITION. The eggs, which are oval and dull red in color, are laid upon all parts of a plant, from the roots to the buds and petioles, but chiefly along the stems, although in some varieties of squash, it is said, nearer the base of the stem than otherwise. Oviposition is very rapid, the moth flitting from hill to hill, leaving an egg in each. A single moth may lay as many as 212 eggs. The eggs hatch in from six to fifteen days after they are deposited, and the larve are said to attain full 1 Echinocystis lobata. 4 FARMERS’ BULLETIN 668. growth four or more weeks later. This period will undoubtedly vary in different temperatures, according to the season of the year when oviposition takes place. Eggs are shown a little larger than natural at ¢ of figure 1, and much magnified at @ and 6 of figure 2, ¢ showing the sculpture. THE LARVA. The larva is a soft, whitish, grublike caterpillar of nearly cylin- drical form, with a small dark head and a few very sparse hairs on each segment. Larve in the earlier stages of growth are illustrated by d, e, and f of figure 2. A full-grown larva is shown in profile within an open stem at figure 1, d, and the head and first two tho- racic segments appear in figure 2 at g. Mature larve measure about an inch (25 mm.) in length. In the District of Colum- bia full-grown larve, as already observed, occur as early as July 16; in New Jersey, later in July, and are to be found upon the vines in different stages in October; at Washington, as late as the second week of November. Fic. 2.—Squash-vine borer: a, Egg as seen from above; b, After attaining maturity same from the side, showing sculpture; c, sculpture of egg the larvee desert the stems greatly enlarged; d, newly hatched larva; e, half-grown larva; f, head of same from side; g, head of mature larva and enter the earth, bury- from above. a, b, and ¢, Much enlarged; d, ¢e,f,and g, less ing themselves to the depth enlarged. (Author’s illustration.) : of 1 or 2 inches, and form their cocoons, in which they transform to pupx. The cocoon (fig. 1,f) is constructed of silk and coated externally with fine particles of earth, which adhere on account of some gummy secretion of the larva. THE PUPA. The pupa, or chrysalis (shown in profile at e, fig. 1), measures about inch (16mm.) inlength. Itisshiningmahogany brown in color, and its head is ornamented in front just above and between the eyes with a hornlike process. By means of this the pupa cuts its way out of one end of its cocoon and by the aid of the abdominal hook- like spines forces itself to the surface of the earth before transform- ing to adult. NUMBER OF GENERATIONS. The question of the number of generations produced annually in localities of different temperatures which this insect inhabits has been solved by actual observation, the results serving to indicate that it is practically single-brooded on Long Island and northward; that there is a tendency to two broods in New Jersey, the moths in te THE SQUASH-VINE BORER, 5 exceptional cases completing their transformations late in August or September; that in the latitude of the District of Columbia the species is partially double-brooded, a larger portion of the moths, we may assume, developing as a second generation here than in New Jersey; and that in the Gulf States this species is undoubtedly fully two-brooded. PREVENTIVE AND REMEDIAL MEASURES. This borer is an exceptionally difficult insect to control, as ordinary insecticides are of no value after the msect has once entered the vines, and repellents are also practically useless. We are, therefore, depend- ent upon cultural methods for relief. Knowing that the insect passes the winter in the fields which it has ravaged, it should be superfluous to caution growers against planting squashes in the same ground in successive years. EARLY SQUASHES AS TRAPS. Good results have been obtained by planting as a trap crop and as early as possible a few summer squashes, such as crooknecks and early cymlings, before and between rows of the main crop of late varieties. The summer squashes attract the insects in such num- bers as to leave a smaller number to deal with upon the late or main crop. As soon as the early crop is gathered, or earlier if the ground is needed for the main crop, the vines are promptly raked up and burned to destroy all eggs and larve which they may harbor, and the same treatment is followed after gathering the late varieties. This method, according to the late Dr. J. B. Smith, has proved prof- itable where used in New Jersey and should produce good results farther north. Southward, where two well-defined broods appear, it might not be so productive of good, but it should be given a thorough test. FALL HARROWING AND DEEP SPRING PLOWING. Experiments conducted by Mr. F. A. Sirrine, of the New York Agricultural Experiment Station at Geneva, N. Y., show that this species can be greatly reduced by lightly harrowing the surface of infested squash fields in the fall so as to bring the cocoons of the vine borer to the surface, where they will be exposed to the elements, and then plowing in the spring to a uniform depth of at least 6 inches, so that the adults will not be able to issue. : OTHER CULTURAL METHODS. When the vines have attained some length parts of them should be covered over with earth, so that secondary roots will be sent out to support the plants in case the main root is injured by the borer. Keeping the plants in good condition, free from other insects and from disease, and well nourished with the assistance of manure or 6 FARMERS’ BULLETIN 668. other fertilizer if necessary, will also aid the plants to withstand borer attack. When vines are so badly infested as to be incapable of bearing fruit they usually die at once, and they should. then be promptly taken out and burned. The old vines should also be destroyed as soon as the crop is made. CUTTING OUT THE BORERS. The old-time remedy of cutting the borers out of the vines, although laborious, is useful, and about the only method open for employment after they have entered the vines. As several individuals often infest a single vine, it is best to cut longitudinally, so as not to sever the vine from the root stalk. If the wound made by cutting be afterwards covered with moist soil it will assist it to heal. The location of the borer in the vine can be readily detected by the accumulation of its yellow ‘‘frass’’ or excrement at the point where it is working, and which is kept open for the extrusion of this matter. CAPTURING THE MOTHS. This species may be held in partial subjection by keeping a sharp lookout for the parent moths, which are readily seen and not diffi- cult of capture toward dusk or in the cool of the morning, when they are comparatively inactive. The female may then be easily caught, just as she alights on a vine for oviposition. Several persons, includ- ing the writer, can vouch for this statement. SUMMARY. If the grower would make certain of securing a good crop in locali- ties where this and other enemies of the squash occur in their most destructive abundance, it will be necessary for protection against this borer to observe most of the following precautions, and, if pos- sible, secure the cooperation of his neighbors in their observance: (1) Not to plant in or near infested ground. (2) To plant early varieties for the protection of late squashes. (3) To harrow infested fields lightly in fall and plow deeply in spring, to prevent the moths from issuing. (4) To encourage the growth of secondary roots by covering the stems with earth. (5) To destroy dead vines and old plants as soon as the crop is made. (6) To keep the plants in vigorous condition, free from other insects and disease. (7) To cut out such borers as may succeed in entering the vines in spite of the employment of other remedial measures. (8) The capture of the moths before egg deposition is advisable. WASHINGTON : GOVERNMENT PRINTING OFFICE ; 1915 ta * 4 >) a a a je WA P VY AAR ; = Fy r UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS’ BULLETIN Bo Ad NES WasuinaTon, D. C. 671 May 26,1915 Contribution from the Bureau of Entomology, L. O. Howard, Chief. — HARVEST MITES, OR “CHIGGERS.” By F. H. CurrrenDen, In Charge of Truck Crop and Stored Product Insect Investigations. INTRODUCTION. Residents of the South and of the more southern portions of many of the Central States, and especially visitors to these sections, are often subject to great annoyance due to the attacks of mimute creatures popularly known as “chiggers” + and ‘‘red bugs,’’ and incorrectly as ticks. These creatures occur in black- berry bushes, shrubbery, grass, and weeds, and persons walking or sitting down in such localities are liable to attack. ‘‘Chiggers’” usually enter the skin near the shoe tops or at points below the knees, but some- times they are jarred from bushes or small trees on to the neck and other exposed portions. Their habit of burrowing under the skin is not nor- mal and brings about their death. fi ; Fig. 1.— Trombidium: sp.: Larva, highly Nevertheless the inflammation thus magnified. (From Banks.) caused may become very painful, and where many of the creatures have attacked a person this may fre- quently lead to fever or other disagreeable consequences. The desire to scratch the affected spots is very strong, and scratching with the fingernails may easily abrade the skin and might communicate infec- 1 The name “chigger”’ or “‘jigger’’ is evidently a corruption of chigoe, the pernicious sand flea (Sarco- psylla penetrans L.) of tropical America, a true flea, which crawls under the toe nails of man, producing painful sores which may result seriously if neglected. Note.—This bulletin, which is a reprint, with revision, of Circular No. 77 of the Bureau of Entomology, U.S. Department of Agriculture, treats of the harvest mite and means for the protection and relief of human beings subject to its attack, together-with methods of eradication. It will be of interest wherever this pest is troublesome. 90570°—Bull. 671—15 9 FARMERS’ BULLETIN 671. tion from the nails or other outside sources. . Children, and especially those who begin to go barefoot in grassy places in June to September, are great sufferers from this minute enemy. WHAT “CHIGGERS” ARE. These pests are the laryal or six-legged forms of harvest mites of the genus Trombidium, the adults of which have eight legs. For present purposes we may consider the harvest mites as a class. In figures 1 and 2 illustrations of some common forms are furnished. The larval harvest mites are of microscopic size, blood red, and shaped somewhat like a common tick, being nearly as broad in front as be- hind. They belong to the order Acarina and are not true insects (Hex- apoda), but are members of a distinct class (Arachnida) along with ticks, spiders, and the like. The parent mites are predaceous on true insects. As early as 1834 Mr. A. L. Dugés! made observations on these mites, which, as previously stated, have six legs in the immature or para- sitic stage, while the Fia. 2—Leptus americanus at left; Lepius irritans at right. Highly adultshave eight. The magnified, dots under anal extremity indicating natural size. adults are of different (After Riley.) shades of red and are quite visible. Many persons are familiar with the appearance of the young of certain species, as they occur on the under surface of the bodies of grasshoppers and harvest spiders or ‘‘daddy-long- legs” (Phalangiide) and under the wings of the house fly. Just what species of harvest mites are troublesome to man in the United States is not known, but one of them, perhaps the commonest, is referred to in literature as ‘‘Leptus” irritans Riley.” SYMPTOMS AND MANNER OF ATTACK. Soon after the harvest mite burrows under the human skin a small red spot appears (evidently the mite itself gorged with human blood), 1 Dugés, Ant. Recherches sur l’ordre des Acariens en general et la famille des Trombidiés en particulier. In Ann. Sci. Nat. Zool., t. 1, ser. 2, art. 1, p. 36, 1834; see also Megnin, P., Memoire sur les Metamorposes des Acariens en general et en particulier sur celles des Trombidions. L.c., t. 4, sér. 6, art. 5, p. 1-20. 1876; and Murray, Andrew, Economic Entomology, Aptera, p. 129-133, London, 1877. 2 Riley, C. VY. Poisonous insects, p. 745, fig. 2980, New York. 1887. (Extracted from Reference Hand- book of the Medical Sciences, v. 5.) Leptus is a genus founded on the larval Trombidium. Those who may desire further information in regard to the structure of theaadult may consult Banks, Nathan: ‘A treatise on the Acarina, or mites.’? (In Proc. U. S. Nat. Mus., v. 28, p. 30, 31, 1904.) HARVEST MITES, OR ‘‘CHIGGERS.’’ 3 after which the surrounding surface becomes congested, the affected area spreading until it is from less than a fourth to a half or three- fourths of an inch in diameter. This congestion may manifest itself within less than an hour after exposure or may not be apparent for 12 hours or so, the fever being at its height usually on the second day. The symptoms are apt to be first noticed when the sufferer has removed his clothing at night, or upon awakening from sleep. It sometimes happens that there is little irritation until some time after exposure, but with most persons susceptible to the poisonous effects of these mites irritation is first experienced on the second day. The feverish appearance of the afflicted skin area varies according to the susceptibility of the person attacked. Children dwelling or sojourn- ing in mite-infested localities suffer greatly from these pests, ex- periencing more severe annoyance than adults, and young women as a rule suffer more than older persons. People with thin, delicate skin and florid complexion are most afflicted by the mites, and with them the congested red spots are propor- tionately larger and more inflamed and irritating. Many persons, however, as, for example, permanent residents of infested regions, and particularly farm laborers, seem to be practically proof against the toxic effects of harvest mites and go with impunity into places overrun with them. This im- munity to poisoning is obviously due to two causes: (1) To outdoor work which toughens the person’s skin, especially such portions of the arms and legs as are much exposed to the sun and weather; and (2) to inoculations, due to frequent infection. The inflamed spots due to the presence of the mites under the human cuticle are often diagnosed as hives, nettle rash, urticaria, or the “wheals,” and resemble closely those produced on many persons by the “bites” of fleas and some mosquitoes, but on the second or third day each of the mite-infested areas is usually found surmounted at the middle by a minute vesicle or water blister. This is obviously the most important characteristic of harvest-mite attack. After the subsiding of the inflammation and itching, which takes place in a few days, a small scale or scab frequently forms, leaving on some persons a scar which does not wholly disappear in extreme cases for weeks. The mites naturally attack first those portions of the body which are most exposed—those nearest the ground. They crawl into the -" Fic. 3.—Trombidium sp.: Adult, high- ly magnified. (From Banks.) 4 FARMERS’ BULLETIN 671. stockings and penetrate the skin about the ankles, frequently below the shoe tops, and are usually found most numerous below the knee. According to;the late Dr. John Hamilton, a physician as well as entomologist, the harvest mites enter the larger sweat tubes or pores of the skin, and as these tubes are very tortuous, the progress of the mites is necessarily slow, from 18 to 36 hours being required for. them to reach the end. When the lesions caused by these mites are unusually numerous, the sufferer becomes feverish, and sleep is much disturbed. Sometimes the afflicted one becomes frantic and lacer- ates his flesh by too vigorous and frequent scratching. Erysipelas is known to follow severe attacks, and death resulting from blood poi- soning is recorded. These more serious results of infestation are, however, exceptional and, as with the fatalities which in rare cases follow the ordinarily merely painful or annoying ‘‘bites”’ of many insects, undoubtedly point to an impurity of the blood. HABITAT. Harvest mites are most abundant in damp locations, along the borders of streams and other bodies of water, and on the edges of forest and woodland. They occur also on trees and shrubbery, evi- dently infesting the lower surface of the leaves, from which they drop off when these are rudely shaken, and find lodgment on the neck or other exposed parts of the body. Riley describes ‘‘ Leptus ameri- canus”’ as affecting chiefly the scalp and armpits. In places infested by harvest mites it is a matter of danger to sit down or li in the grass and herbage for any length of time, as the mites will then have easy access to almost any portion of the body. As a rule these creatures appear to be dependent on the shade and not to live in the direct sun- light, but some forms occur in sunny locations. These mites are most abundant and troublesome in the Tecioiea and become less numerous as we go northward. They are generally distributed in the Gulf States, up the Mississippi River to Missouri and Illinois, and through the Atlantic Coast States to northern New Jer- sey. They appear to be unknown in New York and New England, or north of latitude 40° in the East. Trouble from chiggers has also been reported in portions of Ten- nessee and practically throughout the State of Ohio, because we have record of injury as far north as Sandusky, which is on Lake Erie, Lima, in the northern part of the State, Cincinnati, and Columbus. Reports that these creatures have also been found in other localities may and may not be true at the same time, since with the cultiva- tion of the soil and the destruction of-wild bushes and other places of harbor they have practically disappeared. There are reports also of the occurrence of chiggers at Horicon, Wis., and La Fayette, Ind., in Minnesota, and at Belvidere, S. Dak. HARVEST MITES, OR ‘‘CHIGGERS.’’ 5 Several reports have been received of a plague of these mites in the vicinity of Chicago, Ill., showing similar distribution in that State. Chiggers are well distributed in Kansas, and reports would indicate similar conditions in Indiana and portions of Iowa. Harvest mites are well known in England and Scotland under this name and as ‘‘gooseberry bugs.” On the Continent of Europe, also, they are abundant, especially in Belgium and the Netherlands, in parts of Germany, and in France. Indeed, in some of these countries they have at times caused considerable annoyance to the peasantry, whom they have hindered or prevented in the harvesting of certain crops. The mites are troublesome, too, in tropical America, in the West Indies, and in Japan. LIFE HISTORY. The life history of a harvest mite, as related by Mr. Nathan Banks, is substantially as follows: The female lays her eggs in or upon the ground, sometimes to the number of 400 in one place. The eggs are usually brown and spherical and have been considered by some early writers as fungi. The chorion or outer skin splits soon after the eggs are deposited, dividing the eggs into halves and exposing the pale vitellne membrane. The larva when hatched is circular or ovoid in outline, and each of its three pairs of legs is tipped with two or three prominent claws. After the larva has become attached to its insect host it elongates and becomes swollen with food. When full fed it drops off, seeks a convenient shelter, and gradually changes in shape without molting. The new parts are formed under the larval skin, which after a few weeks cracks and discloses the adult Trombidium. The mature harvest mite is predaceous, wandering about and feeding on aphides, small caterpillars, and, in the case of one species, on the eges of grasshoppers or locusts. It hibernates in the soil or in other sheltered locations and in the spring deposits its eggs. There appears to be asingle generation produced each year. Only a few forms have been reared. The larva of one occurs commonly on the house fly in autumn. REMEDIES. As harvest-mite infestation is usually contracted by walking or working among blackberry and other shrubbery which harbors them, or by walking, sitting, or lying among grasses or similar herbage along streams or pools, on the edges of marshes, or under trees near such places, it is obvious that the best means of prevention is the avoidance of exposure by susceptible persons. If, however, a bath is taken in hot water, or water containing salt or strong soap, within a few hours after exposure, no ill effects will be experienced. After a longer exposure a bath has practically no effect, and direct remedies are necessary. 6 FARMERS’ BULLETIN 671. Sulphur is a sovereign remedy for mites and is the best preventive of attack. When exposure is unavoidable and where vegetation is not more than 2 or 3 feet high, a sure preventive is found in sifting flowers of sulphur into the underclothes from a little above the knee downward and,into the shoes and stockings, or it may be rubbed over legs and ankles. Naphthalene has been successfully used in the same manner... While the sulphur, being inodorous and perfectly effective, is undoubtedly preferable against harvest mites alone, naphthalene is a safeguard against various forms of man-infesting tropical insect pests. Vaseline, pure or mixed with sulphur, will serve the same purpose, but is not so agreeable on account of its oily nature and the certainty of its soiling the clothing. For most localities these precautions are to be observed through the months of July, August, and a part of September. The mites are seldom bothersome in early June or as late as October, but in exceptionally warm seasons they are apt to be encountered in both months. If exposure has been unwittingly incurred or precautions have been neglected and the characteristic irritation has set in, warning the patient of, trouble to come, a counter-irritant or cooling lotion should be applied directly to the affected parts. For this purpose moderately strong ammonia, applied when the symptoms are first manifest, has offered the best results, and the writer recommends it above all other direct remedies. Bicarbonate of soda, or common cooking soda or saleratus, may be substituted in supersaturated solution. Similar alkaline solutions would probably also serve in counteracting the insect poison, which is acid. These substances should be applied liberally until the irritation subsides. Some per- sons have testified to the value of a 10 per cent dilution of carbolic acid. Alcohol, camphor, essence of peppermint, and similar prep- arations are very ‘‘cooling,”’ but afford, as a rule, only temporary relief. A dilute tincture of iodine or collodion applied lightly to the affected parts is a good remedy in case of severe suffering. The latter acts by protecting the ‘‘sore’’ spots from the air. DESTRUCTION OF THE MITES IN THE FIELD. Much complaint has been made of the presence of harvest mites on lawns and in vegetation in country grounds and along pathways and roadsides, and information has been solicited by many, including officers of country clubs and the like, for methods of eliminating the mites from such locations. This can be accomplished by keeping the grass, weeds, and useless herbage mowed as closely as feasible, so as to expose the mites to the sun. In some cases this can be facilitated by dusting the grass and other plants, after cutting, with flowers of sulphur or by spraying with dilute kerosene emulsion in HARVEST MITES, OR ‘‘CHIGGERS.”’ 7 which sulphur has been mixed. Grasses on the borders of ponds frequented by cattle, wild blackberry bushes, and similar plants should also be cut down and destroyed in the vicinity of houses and - where children and older persons are liable to mite infestation’ by passing through them. Well-cultivated fields kept free from weeds are not infested with ‘‘chiggers,’’ and in the course of' time, perhaps a year or two, the measures prescribed, if carefully carried out in grassy locations, should also entirely free these from the pests. In severely chigger-infested tracts of, say, 400 acres, where there are no bushes or shrubs of value, cattle may be inadequate, and correspondents and others have stated as their experience that after turning sheep into the fields the chiggers were destroyed. Undoubt- edly this was due largely to the fact that the sheep kept the grass more closely cropped than cattle would have done, but there is also a belief that the chiggers ascend the legs of the sheep and that the oil or lanoline of the wool is responsible for their death. Hence it is believed that sheep turned into large tracts such as deseribed would accomplish the eradication of the mites more thoroughly and in a shorter space of time than would perhaps any other domestic animal, even including goats, which might be used in some Cases. For the eradication of chiggers on the grounds of wealthy private individuals and clubs the application of ordinary flowers of sulphur might be both cheaply and thoroughly made by the use of one of the dust blowers used for dusting potatoes with Paris green, or by one of the sulphur dusters used for spraying orange trees for the red spider in California. These sprayers are capable of throwing a fan-shaped dis- charge about 8 feet wide and effect very even and thorough distribution. The cost of application, allowing 50 pounds of sulphur per acre, should be from $1 to $1.50 per acre, and since with one man and a team 30 to 40 acres a day may be covered, the expense of application is not great. Such a duster costs from $65 to $80. WASHINGTON ; GOVERNMENT PRINTING OFFICE; 1915 IV. INSECTS." UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS’ BULLETIN Wasuincton, D.C. 674 Jury 8, 1915. Contribution from the Bureau of Entomology, L. O. Howard, Chief. CONTROL OF THE CITRUS THRIPS IN CALIFORNIA AND ARIZONA. By J. R. Horton, Scientific Assistant, Tropical and Subtropical Fruit Insect Investi- gations. INTRODUCTION. The citrus thrips,’ a minute orange-yellow insect, has in the past few years caused extensive damage to citrus fruits in the San Joaquin Valley of California and also occasioned considerable injury in southern California and Arizona orange groves. The nature and extent of the injury caused by this insect and its life history and habits were carefully studied, and extensive experi- ments for its control were conducted by the writer during the period from 1910 to 1912. It is the purpose of the present paper to give briefly the practical control measures resulting from these studies. INJURY. The citrus thrips is a sucking insect feeding on the plant juices of the leaves, the fruit rind, and the bark of tender stems, in much the same manner as the mosquito draws its food from its victims. For this reason the insect can not be killed by stomach poisons sprayed on the plant, but must be controlled by sprays that kill by contact. The injury caused by the citrus thrips begins with the seedling orange tree. The leaves are scarred and distorted, and to a certain extent the stock is devitalized. When the seed stock is budded and the foliage of the seedling trimmed off, the thrips attacks the bud. Nursery buds will make a fine, luxuriant growth of 2 or 3 feet in a 1( Euthrips) Scirtothrips citri Moulton; order Thysanoptera, family Thripide. Notre.—This bulletin is of interest to the citrus growers of the Pacific coast and the Southwest. 92706°—Bull. 674—15 9 FARMERS’ BULLETIN 674. season if properly sprayed to protect them from thrips. On the other hand, many nursery trees have the leaves and stems so badly scarred and twisted as to give them a blighted, unsightly appearance, and are so retarded in growth that they must be held in the nursery for a year or more beyond the proper time for sale in order to meet the size requirements, thus decreasing the nurseryman’s profit by the cost of the extra care. It sometimes happens that this class of stock is sold along with better trees, and the thrips injury continues for Fic. 1.—Injury to young oranges by the citrus thrips (Scirtothrips citri). (Original.) several years in the orchard. The writer knows of 5-year-old and 7-year-old groves in the foothills of Tulare County which have been held back, principally by thrips, to such an extent that the trees are no larger than 3 and 5 year trees in less infested situations. From the general appearance of such trees it seems evident that they will never attain the size and bearing capacity of trees which have escaped severe thrips infestation in the nursery and during their early years in the orchard, CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. 3 As the young fruit appears it in turn is attacked (fig. 1), and its market value at maturity is much reduced by the enlarged feeding scars and scabbing (fig. 2). A larger percentage of small-sized fruits than ordinarily develop results, and there is a total loss, as the result of early and severe scabbing, of a proportion of the fruit. To calculate the damage caused by the insect in reducing the grade of the fruit, it is necessary to know the system of grading and the relative market value of the grades. Three packs are usually made in California packing houses at the time of this writing, these packs or grades being variously designated as ‘‘Fancy,”’ ‘‘Choice,”’ and ‘‘Standard”’; ‘‘Extra Fancy,” Fic. 2.—Mature oranges, showing injury by citrus thrips. (Original.) ‘‘Fancy,” and ‘‘Choice”’; or ‘‘Extra Choice,” ‘‘Choice,”’ and ‘‘Stand- ard.’’ Whatever the terms used there is usually little difference ir the quality of fruit of corresponding grades at the different packing houses. In other cases only two divisions are made, the first grade generally being designated as ‘‘Orchard Run” and the second or lower grade as ‘‘Standard.’’ Under the latter system the quality of the fruit composing the first grade is about the same as would be obtained by placing together all the fruit of the first and second grades of the three-grade pack. Statistics upon the quantity of fruit shipped from the entire San Joaquin Valley and the prices received for it are not available, but from Lindsay and its tributaries 1,525 carloads of navel 4 FARMERS’ BULLETIN 674. oranges were shipped in 1911. The approximate average number of boxes of fruit to the car is 390, making 594,750 boxes for the season’s shipment. From examination of thousands of oranges in the field, throughout the district and in many groves, it was calculated that 34 per cent of all the fruit would be classed as first grade so far as thrips injury was concerned, 43 per cent as second grade, and 23 per cent as third grade. Returns received by different packing houses on a total of 358,000 boxes of navels of all grades for the season in- dicated the following average differences in price per box between the different grades. First-grade fruit averaged 37 cents more per box than that of second grade; the latter 28 cents more than that of third. Fruit shipped in only two grades gave an average difference of 51 cents per box in favor of the first grade. _It may be seen from the foregoing data that 43 per cent, or 255,742 boxes, of the Lindsay fruit was re- duced to second grade at a loss of 37 cents per box, or $94,624.54; 23 per cent was reduced to third grade at a loss of 65 cents per box, or an additional $88,914.80. There was thus a total loss for the Lindsay district alone of approximately $183,539.34 in the season of 1911 from grade reduction caused by thrips. SUMMARY OF SEASONAL HISTORY. In seasons such as 1911, adult citrus thrips first appear in April and — increase rapidly during April and May, during which time the insects are congregated largely on the fruit and foliage of the orange. During part of June, July, and August the adults leave the toughening fruit and leaves of the orange and disperse over miscellaneous food plants, and it is during this period of wider separation that mating and oviposition are somewhat checked. In August and September there is a series of flights back to the late summer growths of the orange, where the insects concentrate in large numbers, mating and actively depositing the eggs which produce the insects of the following spring. The citrus thrips begins to disappear about the middle of October, and after December practically none can befound. There are generally afew larvee and adults in places on the trees until the early part of Jan- uary, at which time they disappear completely. The eggs which are deposited in the stems and leaves of the orange in the fall mostly pass the winter successfully, hatching during the ensuing March, April, and May. The seasonal activities of the citrus thrips, as related to orange blossoming, growth periods, and spraying are summarized graphically in figure 3. SUMMARY OF LIFE HISTORY. There is a tendency on the part of the citrus thrips to breed through- out the year. All stages of the insect are found on the trees through- out November and December. Larve, pup, and adults gradually CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. 5 die off as the weather grows colder, until by the middle of January all have disappeared. The winter is passed only in the egg stage. Eggs deposited in the leaves and stems, mostly during late August, Septem- ber, and October, hatch and the larve appear in March, April, and May. The average duration of the egg stage of summer generations varies from 10 to 18.8 days during Mo and June, 6.8 to 8.5 days in July and August, and 17 to 18.8 days in September and October. The average larval stage varies from 6.6 to 13.7 days during April and May, 4.2 to 9 days from June to August, and 6.7 to 11.2 days in September and October. The average pupal stage varies from 4.7 to 13 days during April and May, 2.8 to 5.1 days from June to August, and 5 to 19.9 days from September to November. Pupation takes place in crevices on the tree trunk, in dead leaves and rubbish under the trees, and under clods and particles of trash DUNE | JULY | AU6UST sas =a Tt ' = Ea eee, GE FOLIAGE a Se =a a ae SIISCELLANEOUS : a ae ial << overwinter eces | £665 ae Fic. 3.—Graphic illustration of the seasonal activities of the citrus thrips as related to blossoming and later growth periods of the orange, and indicating also the spray periods. (Original.) - aaa a “Shen 5 ae on the ground, but never in the ground. The pupa is naked, does not construct a cell, and is at all times capable of locomotion. The average duration of adult life is from 25 to 35 days, with extreme instances running to from 46 to 49 days. Adults can live from 2 to 6 days only without food. The number of generations in a season will depend upon the char- acter of the season. An early, warm spring followed by a prolonged, hot summer may result in the production of eight or more genera- tions. In seasons such as 1911, six full generations may be expected between the middle of April and the first of November. For pur- poses of control the citrus thrips must be treated as an insect having only a single generation a season, and with an egg-laying pera extending from April to November. 6 FARMERS” BULLETIN 674. REMEDIES FOR THE CITRUS THRIPS. Certain measures against the citrus thrips have been persistently recommended in spite of abundant evidence of their inapplicability. These are usually directed against the pupal stage and consist in the. application of insecticides to the soil, breaking the soil up fine to destroy the insects supposedly pupating there, and burning dead leaves and trash, which accumulate under the trees, to destroy the pup. These methods are worthless for the reason that the thrips Fic. 4.—Resin-wash injury to half-grown oranges sprayed for the citrus thrips. (Original.) do not go into the soil at all, and only a varying and often small percentage of them pupate in the trash. Fumigation with hydro- cyanic-acid gas will reach and kill only the larve and a small number of adults, and is accordingly too expensive to use. Dis- tillate-oil emulsions and proprietary emulsions containing distillate, even when used as weak as 2 per cent, stain the ripe oranges, and are otherwise so injurious that it is considered unsafe to use them. Commercial lime-sulphur is not noticeably injurious when used at less than 1 part to 28 parts of water. . Resin wash can not be safely used on orange trees at any strength. Where the resin mixture comes into contact with the fruit the epidermal cells are killed and CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. i a shallow brown scab is formed. (Fig. 4.) Where the liquid col- lects in large drops it forms a thick, amber-to-black scab which does not slough off readily. About 20 per cent of the fruit at picking time was thrown into the lowest grade owing to scabbing through the use of the weakest resin wash. There is only one cheap and effective method of citrus-thrips control, viz, the application at high pressure of contact insecticides, preferably mixtures containing sulphur in solution. Sulphur mix- tures at the proper strength have given uniformly high killing results and have thus left no doubt as to their insecticidal power over this species. They further show a more or less marked tendency to repel the insects and prevent rapid reinfestation of sprayed trees. SPRAY MIXTURES AND DILUTIONS. Of the large number of combinations of insecticides tested, the following have given the best results, and any of the mixtures here recommended may be.relied upon to do good work: 1. Commercial lime-sulphur.—li the lime-sulphur is of a density of 36 degrees on the Baumé scale, dilute 1 gallon with 56 gallons of water; if of a density of 33 degrees Baumé, dilute 1 gallon with 50 gallons of water. 2. Sulphur-soda solution.—Two gallons of the stock solution, prepared as described on page 8, diluted with 25 gallons of water. 3. Commercial lime-sulphur and blackleaf tobacco extract (40 per cent nicotine sul- phate).—Dilute 1 part of the commercial lime-sulphur, if 34 to 36 degrees Baumé, with 86 parts of water; if 30 to 33 degrees Baumé, with 75 parts of water. Then add 1 part of the tobacco extract to 1,000 parts of the lime-sulphur diluted as above. 4. Blackleaf tobacco extract (40 per cent nicotine sulphate).—Dilute 1 part with 800 parts of water. COMMERCIAL LIME-SULPHUR. The commercial lime-sulphur, diluted with water and without the addition of other chemicals, is preferred to any of the other insecti- cides because of its cheapness and convenience in mixing. Very good grades of lime-sulphur can be purchased in the market at a reasonable price, and since the preparation of this product requires care and experience, and as it must be made fresh each time or special precautions taken to store it in air-tight containers, its home manutacture is not advised. When necessary to carry the market product over a season it is essential to protect it absolutely from the air, asit rapidly loses its insecticidal power when exposed through leaky barrels or an open bung. SULPHUR-SODA SOLUTION. Another mixture contaiming sulphur as the most important ingre- dient is made by dissolving sulphur with the aid of caustic soda, according to the directions given below. This mixture, though 8 FARMERS’ BULLETIN 674. practically as effective in controlling the citrus thrips as lime-sulphur, can, not be purchased ready-made and is therefore less convenient to handle. Furthermore, at the present writing it costs Just as much per dilute gallon as the factory-made lime-sulphur. The sulphur-soda stock solution is prepared as follows: Powdered ‘sulphiur-emee-. ------- -- ager ae - te 30 pounds. Powdered caustic soda(98 per cent) epee... 2 bl. 15 pounds. Waterttolimalke sae eeere 2... es eee 30 gallons. The sulphur is made into a paste with water, and while the mix- ture is being constantly stirred the soda is added in sufficient quantity to start boiling. As boiling becomes violent a litile water is added co retard it. When the sulphur has all been taken mto solution enough water should be added to bring the stock solution up to 30 gal- lons. If made according to the foregoing directions the final product will be a clear, amber-colored liquid much resembling good commer- cial lime-sulphur. PLAIN TOBACCO EXTRACTS. Tests with plain tobacco extracts without the addition of lime- sulphur or other preparations have given very good results when the tobacco has been used at sufficient strength. Tobacco extract con- taining 40 per cent nicotine used at the rate of 1 part-to 800 parts, liquid measure, of water is quite satisfactory ; when diluted at the rate of 1 part to 1,600 parts water, however, its efficiency is noticeably lowered. It can not be recommended for this work in solution weaker than 1 to 1,000, and should preferably be used at the rate of 1 to 800. The commercial tobacco extract contaming a high percentage of nico- tine sulphate is very convenient to handle and costs approximately $0.016 for each gallon of the diluted spray, when used at the rate of 1 part to 800 parts of water. TIME AND NUMBER OF SPRAY APPLICATIONS. Unfortunately no specific dates, which will hold for every season, can be fixed for the applications of the spray. The investigations of the seasons of 1910 and 1911 have shown that the date on which the thrips first become numerous and injurious and the navel-orange blossoms lose their petals varies as much as 30 days in certai seasons, due to the nature of the spring weather, and, further, that it varies in different orchards in the same season. The greatest injury to the fruit is done between the time the petals fall and the fruit is half grown. It has been demonstrated that three applications of the insecticide are necessary during this period to prevent marking of the fruit. The first spring growth has usually hardened by the time CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. 9 the petals have all fallen, and the thrips then seek the young fruit. The petals do not all fall at once, but come down gradually, and the transfer of thrips is therefore gradual. The first application should be made as soon as four-fifths or more of the petals have fallen. This checks the imsect at a time when the orange is most susceptible of deep injury and when the blossoms have passed the period at which pollmation might be mterfered with by the spray. After the first application more larvee will issue from eggs deposited in the very young fruit, and additional adults will appear from the specimens pupating at the time of the application. The second application must therefore be timed to prevent this renewed attack, which may be expected to reach the danger pot in from 10 to 14 days after the first spraying. ‘This second spraying should not be too long delayed, as a comparatively few larve may, by their persist- ent habit of feeding in a circle about the base of the fruit, cause con- siderable injury. Special effort should be made to drench all the fruit as well as the few remaining tender leaves thoroughly, as it is here only that the msects occur. The third application may be longer delayed if the first two have been thorough and. well timed. It generally takes the insects from two to three or four weeks to become dangerously numerous again, as they reinfest the sprayed trees very much more slowly after the second application. After the third application the fruit rapidly loses its attractiveness, and the insects then find it necessary, in order to secure food, to spread out over the few remaining tender orange leaves and certain miscellaneous food plants. Durmg the latter part of August and in early September there is usually another abundant growth of shoots upon which the thrips congregate 1 great numbers. A fourth appli- cation in late August or more probably in September should be timed to catch the insects as soon as they become numerous and before any ereat amount of leaf injury appears. The importance of protecting this growth is evident to those familiar with the stunted condition of orange trees in certain orchards of Tulare County as the result of continuous feeding of large numbers of thrips during the first five or six years of growth. The writer has in mind an orchard in which trees five years from the nursery are no larger than the average 2-year-old trees in localities more favor- ably situated with regard to thrips, and which each year have a very large percentage of the leaves so severely injured that they roll up into tight curls. 10 FARMERS’ BULLETIN 674. SPRAY APPLICATIONS TO NURSERY STOCK. While definite dates can not be given for the application of sprays to nursery stock, it follows in the case of trees budded in the fall, where the original stock is allowed to put forth a good growth in the spring, that it is sometimes advisable to spray during April, but only when thrips have become quite numerous and for the purpose of ridding the trees of them before the scion has grown sufficiently to attract them. Preferably the stock should be largely cut back as soon as the bud is well under way, and this is generally done in Tulare County before May 1. The prun- ings should be burned in every case to destroy eggs and larve which may be present. The growing scions must then be watched carefully, and as soon as thrips appear in numbers spraying should begin. They should be further watched with the same care throughout the remainder of the growing season and sprayed as often as the abundance of thrips makes them liable to severe injury. Nursery stock will usually require from three to five applications a season, depending largely on the amount of growth it produces. Once the scion has completed its first growth and become distasteful to thrips the next most important growth will usually occur late in July or in August. Fig. 5.—Correct spray rod and nozzle connec- To summarize, the first applica- tions: a, Two nozzles fitted on “Y” branch; tj9n should be made when thrips b, shut-off at base of spray rod. (Original.) ; r begin to get numerous on the spring growth, usually between April 15 and May 15, after which from two to four further applications will be necessary, according to the con- ditions of infestation. - SUGGESTIONS ABOUT SPRAYING. The gasoline-power outfit, by reason of its large nozzle capacity, simplicity, reliability, and comparatively low cost of operation, is the only class of sprayer here recommended for spraying bearing orchards, young orchards in excess of 10 acres, and large nurseries. Hand- power outfits, when of the right type and capable of maintaining a pressure of not less than 125 pounds, are suitable and even preferable CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. 11 for spraying seed-bed and nursery stock, and they may also be used in young orchards of small acreage. The spraying outfit should be on hand, set up, and in perfect running condition not later than April 1, and the insecticide materials at hand and conveniently located near the water supply, and as close as possible to the orchard or nursery to be sprayed. It is neces- sary to order supplies not later than the January or February pre- ceding the spraying operations in order to insure having the material at hand when wanted. HOW TO SPRAY BEARING ORCHARDS. It is best to use only two 50-foot leads of hose on a power outfit, with 10-foot rods each fitted witha‘ Y”’ (fig. 5) which is angled to handle two nozzles. The latter should be of the large chamber type, with disks bored to one-sixteenth inch, and should throw a double cone of spray which breaks into a fine mist at about 4 feet (fig. 6). The first application should usually be started just be- fore all the petals are down. While the sprayer is being driven between the rows each rodman should begin work at about the middle of his tree on the side away from the sprayer and work around the tree until he meets thestarting point; he should then switch to the same point on the next tree without shutting off the nozzles and with asmuch economy of movement as possible. (See figure 7, which shows easy and correct position for spraying.) The nozzles should be held about 2 feet from the tree so that the broad portion of the stream plays upon fruit and leaves. The trees should be swept from tip to base, special attention being given to the fruit and the tender growth, where the insects congregate. The pressure, if maintained at 150 pounds or more, will turn the leaves over so that both sides will be sprayed. No Pia. 6.—Mist spray from twin nozzles. (Original.) Le FARMERS’ BULLETIN 674. attention need be paid to the inner portions of the tree, as thrips do not oceur there. One should not attempt to spray too many trees with a single outfit, and an application once commenced should be finished within Fic. 7.—Correct position of operatorinspraying. (Original.) 10 days. It has been found after much experi- ence that only about 25 acres of from 12 to 18 year old trees or 50 acres of from 5 to 7 year old trees can be successfully handled with one gasoline- power sprayer. This is calculated on the basis of ten 200-gallon tanks of spray per day, allowing 8 gallons per tree for trees from 12 to 18 years old or 4 gallons for trees from 5 to 7 years old, allowing 100 trees to the acre. It is a common mistake to use the wash too spar- ingly and to try to get over the ground too fast. Table I, published: also in a former report,'4was pre- pared to show approxi- mately the correct amounts to apply to trees of dif- ferent ages, and from it the quantity of spray material required for the season may be estimated. TABLE I.—Quantities of liquid required in spraying for the citrus thrips. Age of aise Pues One application. Gallons | Gallons aati dilute | per acre eears. spray of 100 per tree. trees. 2 to 3..- 2 200 5to7...) 4 ~ 400 8to10-..} 5 500 12to 18.) 8 800 1Jones, P. R., and Horton, J. R. The Orange Thrips: A Report of Progress for the Years 1909 and 1910. U.S. Dept. Agr., Bur. Ent., Bul. 99, pt. 1, iv+16 p., 2 fig., 3 pl., Mar. 6, 1911. Seep. 15. CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. 13 The spraying must be very thorough, and to be effective the insects must actually be hit by the spray. It will very much improve the results if the rodmen are shown the insect they are to spray for and just where it will be found in greatest numbers. In this way the object of spraying is made definite. By keeping the thrips reduced to a minimum during the period between the dropping of the petals and the time when the fruit is half grown, most of the fruit scarring and the leaf curl of the early summer growths of foliage can be prevented. An appheation at the proper time in late August or in September will prevent the severe leaf curling which usually occurs to all late summer growths. HOW TO SPRAY NURSERIES AND YOUNG TREES. For large nurseries, where the gas-engine outfit can be advan- tageously used, it is preferable to the hand outfit. Two 25-foot or even 15-foot leads of hose and 12-foot spray rods are generally most convenient for this work. However, when an outfit has already been fitted with 50-foot hose and 10-foot rods, with the intention of spray- ing older trees as well as nursery stock, this equipment may be made to serve very well for the latter. In such case the excess hose length should be coiled over a peg or bracket fastened to the spray tank or engine hood, so that the young trees will not be injured by the drag- ging hose. It is preferable in setting out a nursery to leave driveways wide enough to accommodate a sprayer and team at intervals through- out the length of the bed. Where it is desired to have the nursery rows 4 feet apart, which is the usual practice, it is convenient to have wagon room between the fourth and fifth rows from one side, and again between the 12th and 13th, 20th and 21st, etc. With this arrangement eight rows of trees, four either side of the driveway, may be reached each trip, using 12-foot spray rods; eight more rows may be taken on the return trip, ete. The large chamber-type or single Bordeaux nozzles may be used to good advantage, but the rapidity of delivery of the spray need not be so great as that necessary for orchard work. It is better to pro- gress more slowly, covering all portions of the little trees, without undue waste of liquid. The trees will need attention only when the growth is tender. 14 FARMERS’ BULLETIN 674. COST OF SPRAYING AS COMPARED WITH RETURNS.! Thrips injury to citrus fruits is confined to the rind and does not appreciably affect the eating quality of the fruit. Except in seasons of unusually gross infestation no great amount of fruit is lost entirely by reason of thrips injury. The argument has been advanced that where the fruit is separated into but two commercial grades, which embrace everything fit to ship, as is now largely the case, thrips injury will have but little effect on the price. The damage thrips do to the trees by interfering with the functions of the leaves throughout the early years of growth, however, is generally overlooked. The following statement takes no account of this indirect injury to the trees, which is difficult to estimate, but merely gives the profit realized from producing a better grade of fruit by spraying. Cost of spraying one acre of 18-year-old navel orange trees. Labor: 2 rodmen at $2.50 each per day, cost per acre.............-......:-2.--- $1. 22 Driver and team at.$o per day, cost peracre.........2.2....5.2..2.0.0% 128 Gost.of labor per acre eno plicationee 02... och ask.com cote - ie ee 2.45 Insecticide: 14 gallons lime-sulphur at 14 cents, cost per acre, one application... ..... 1.96 Fuel, oil, and miscellaneous: Gasoline, 14 gallons at 25 cents, per acre, 3 applications.................. . 625 Oil at $1 per gallon, per acre, 3 applications...........:/....-.. Meee tte. 2 ne 8 ee ee $29. 58 Profit from sale of fruit. Amount saved per acre by spraying. .. -Suaeee. 6: 2.2 Sk: ioe ee $29. 58 Cost’ of spraying pebacres- 6... .. . ... eee oe ee eee | 14.09 Clear gain per acre fromthe. treatments geese eo - gue 2 41s se eee 15.49 1 The figures given upon cost of spraying are based on the Bureau of Entomology’s own spraying work in the season of 1911. The number of boxes of fruit given, 324 per acre, was the actual production of the portion of grove under experiment, and as these trees were not at their best and since 18-year-old trees usually produce more than 324 boxes per acre, the saving effected by spraying would tend to be greater in most cases. The difference of $0.51 per box between first and second grade fruit was that which was actually shown by packing-house returns, and practically all the grade reduction was caused by thrips alone, CONTROL OF CITRUS THRIPS IN CALIFORNIA AND ARIZONA. bb In the above calculation the cost of spraying an acre of 18-year-old trees is higher than will usually be the case, since, as a rule, the grower is obliged to have a team on hand all the time and may there- fore reduce the item of team hire; he may also be able to reduce the cost of labor somewhat in many cases. In seasons of gross infesta- tion, and in certain orchards every season, the returns will be greatly increased over the figures given because of the excessive infestation in such seasons and orchards. WASHINGTON ; GOVERNMENT PRINTING OFFICE ; 1915 FARMERS BULLETIN Wasuincton, D.C. 675 Juny 6,-1915. Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE ROUNDHEADED APPLE-TREE BORER.’ By Frep E. Brooks, Entomological Assistant, Deciduous Fruit Insect Investigations. INTRODUCTION. Several species of insects occur in the United States that in their larval or grub stage injure apple trees by boring into the bark and wood. The most destructive of these, in the eastern half of the coun- try, is the roundheaded apple-tree borer. The borers of this species hatch from eggs de- posited by a rather 2 large beetle in or ae under the bark of the trees, usually near to the ground, | ‘ and feed to such an extent on the inner bark and wood that S the trees are greatly ‘ weakened and often \ die as a direct result of the injury Trees Fic, 1.—Distribution of the roundheaded apple-tree borer ; (Saperda candida). (Original.) . ; SD NS \\\ rs NN ESS EMaevlanid! e3e gaa progress from the last of May until the middle of July, the period being somewhat later in the season than the dates given at the higher elevations of the mountain districts. THE LARVA. The larva, or borer (figs. 9, 10), is a whitish, footless grub, with brown head and black jaws. It attains a length when full grown of nearly an inch and a half. On hatching, the young borers attack the inner ‘bark, where they continue to feed until late in the season; whereupon some of them, especially in young trees with thin bark, THE ROUNDHEADED APPLE-TREE BORER. ff enaw their way into the sapwood. During the first season the young borers feed and grow rapidly, and where several occur in one tree they may completely girdle and kill it before winter. Their burrows at this time are in the form of broad, irregular, usu- ally more or less circular gal- leries beneath the outer bark, near to the point where the egg was laid. The borers aveid one another in the tree, and the forms of their galleries are often affected thereby, being made narrower and more elongate to avoid contact. This habit in- creases the liability of their : " Fie. 6.—Inner surface of bark peeled from being overlooked by orchard- young apple tree showing position of eggs - ists who practice the digging- of roundheaded apple-tree borer. Natural i Size. (Original.) out, or “worming,” method. As the borers feed they keep an open space in the burrows about themselves, thrusting their castings into abandoned corners or out through small holes made by them in the bark. These cast- ings form little heaps of reddish, stringy wood fragments around the base of the tree (fig. 11) and afford one of the sure marks by which infested trees may be detected. The borers spend their first winter in the burrows near the ground and _ re- sume feeding early the following spring, attack- ing now the solid wood almost exclusively, and, in young trees, penetrating to the heart. During the Fic. 7.—Female beetle splitting the bark of a young apple tree just below the surface of the ground preparatory to depositing an egg. (Origi- summer those that are to mal) attain the adult stage the following year Rent to extend their burrows up the trunk a half 8 FARMERS’ BULLETIN 675. inch or more beneath the bark. As previously stated, part of the borers do not become adult until they are 3 years old; these re- main feeding in the wood near the ground until the third summer, when they, too, work their way up the trunk in the manner just de- scribed. The winter previous to pupation is passed by the borers in the pupal cell or chamber (fig. 12). This chamber is a space at the upper end of the gallery which curves out to the inner bark above and contains in the curved portion next to the bark a small quantity of fine, sawdust-like particles of wood. The chamber is 2 or 3 inches in length, being limited at the lower end by a packing of coarse, string- like wood fiber. In the spring the point at which the chamber extends to the inner. bark begins to show from the outside as a slightly depressed, dead spot in the bark. This spot marks the place from which the adult is to issue later, and is especially notice- able on young, smooth- barked trees. THE PUPA. The pupa (fig. 13) is an intermediate form be- tween the larva, or borer, Fic. 8.—Female beetle placing an egg in the tree and the beetle which de- below the-surface of the ground. (Original.) posits the eggs. In this form the insect is of about the same color as the borer, but the shape is greatly changed, the legs, wings, antenne, and other appendages which the adult is to possess being now visible. The insect does not feed while in this stage and is incapable of mo- tion except that of wriggling about in the chamber. It occupies a vertical position in the tree with its head up. The change from the borer to the pupa takes place at the time apple trees are in bloom, the pupal stage covering a period of about three weeks. THE ROUNDHEADED APPLE-TREE BORER. 9 THE ADULT. The borer attains the adult stage 10 days or 2 weeks before it leaves the pupal chamber. When ready to issue it gnaws a circular hole through the bark (fig. 14) and escapes. The beetles average about three-fourths of an inch in length, exclusive of the antenne. The color is light brown above with Fic. 9.—Roundheaded apple-tree borer. Fic, 10.—Roundheaded apple-tree borer. First summer in tree. Natural size. Second summer in tree. Natural size, (Original.) (Original. ) twe broad, white bands, joined in front, extending the full length of the back; the underparts and front of the head are white. The female is larger than the male, the body being thicker and heavier. (Fig. 15.) All the beetles in a given locality issue from the trees within a period of two or three weeks. After they emerge they seek the branches of the trees, where they spend the greater part of their lives 93003°—Bull. 675—15——2 10 FARMERS” BULLETIN 675. resting among the foliage. The females make short flights in search of trees in which to oviposit. Rarely they fly for a considerable distance, but where suitable trees in which to deposit eggs are abun- dant they usually pass their lives within a few rods of the trees from which they issue. (Fig. 3.) The males in seeking their mates make longer and more frequent flights. Both sexes are active by day and at twilight in warm weather, and, although they occasionally fly at night, Fic, 11.—Castings of roundheaded apple-tree borers at base of young apple tree. (Original. ) the hours of darkness are more likely to be spent in quiet among the branches. The adults do considerable feeding on the bark of twigs and on the midribs and stems of leaves (fig. 16), and they also show a fondness for the moisture that is contained in castings thrown from trees by borers still in their larval stage. This habit is not important from the standpoint of any noticeable injury which such feeding does to the tree, but it causes the death of some of the beetles when they THE ROUNDHEADED APPLE-TREE BORER. Lh feed from trees that have been sprayed with arsenical poisons and suggests spraying with arsenicals as a possible means of combating the borers. . When ready to oviposit the female usually crawls down the trunk of the tree to the ground and slits the bark with her mandibles (figs. 4, 7), after which she turns around, inserts her ovipositor into the slit (fig. 5) and deposits an egg, the whole operation occupying about 10 minutes. She may deposit as many as 5 eggs without resting and will then crawl] back up the trunk or move away a short distance over the ground and fly to the branches above or to a neighboring tree. The average life of a beetle is about 40 or 50 days, although indi- viduals occasionally live to be 70 or 75 days of age. NATURAL ENEMIES. All observers ‘agree that wood- peckers destroy great numbers of the borers by drilling into the trees and removing them from their bur- rows. The marks made by these birds in searching for borers may be found in the trunks of trees in almost any infested orchard. In some cases from 50 to 75 per cent of the borers are destroyed in this way. Most of the borers devoured are taken from the pupal cham- ber or while they are making the 1S: 12-—Roundheaded apple-tree bor- s 5 ers in pupal chambers. Position ascent of the trunk preparatory to occupied during winter previous to pupation. It is rather unfortunate mee oe PUMICE eR eta that the birds so often wait until the borers have done the prin- cipal part of their injury to the tree before they remove them. Probably both the hairy and downy woodpeckers feed on the borers. | One hymenopterous parasite, Cenocoelius populator Say, has been reported from Indiana, but in many localities this species is doing very little in the way of holding the borers in check. 12 FARMERS’ BULLETIN’ 675. METHODS OF CONTROL. This insect in its borer stage lives and feeds under the bark where no poisonous or contact sprays or washes can be directed against either its food or its body, and consequently it has always been con- sidered a difficult pest to control. Modern insecticides have not been used so successfully against it as against many other common insect I'ic. 18.—Pupxe of roundheaded apple-tree borer. (Original.) enemies of the orchard. However, there are practicable methods whereby the borers may be destroyed, or oviposition prevented, and injury thus greatly reduced or entirely eliminated, even in orchards that have suffered severely. In the use of these methods timeliness and thoroughness are essential factors, just as they are essential in the processes of combating most insect pests. THE ROUNDHEADED APPLE-TREE BORER. LS WORMING. Removing the borers from trees by the use of a knife and piece of wire, a practice commonly known as worming, is one of the oldest and, when thoroughly done, one of the most effective ways of dealing with this insect. In worming trees the operator should be equipped with a strong pocketknife, a piece of small wire, a vial of carbon bisulphid, a small quantity of cotton batting, and a garden trowel. (Fig. 17.) These articles may be carried very conveniently from tree to tree in a small basket. The knife should have a long, sharp blade and the wire should be bent to form a small hook at one end and a circle or ring at the other. Into the ring a scrap of white or brightly colored cloth should be tied as a safe- guard against losing the wire. The trowel is for use in scraping away from the base of the tree any earth or litter that interferes with a_ close search for castings of the borers. When castings are found the bark should be cut away sufficiently to allow the borer to be traced by its burrows and killed. If the cutting is done with care, and the borer secured, the wound will usually heal without = ric. 14. Adult roundheaded apple-tree borer just F sts erged fr -xit hole i ark. Natural size, noticeable injury to the emerged from exit hole in bark. Natural size ; (Original,) tree. The natural healing tendency of the tree may be assisted by covering the wound with lead paint. During the first few months of its life the borer is easily found and destroyed, but after it has been feeding a year or more the difficulty of locating it is increased, since at that time its burrows extend more deeply into the tree. However, with a little practice one becomes rather adept at securing the borer regardless of its age or the posi- tion it may occupy in the wood. As the borers engage in burrowing in the tree they keep a clear space behind them, and up to the time the pupal cell is being con- structed there is usually nothing to prevent inserting the wire into the exposed end of the burrow and hooking them out. While the 14 FARMERS’ BULLETIN 675, pupal cell is being formed, the burrow below, which up to that time has been kept open, is packed for several inches with wood fiber so that the wire can no longer be used successfully. In all cases where curves or other obstructions in the burrows interfere with hooking the borer out, a little cotton batting dipped in carbon bisulphid should be inserted into the hole and the opening plugged with moist earth. The gas coming from the carbon bisulphid will penetrate all parts of the burrow and will kill the borer. It should be borne in mind that the gas is highly inflammable and that fire should be kept away. In extensive orchards where worming is done on a large scale by promiscu- ous labor some of the help- ers are likely to become careless and overlook or neglect to destroy an occa- sional borer. Every female so overlooked stands a good chance of maturing within a year or two, when it will deposit eggs in a. half dozen or more near-by trees, causing thereby a continued and an increased infestation in that partie- ular part of the orchard. The importance of the following points should be kept in mind by all per- sons who practice this method of borer control: 1. Borers should be re- Fic. 15,—Adult male and female roundheaded yyoved from the trees as apple-tree borer. Male on left, female on ; right. Slightly enlarged. (Original.) soon as possible after hatching. 2. Every borer in the orchard should be found and destroyed. 5. Borers should not be allowed to breed in cultivated or wild host trees growing within at least 200 or 300 feet of the orchard. It is the practice with many orchardists to put off the fall worming of trees until after winter apples are gathered. Observations have shown that this practice permits the borers, which feed rapidly while young, to remain in the trees too long for safety. Even in so short a time small trees may be girdled and killed and larger trees seri- ously injured. In the latitude of West Virginia and Maryland the THE ROUNDHEADED APPLE-TREE BORER. 15 work should be done not later than the Ist of September; farther south it may be done several weeks or a month earlier, and north of the States mentioned the time will be correspondingly later. A second examination should be given the trees the following spring to secure borers from belated eggs or those that may have been over- looked at the fall worming. , The fact that the adult female does not habitually wander far in depositing her eggs (see fig. 3) is greatly to the advantage of the or- chardist who depends on worming to save his trees. When once his Fic. 16.—Twig and leaf of apple gnawed by adult round- headed apple-tree borer. (Original.) orchard and all surrounding host trees are cleared of the borers he is likely thereafter to be troubled very little by new infestations so long as adults are kept from developing within the area. He should continue his examinations of the trees every year, however, to de- tect in time any fresh outbreaks arising from eggs deposited by adults that may occasionally fly into the orchard from a distance. Where this method is used all worthless trees in which the borers can breed, growing within a few hundred feet of the orchard, should 16 FARMERS’ BULLETIN 675. be removed. This would include service (figs. 18, 19), mountain ash, wild crab, and thorn trees in woods, as well as the cultivated fruit trees. PAINTS AND WASHES. Paints and washes of various kinds have frequently been recom- mended for use on the trunks of trees, both to prevent the beetles from depositing eggs and to kill the borers within the trees. Experi- ence has shown that it is easier by such means to prevent the eggs from being laid than to kill the borers. Some orchardists report success by applying pure kerosene to the bark of affected trees at the places where castings show borers to be at work. The kerosene is sup- posed to penetrate the burrow to the insect and kill it. Others have found that this treatment does not destroy enough of the borers to make the remedy worth while, and that in addition the kerosene may kill the bark at the point cf applhi- eation. The danger of injury to trees by the use of kerosene or other mineral oil practically prohibits the use of these substances. Milder solutions, apphed in the same way, while not so likely to injure the trees, are even less fatal to the borers. On the other hand, a heavy ap- plication, made just before the be- ginning of the egg-laying season, of some thick paint that will not injure the trees and that will maintain an unbroken coat on the bark for two Frc. 17.—Tools for use in removing or three months is very effective in Rikaspestipiad Pits oe preventing the female from placing her eggs in the bark. The beetle in slitting the bark with her jaws, preparatory to inserting the egg, will 55) very rarely, if ever, make an opening through such a thick coat of paint. 3efore applying paint for this purpose the earth around the base of the tree should be removed with a garden trowel or hoe to a depth of 3 or 4 inches. Bark scales and adhering earth should then be scraped from the space to be covered, and the paint applied with a THE ROUNDHEADED APPLE-TREE BORER. iN brush in the form of a band around the tree extending about a foot up the trunk and 2 or 8 inches below the level of the ground. After the paint is dry the earth removed in the beginning should be re- placed. The painting may be done more thoroughly and economically by two persons working together on opposite sides of the tree. The deterrent effect of the paint seems to arise from the mechanical barrier it presents rather than from malodorous or distasteful proper- Fic. 18.—Clump of service bushes showing exit holes of roundheaded apple-tree borers. (Original.) ties. The paint should cover the treated portion of the tree in a thick, solid coat, with no cracks or unpainted spaces left, as the beetles will seek cut such openings in which to oviposit. Any non- injurious paint that will form a coat of the nature described will answer the purpose. or yy ew ot an TK RUS 9 i ed . a Pah a w Aq \ ies Rast t Fic. 12.—Pupe of the house fly. About natural size. (From Newstead.) flies were kept alive here for a period of 70 days, a long period, but not sufficient to carry them through the winter. Regular collections of flies were made at the Arlington farm during the winter of 1914-15. No living adult house flies were found after the middle of January until April 30, while Pollenia, which does hibernate in the adult state, could be found in buildings almost any time during the winter, and on warm days they were found outside. On the other hand, there are on record some experiments and ob- servations which indicate that the usual manner in which the house fly passes the winter is in the pupal stage. Bishopp, Dove, and Par- man succeeded in two instances in keeping the species through the winter in the larval and pupal stages. Three barrels of heavily in- 94399°— Bull. 679—15 2 10 FARMERS’ BULLETIN 679. fested manure were covered with'a large screen cage on November 26, 1913. No adults emerged after December 27 until April 16, 1914. and others on May 26, at which time observations were discontinued. This showed that the house fly lived in the larval and pupal stages for periods of from five to six months. In another case they were kept alive in the immature stages from December 16, 1913, to April 4,1914. This was at Dallas, Tex. CARRIAGE OF DISEASE. The body of the house fly is thickly covered with hairs and bristles of varying lengths, and this is especially true of the legs. Thus, when it crawls over infected material it readily becomes loaded with germs, and subsequent visits to human foods result in their contam1- nation. Even more dangerous than the transference of germs on the legs and body of the fly is the fact that bacteria are found in greater numbers and live longer in the alimentary canal. These germs are voided, not only in the excrement of the fly, but also in small droplets of regurgitated matter which have been called “ vomit spots.” When we realize that flies frequent and feed upon the most filthy substances (it may be the excreta of typhoid or dysentery patients or the dis- charges of one suffering from tuberculosis), and that they may sub- sequently contaminate human foods with their feet or their excreta or vomit spots, the necessity and importance of house-fly control is clear. Tn army camps, in mining camps, and in great public works, bring- ing together large numbers of men for a longer or shorter time, there is seldom the proper care of excreta, and the carriage of typhoid germs from the latrines and privies to food by flies is common and often results in epidemics of typhoid fever. And such carriage of typhoid is by no means confined to great temporary camps. In farmhouses in small communities. and even in badly eared for portions of large cities, typhoid germs are carried from excrement to food by flies, and the proper supervision and treatment of the breeding places of the house fly become most im- portant elements in the prevention of typhoid. In the same way other intestinal germ diseases are carried by flies. Asiatic cholera, dysentery, and infantile diarrhea are all so carried. Nor are the disease-bearing possibilities of the house fly limited to intestinal germ diseases. There is strong circumstantial evidence that tuberculosis, anthrax, yaws, ophthalmia, smallpox, tropical sore, and parasitic worms may be and are so carried. Actual laboratory proof exists in the case of a number of these diseases, and where lacking is replaced by circumstantial evidence amounting almost to certainty. HOUSE FLIES. bE} NATURAL ENEMIES. The house fly has a number of natural enemies. The common house centipede (fig. 13) destroys it in considerable numbers; there is a small reddish mite which fre- quently covers its body and gradu- ally destroys it; it is subject to the attacks of hymenopterous para- sites in its larval and pupal condi- tion; and it is destroyed by preda- tory beetles at the same time. The most effective enemy of the house fly, however, is a fungous disease known as L’mpusa muscae, which carries off flies in large numbers, particularly toward the close of the season. The epidemic ceases in December, and, although many thousands are killed by it. the remarkable rapidity of de- velopment in the early summer months soon more than replaces the numbers thus destroyed. PREVENTIVE AND CONTROL - MEASURES. THE USE OF SCREENS. A careful screening of windows and doors during the summer months, with the supplementary use of sticky fly papers, is a pre- ventive measure against house flies known to everyone. As regards screening it is only necessary here to emphasize the importance of keeping food supplies screened or otherwise covered so that flies can gain no access to them. This ap- ples not only to homes, but also to stores, restaurants, milk shops, and as = <> a ee. a ae | \ a \ \ Fic. 13.—The house centipede (Scutigera forceps) : Adult, natural size. (After Mailatt.) the hike. Screening will, of course, have no effect in decreasing the number of flies, but at least it has the virtue of lessening the danger of contamination of food. 12 FARMERS’ BULLETIN 679. FLY PAPERS, POISONS, AND TRAPS. In the effort to destroy flies that have gained access to houses the use of sticky fly papers is very common. Another way is to expose in shallow dishes a mixture of formalin and milk or water, sweetened with a little sugar (1 teaspoonful of commercial formalin to 1 teacup- ful of water or milk). This is most effective when no other liquids are accessible to the flies. Formalin diluted in this manner is not poisonous to man and will not injure fabrics. In this respect it is much safer than the fly poisons containing arsenic. Burning of fresh pyrethrum powder is also effective in killing flies in rooms. Flytraps may be used to advantage in decreasing the number of flies. There are many kinds on the market, and as a rule the larger ones are the more effective. These should be placed on the outside of houses, stores, stables, etc. Bananas, sugar and vinegar, milk, and beer will be found to be attractive baits under most circumstances. The use of flytraps has been enthusiastically advocated by Prof. C. F. Hodge, not only because of the immediate results, but because of the chances that the flies may be caught before they lay their first batch of eggs, and thus the possible number of future generations will be greatly reduced. From what was said above in regard to the preoviposition period it will be apparent that flytraps will be more effective in this respect during the spring and autumn months than during midsummer. The use of fly papers, poisons, and traps are at best only temporary measures. The most logical method of abating the nuisance is the elimination or treatment of all breeding places. It would appear from what we know of the life history and habits of the common house fly that it is perfectly feasible for cities and towns to reduce the numbers of these annoying and dangerous insects so greatly as to render them of comparatively slight account. CONSTRUCTION AND CARE OF STABLES. In formulating rules for the construction and care of stables and the disposal of manure the following points must be taken into con- sideration. In the first place, the ground of soil-floor stables may offer a suitable place for the development of fly larve. The larve will migrate from the manure to the soil and continue their growth in the moist ground. This takes place to some extent even when the manure is removed from the stables every day. Even wooden floors are not entirely satisfactory unless they are perfectly water-tight. since larve will crawl through the cracks and continue their develop- ment in the moist ground below. Water-tight floors of concrete or masonry are therefore desirable. HOUSE FLIES. 4.3 Flies have been found to breed in surprising numbers in small accumulations of material in the corners of feed troughs and mangers, and it is important that such places be kept clean. FLY-TIGHT MANURE PITS OR BINS. The Bureau of Entomology has for some years advised that manure from horse stables be kept in fly-tight pits or bins. Such pits can be built in or attached to the stable so that manure can be easily thrown in at the time of cleaning and so constructed that the manure can be readily removed. The essential point is that flies be prevented from reaching the manure, and for this reason the pit or bin must be tightly constructed and the lid kept closed except when the manure is being thrown in or removed. There is no doubt as to the effectiveness of this method when the necessary precautions are taken, especially if the manure is removed at frequent intervals. FREQUENCY WITH WHICH MANURE SHOULD BE REMOVED. Another point must be considered in deciding the question as to how often the manure should be removed. In this connection it should be borne in mind that when the larve have finished feeding, they will often leave the manure and pupate in the ground below or crawl some distance away to pupate in débris under boards or stones and the lke. Hence the manure should be removed before the larve reach the migratory stage; that is to say, removal is neces- sary every three days, and certainly not less frequently than twice per week during the summer months. . The dark curved object within is the larva just before pupating. The complete life cycle of members of this group of eee may be passed in as short a period as 19 days, but during cool weather Fic. 1.—The dog flea: a, Egg; 6b, larva in cocoon: c, pupa; d, adult; e, mouth parts of same from side; f, antenna; g, labium from below. 6b, c, d, Much enlarged: a, e, f, 9, more enlarged. (From Howard.) or under adverse conditions the total period from egg to adult may extend considerably over a year. HOW LONG THE ADULT WILL LIVE. The length of life of the mature flea varies much in different species and also under different atmospheric conditions. During lic. 2.—The European rat fea: Larva. Greatly enlarged. (Author’s illustration. ) hot, dry weather, and when no animals upon which to feed are present, the duration of life is exeremtly short—two ‘to five days When allowed to feed on blood, which is the only food taken by the adults, they may live from a month to almost a year. During sum- 4 FARMERS’ BULLETIN 683, mer probably the average longevity of the human flea without food is about two months, of the dog flea somewhat less, and of the stick- tight flea still less. ABUNDANCE OF FLEAS IN RELATION TO SEASON, CLIMATE, AND OTHER CONDITIONS. In the northern part of the United States nearly all fleas pass the winter in the immature stages, while in the more southern latitudes some of them are present on hosts throughout the winter months. In general, however, these insects are never as abundant during winter and spring as they are in summer and fall. Rainfall and the amount of moisture in the atmosphere have much to do with flea breeding. As a rule rainy summers are productive of outbreaks of fleas, and extremely hot, dry weather tends to check their breeding. This condition is brought about by the fact that the larva and pupa require a certain amount of moisture for suc- cessful development, and the adults also live longer when there is a proper degree of moisture present. It is not intended to convey the idea that fleas require very moist places in which to breed. As a matter of fact, excessive moisture in the breeding places is as detri- mental as excessive dryness. It is common knowledge that fleas occur in greatest abundance in sandy regions. This is explained by the fact that the sand maintains a more uniform moisture condition and thus permits the immature stages of the flea to develop with greater success. The sand also offers some protection to the adults and renders heavy rains less destructive to all stages of the flea present on the soil. FLEAS AS PESTS IN THE HOUSEHOLD. As has been pointed out,' in the eastern part of the United States the dog flea is the species of greatest importance as a household pest. Many instances have been brought to the attention of the Bureau of Entomology in which houses, particularly those vacated for some time during the summer months, have been found to be literally overrun by these pests. In portions of the South and West the human flea (figs. 8 and 4) is the one primarily responsible for house infestations. Although the host relationship of these two species is somewhat different, the same methods of control are applicable, for the most part, to both. 1 Howard, s. O. House Fleas. U. S. Dept. Agr., Bur. Ent., Cir. 108, 4 p., 2 fig., Feb. 11, 1909. FLEAS AS PESTS TO MAN AND ANIMALS. 5 The conditions which give rise to outbreaks in houses, particularly in the case of the dog flea, are usually these: Pet dogs or cats are kept about the household during the spring and early summer, and great numbers of eggs are deposited upon them by the fleas. These eggs are scattered about the floors and soon hatch into minute maggots which feed upon the vegetable and animal matter under carpets and mattings and in cracks. During this time the house has been closed up and the breeding allowed to proceed unmolested, so that at about the time the occupants return the fleas have reached Wie. 3.—The human flea: Adult female. Greatly enlarged. (Author's illustration.) the adult stage. In the absence of other hosts they are exceedingly hungry and ready to attack man or any animals which are accessible. Some infestations of residences come from breeding places beneath the houses. The fleas in these cases are usually furnished by stray animals which sleep under the buildings. The immature stages develop in the accumulation of dust and vegetdble matter in the beds of these animals. Instances are not uncommon where such in- festations may extend to lawns, barnyards, and, in fact, all over the premises, although as a rule the center of infestation is in some one definite place frequented by animals. 6 FARMERS’ BULLETIN 683. The infestations of the human flea are usually less heavy than in the extreme cases above mentioned, and the breeding places are often more widely extended. A number of instances in the Southern and Central-Western States have come to notice where hogs appear to have been the source of gross infestations of the human flea. The adult fleas feed on the hogs, and breeding takes place in the beds of these animals. In some Ss TS v4 Fic. 4.—The human fiea: Adult male. Greatly enlarged. Note the difference in the shape of the abdomen of the male as compared with that of the female (fig. 3). (Author’s illustration.) instances the source of infestation is in the hog runs, but more usually it is derived from hogs sleeping under houses. FLEAS INJURIOUS TO POULTRY AND DOMESTIC ANIMALS. Fortunately the higher domestic animals are comparatively free from flea attacks. Horses, cattle, sheep, and goats are very seldom annoyed, although a few instances_have come to our attention in which the sticktight flea infested horses. Hogs are infested to some extent, but seldom heavily enough to do any damage. FLEAS AS PESTS TO MAN AND ANIMALS. 1 THE STICKTIGHT FLEA. The sticktight flea, or southern chicken flea, is probably the most important of our live-stock 1n- festing species. This form at- tacks a number of different hosts, including poultry, dogs, cats, and some wild animals. As has been stated, the adult fleas re- main during the greater part of their lives attached to the host animal. On dogs and cats they are largely found on the ears, particularly along the edges. In the case of poultry infestations fleas are most com- mon on the heads of the hosts, where they are to be seen in groups or patches. This habit of attaching in clusters seems to be well marked, and an in- 5.—Head of rooster infested with the sticktight flea. Somewhat reduced, (Au- thor’s illustration.) fested fowl often may be recognized at a considerable distance by the dark flea-covered areas about the eyes, comb, and wattles. Fig- Itc. 6.—The sticktight flea: Adult female. (Author’s illustration. ) Much enlarged. ure 5 illustrates the usual mode of in- festation on a chicken’s head, and figure 6 shows one of the fleas much enlarged. When the fleas are excessively abundant they may be found in similar patches on the neck and various parts of the body. This flea is most common and of greatest importance in the Southern and Southwestern States. It has been reported as injuri- ous to poultry as far north as Kansas. The injury is most marked in young chickens, which when fairly heavily infested often die 8 FARMERS’ BULLETIN 683. quickly. Older fowls are more resistant, but have been known to succumb to very heavy infestations; and certainly the fleas materi- ally reduce egg production, retard the growth of fowls, and diminish their size. The eggs are deposited by the adult flea while it is attached to the host. They fall to the ground under the roost in chicken houses or under sheds frequented by the poultry and there continue to develop. When dogs and cats are infested the immature stages develop largely in the material used by them for beds. A few other species of fleas are occasionally found in poultry houses. Some of these may be normally bird-infesting species, while others are at home in the houses of domestic poultry. Infestations by these fleas have been reported from several places in the Northern States, particularly in the Northwest. The presence of the fleas is usually first detected by the adults getting on the bodies of persons entering chicken houses. These fleas do not remain attached to the host continuously as does the sticktight flea. They are seldom of any great importance and may be controlled by the same methods outlined on pages 13 and 14. DOG AND CAT FLEAS. Dogs and cats are infested by two very closely related species of fleas. and these appear to feed more or less interchangeably on the two hosts, as well as occasionally on man and other animals. While they cause these hosts much annoyance and, as has been pointed out, are also responsible for the infestation of dogs by tapeworms, seri- ous injury seems to be rare. However, in the case of valuable dogs and cats it is often desirable to rid them of fleas, and in all cases where these animals are closely associated with man the control of the fleas upon them is of importance. As will be seen by comparing figure 1 with figure 6, the dog flea is quite different from the stick- tight flea in structure as well as in size. The adults do not remain attached to the host in one place, but the life history is not vastly different from that of the sticktight flea. Breeding takes place in similar materials in situations occupied by the host animals. Mr. Theodore Pergande, working with the dog flea at Washington, D. C., found the life cycle from egg to adult to be completed within 17 to 37 days. It is thus seen that a great number of fleas might be bred in and beneath an unoccupied house in a comparatively short period. Both of these species have a very wide distribution, being found in practically all parts of the world where dogs and eats are found. 1 The cat flea is known scientifically as Ctenocephalus felis Bouché, and the dog flea as Ctenocephalus canis Curtis. The human flea also is not uncommonly found on dogs and cats. FLEAS AS PESTS TO MAN AND ANIMALS. 9 FLEAS IN RELATION TO BUBONIC PLAGUE. During recent years bubonic plague has been introduced into the United States on both the Pacific and Gulf coasts. The infestation in California persisted for a number of years, although it was closely held in check through the efforts of the Public Health Service and the State board of health. The disease around San Francisco not only persisted among the rats, but gained a foothold among ground _squirrels in the counties adjacent to San Francisco Bay. A strenuous fight is being waged against rats in all of the Pacific ports and against ground squirrels in the territory where the disease has become estab- lished among these rodents. During the year 1914 the disease broke out in New Orleans, but strict quarantine measures and an energetic campaign against the rats kept the malady from spreading and limited the number of human cases. While the plague situation is now well in hand it is important that all have a general knowledge of the essential steps in controlling the disease. The prevention of the introduction of bubonic plague depends to a considerable extent upon quarantine regulations at our ports of entry, but it is of even greater importance that united effort be put forth to control the rats in the seaport towns. The work should not stop here, as it is of importance that concerted action be taken against rats and ground squirrels throughout the entire country. It may be gathered from what has been said that the control of bubonic plague depends almost entirely upon the destruction of the rat population. This is essential in that the disease always starts by gaining a foothold among the rats, and as these animals die and the fleas leave them and attack man the human cases of plague begin. In addition to the importance of rat control from the standpoint of disease prevention there is every reason to wage war against these pests on account of their importance as destroyers of agricultural and other products. It has been estimated that the loss in the United States due to rats exceeds $100,000,000 annually. The principal methods of combating these rodents* are rat proofing, trapping, poisoning, and destruction by natural enemies. With the reduction in numbers of rats and mice the various species of fleas which infest them and which in turn may play a part in carrying bubonic plague are greatly reduced in numbers. The clean- ing up of the breeding places of rats and the destruction of their nests will also accomplish the extermination of a large number of fleas in the immature stages. Some of the methods of trapping fleas mentioned under “ Means of Repression ” will aid in destroying those 1 The methods of rat control are discussed in Farmers’ Bulletin 369, U. S. Department of Agriculture, by Mr. D. E. Lantz, of the Bureau of Biological Survey. 10 FARMERS’ BULLETIN 683. which may have fed on rats and are therefore dangerous as regards disease transmission. . Persons resident in districts where plague occurs among the ground squirrels should remember that there is danger of infection from the bites of fleas which infest these animals. MEANS OF REPRESSION. Certain general principles regarding the control of fleas are appli- cable to nearly all species, but some modifications of the methods employed are necessary for different species and under the different conditions in which they exist. METHODS OF COMBATING HOUSEHOLD INFESTATIONS. As has been pointed out, the dog flea and the human flea are the two most important species invading the habitations of man. It has also been suggested that the adult fleas feed more or less on cats and dogs and that the immature stages develop in the cracks of floors and beneath houses. It is at once apparent that two steps are necessary to cope with the pest: (1) The destruction on the host of the adults which are producing the eggs, and (2) the clearing out of the imma- ture stages which are breeding in or under the house. THE DESTRUCTION OF FLEAS ON CATS, DOGS, AND HOGS. One of the most successful methods of killing fleas on cats and dogs is to wash the animals thoroughly in a tub containing the proper pro- portion of a saponified coal-tar creosote preparation, of which there are a number on the market, known as “ stock dips,” ete. The animal should be thoroughly scrubbed, making sure that the fleas on the head are well soaked, as many rush there to get away from the parts that are covered with the solution. After the animal has been in the bath for about 5 or 10 minutes it may be removed and allowed to dry. In the case of cats, especially if tender skinned, the preparation may be washed out of the fur with soap and warm water soon after the animal is taken out of the solution. In addition to the destruction of all fleas present, this accom- plishes the cleansing and deodorizing of the fur and also aids in the healing of any wounds which are present. Other methods of destroying fleas on cats and dogs have been recommended. Among these the careful rubbing into the hair of powdered naphthalene or moth balls has been found effective. Pyrethrum or Persian insect powder is used in the same way. Both of these materials stupefy the insects and cause them to come to the FLEAS AS PESTS TO MAN AND ANIMALS. i surface of the hair or actually drop out. The animals should be treated on papers spread on the floor and the insects burned after the dusting is completed. Fleas on hogs may be destroyed by dipping the animals in a vat containing some of the creosote dips as used for the hog louse or by sprinkling crude petroleum on them when they are eating. CONTROL OF HOSTS. In order to avoid the infestation of houses, it is important to keep all animals from beneath dwellings. In such situations breeding may progress rapidly, and it is very difficult to treat the breeding places. If fleas are continuously annoying about the household, it is often desirable not to admit cats and dogs at all, but to provide regular sleeping quarters for these animals out of doors and prevent flea breeding by methods suggested in the following paragraph. Stray cats and dogs should not be encouraged about the premises. In towns and cities the enforcement of the dog-tax law and the destruction of all untagged animals will tend greatly to reduce house infestations. It is also desirable to keep different kinds of animals which are subject to flea infestation separated, and care should be exercised that infested animals are not brought to clean premises and that infested poultry are not placed with a clean flock. DESTRUCTION OF FLEAS IN IMMATURE STAGES. Following the ridding of infested animals of adult fleas, it is important to destroy the immature ones which are constantly be- coming full grown and reinfesting animals and annoying man. In household infestations it is usually found that the breeding takes place in the cracks of floors or beneath carpets or in rooms which are not frequently swept, but which may be visited by pet dogs and cats. The carpets and rugs should be removed, the floors thoroughly swept, and all of the dust thus obtained burned, as it contains many of the eggs and maggots of the fleas. The floor should then be scrubbed with strong soapsuds or sprinkled with gasoline, taking care to avoid having fires about during this procedure. After the floor coverings are thoroughly aired and beaten they may be re- turned, but it is desirable before putting them down to sprinkle the floor with naphthalene crystals or pyrethrum powder. In flea-infested regions it is advisable to avoid the use of mattings and carpets. These may be supplanted by rugs or oiled bare floors. This permits frequent sweeping of the floors and makes the destruc- tion of the immature stages easier if an infestation becomes estab- lished. 12 FARMERS’ BULLETIN 683. Among other methods for destroying the fleas in houses the fol- lowing have been tried and recommended: Scatter 5 pounds of flake naphthalene over the floor of an infested room and close tightly the doors and windows for 24 hours. After this time the naphthalene may be swept into another room, and so on, thus making the treat- ment inexpensive. The free use of alum, both in the powdered form sprinkled over carpets and rugs and by dipping papers in an alum solution and placing them under the rugs, is said to give satis- factory results. The fumigation of houses with sulphur fumes or hydrocyanic-acid gas also accomplishes complete destruction. In ad- dition to killing all of the fleas, rats and mice are destroyed by these last-mentioned methods. In using sulphur the infested building should be closed up tightly and the material used at the rate of 4 pounds to each 1,000 cubic feet of space. If the immature stages have been destroyed by the methods mentioned above, 2 to 3 pounds of sulphur per 1,000 cubic feet of space will be sufficient to destroy the adults. The sulphur is made into a cone shape in a good-sized pan or kettle and placed in a larger pan containing water to avoid danger of fire from the heat generated. it 2, 400 72 24 24 ming sass 2,900 87 29 29 Servant’s....- 1, 200 36 12 12 Basement sy. ccetec setae ce Ute ocee eases eets Hall ones ane 2, 000 60 20 20 Kitchen... ..-. 1, 800 54 18 18 Mo tal ars £47 2 oe ha, hee Aes 3 he Stee Sh DU LN eg 37, 800 | 1,138 378 378 The house is prepared for treatment by seeing that all the win- dows are closed and calked, if of loose construction, with wet paper or cotton batting tucked tightly into the crevices. Gummed paper strips are obtainable for this purpose and may be pasted over the crevices in the doors and windows, making the room practically gas-tight. As the building must be aired by opening the windows from the outside, those selected to be opened should be examined to see that they pull down easily, and if too high to be reached from the ground should be provided with strong cords reaching to the ground that they may be easily opened from below. They should be opened before closing for the last time in order to test the strength of the cord and should not be pasted up or calked. The fireplace flues in the different rooms should be stuffed with paper and the reg- isters closed. Carpets and rugs should be cleared away from the floor as far as possible to prevent their being burned should the acid spatter or boil over. For generators, stoneware or crockery jars having a capacity of 4 gallons are preferable and may be used with a charge of up to 3 pounds of cyanid. One of these vessels should be placed in each room, with the exception of large rooms requiring a charge of more than 3 pounds of cyanid, when the charge may be divided. One vessel will suffice for each 3,000 or 4,000 cubic feet, preferably the former amount. Under each of these vessels a larger vessel or a rather thick carpeting of old newspapers should be placed, and care must be exercised to see that none of the vessels is cracked, on account of the danger of breakage from the heat generated by the process. Deep vessels are more satisfactory for the experiment than the washbasins often used, but the latter are always available and will serve the purpose. Deeper vessels give greater depth to the HYDROCYANIC-ACID GAS AGAINST HOUSEHOLD INSECTS. 5 water and acid and accelerate the chemical action, and there is less danger of spattering. Whenever the room is of such size that much more than 3 pounds of cyanid must be employed for it, it is perhaps better to make two charges of half size for such room. PROCESS OF FUMIGATION. In the process of generating the gas the water may be measured in a glass beaker indicating ounces, or, for convenience, in a pint cup, and poured into the generators. The acid, measured in the same receptacle, is then slowly and gently poured into the water to avoid splashing or boiling. For all ordinary purposes 1} pints of the acid and 3 pints of water are sufficient for each pound of sodium cyanid. The acid should never be placed in the generators first, as advised by some writers, since experience shows that this is dangerous, spatter- ing being almost certain to follow. When the acid is poured into the water in the jar an ebullition of vapor sometimes arises. Consider- able heat is also developed by the addition of the acid. When the cyanid, which previously should be broken into pieces the size of an egg, is finally dropped into the combined acid and water mixture bubbling takes place similar to that produced by a red-hot iron dipped into cold water. The generation of hydrocyanic- acid gas, the most poisonous gas in common use, begins at once. The gas is colorless and has an odor which has been likened to that of peach kernels. This odor is decidedly metallic, like that produced by striking two pieces of metal together, or of metal against stone. If the fumes are inhaled in any considerable quantity they are almost certain to prove fatal; hence the necessity of extreme care and the advisability of the presence of two intelligent operators in this work. It is even advisable, especially when the first fumigation is under- taken, that one who has had experience with this method of fumi- gation be present to give directions. The measuring and preparation of the water and acid in the fumi- gating jars should be undertaken in a room with a tile or concrete floor if possible, as the strong acid used is apt to injure wooden floors or carpets should spilling occur. The jars may then be distributed to the different rooms and a bag containing the requisite cyanid placed by the side of each. The house is now in readiness to be fumigated. Coats and hats and everything needed outside must be removed, and preferably two persons should then go to the top of the house, taking different rooms on the same floor to expedite the process, and place the bags contain- ing the cyanid gently into the vessels to receive them. The chemical action will begin at once, but the gas will not rise to any extent for a few seconds or a quarter of a minute, and there is ample time to leave the room quickly without danger of breathing the gas. Having 6 FARMERS’ BULLETIN 699. finished the garret or top floor, the operators should pass rapidly to the next, and so on to the basement, making their exit through the lower door to the street. Hydrocyanic-acid gas is lighter than air, and consequently rises; therefore the operation must be begun at the top of the house. The house should be locked from the outside and, if necessary, a warning sign put up to caution against entrance. The preparation of the different rooms, getting their cubic con- tents, placing the vessels, and preparing the charges, in a house of the size indicated in the foregoing table, will take from two to three hours, and this much time must be allowed for. The house should remain closed, for the gas to become fully generated and do its work, for from 4 to 6 hours at least—preferably, however, and to get the greatest efficiency, for 24 hours. Better results are claimed for a warm temperature, say, 70° F. or above, than in a temperature as low as 50° F. or below. Under 50° most insects become torpid, and the effective action of the chemical will be diminished, especially in very low temperatures. At the close of the operation the doors may be opened and the windows lowered or opened from the outside, and after an hour’s airing the house may be entered, if no strong odor of gas is detected, and opened up even more thoroughly, if possible, to allow a complete airing for several hours. The house should not be reinhabited until all traces of the odor of the gas have disappeared. This odor, as stated before, has been compared to that of peach kernels. The contents of the generating jars should be poured into the sewer trap, or disposed of in some place where they will not be a source of danger, and the jars thoroughly cleaned. THE CYANID AND GAS A DEADLY POISON. In the use of hydrocyanic-acid gas for household fumigation we must not for a single instant lose sight of the fact that we are dealing with one of the most poisonous substances known; that the accidental eating of a small portion of cyanid will necessarily be fatal; and | that the inhalation of a few breaths of the gas will asphyxiate, and, if rescue be not prompt, have a fatal termination. It is much better, therefore, if fumigation be contemplated, to put the work in the hands of some one who has had experience, if such a person be available; if not, to consider carefully all the recommendations and precautions in this bulletin and become thoroughly familiarized with them before undertaking the experiment. While the writers thus strongly emphasize the dangerous and even fatal qualities of this gas when breathed by human beings, it is worthy of remark that in the thousands of operations which have been carried on with this gas in different parts of the world only HYDROCYANIC-ACID GAS AGAINST HOUSEHOLD INSECTS. ¥ three cases of fatal accidents to human beings have been recorded. These were due to extreme carelessness in its use. In one case the operator went back into the house after having dropped the bags and closed the building for some time. The abundant experience which has been gained by the different members of the force of the Bureau of Entomology and many others in the fumigation of dwell- ing houses has demonstrated that all danger is easily overcome by care in conducting the operation. In all the house-fumigation work which has been done during the last 10 years no aceident has occurred, except in one or two instances the burning of rugs in attempting to set off charges in too small vessels and a case of head- ache where a few whiffs of much diluted gas had been accidentally breathed. It follows, from what we have just said, that there may be danger from fumigating one house in a row of houses separated only by party walls, the other houses being inhabited. Unnoticed cracks in a wall would admit the poisonous gas to the neighboring house. In such a case a householder must consult his neighbors. In isolated houses, however, with the precautions indicated, the operation will be a safe one. The fact that birds resting on the ridge of houses in which the gas was being liberated have been killed by the ascending fumes indicates also that where the house to be fumigated immediately ad- joins a higher structure to which the gas may possibly gain entrance there may be some danger to the occupants of the higher structure. Single apartments or rooms in buildings should not be fumigated except when the whole building can be vacated during the operation. In case of contiguous houses of loose construction an arrangement should be made so that the adjoining houses also may be vacated during fumigation. In handling the acid great care should be used in pouring it from the bottle and in putting it into the vessels to avoid spattering on the hands or face, since it will burn rapidly through the skin, and should it spatter into the eyes would cause serious inflammation or loss of sight, or if on the clothing it would burn a hole in the garment. Should a drop fly to the hands or face, bathe the part promptly and freely in water, and the same also for garments or the carpet. It is further desirable to have at hand a bottle of ammonia to neutralize the acid should it spatter on clothing. The handling of the dry cyanid is not accompanied by any danger if there be no open wound on the hand, but it is advisable to wear an old pair of gloves in breaking up the cyanid and putting it into the 1One of the fatalities mentioned in a preceding paragraph resulted from the fumiga- tion of a basement in an apartment house not only without seeing that these apartments and the entire building were vacated and closed during the operation, but without even warning the occupants in the apartments above. 8 FARMERS’ BULLETIN 699. sacks, these gloves to be afterwards burned. The fact that the cyanid has a superficial resemblance to sugar adds to the danger of keeping it about the premises, and it is much better at once to bury deeply or throw down the sewer trap any left-over cyanid. SUMMARY OF METHOD. The general directions for treatment may be briefly summarized as follows: (1) Prepare tabular statement designating room capacity and amount of chemicals for each compartment and secure the chemicals and vessels for generating the gas. (2) Arrange for the opening of doors and windows from the out- side at the conclusion of the fumigation and close all registers, fire- places, and other openings. Do necessary calking and remove carpets and rugs and moist food material and any metallic objects which are likely to be tarnished. (3) Place the generating vessels in each room with a thick carpet- ing of old newspapers under each. (4) Break up the cyanid out of doors and place it in thin paper sacks containing charges suited to the amounts to be used. in the different rooms. (5) Measure into each of the generating jars the proper amount of water and afterwards add the acid slowly in the proper amount to each of the jars. (6) Take the cyanid in bags in a basket and place the bags con- taining the proper amount alongside of the generating jars in each room. (7) Start at the top of the house and place the cyanid gently, so as not to spatter, into each jar and quickly leave the room. As soon as the upper floor is finished go to the next lower, and pass in this manner from floor to floor until the basement is reached and exit is made through the lower door. If two persons work together in this operation they should both be on the same floor together, taking different rooms. (8) The following day, or after the completion of the fumigation, open the windows and doors from the outside and let the house ventilate for an hour before entering it. (9) After the house is thoroughly ventilated and the odor of the gas has disappeared, empty the jars in a safe place, preferably through the sewer trap, and wash them thoroughly and repeatedly before using them for any household purpose. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1916 HIV. INSEOTS, UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS’ BULLETIN Wasuinerton, D. C. 7Ol1 January 15, 1916 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE BAGWORM, AN INJURIOUS SHADE-TREE INSECT.’ By L. O. Howarp and F. H. CH1iTTENDEN. CONTENTS. Page. Page. General appearance and nature of BEL OGRE OL Sara g SS ete eee ae 3 SUC Ken ene 2 a ee 1 Habrtsrand life history=—— 222225 5 Original home and present distribu- Natiralvenemics2= 2. oe = eer et i 2 EU CTNC HRS Stet = Sa Re eee ae ee 7 LEGO 2 2 ee ee ee ee GENERAL APPEARANCE AND NATURE OF ATTACK. Shade trees, shrubs, and hedges, and in particular evergreens, are much subject to injury by a caterpillar which has a curious habit of crawling about on the infested trees in a baglike case, whence its com- mon name of bagworm or basket worm.' In the shelter of these cases the insects undergo all their transformations, after which the bags remain attached to the plants for some time and are conspicuous ob- jects on leafless trees and shrubs in late autumn and in winter. Like the tussock moth? and the fall webworm® this species is preemi- nently a pest on trees and shrubs along streets and in parks and private grounds of cities and towns and even more than these is sub- ject to fluctuation in numbers. It is, however, more limited in dis- tribution than the two insects mentioned and not found as a rule 1Thyridopteryx ephemeraeformis Haworth; order Lepidoptera and family Psychide. 2 Hemerocampa leucostigma 8. & A. ® Hyphantria cunea Dru. Nore.—This bulletin is suitable for distribution in the southeastern portion of the United States. 11432°—16 y FARMERS’ BULLETIN ‘01. north of southern New York and the central portions of Pennsyl- vania and Ohio. South of these points it is in certain years very troublesome and the subject of much complaint. Such a year was => 1907, when the bagworm attracted greater atten- tion than any other tree defoliator. Numerous complaints were received of injuries in the region mentioned, especially from the States of New Jer- sey, Pennsylvania, Maryland, Virginia, West Vir- ginia, Ohio, Indiana, and Illnois. The natural enemies of this insect (see p. 7) were compara- tively scarce, and there is a strong possibility of a recurrence of injuries in the years to come. The general appearance of the bagworm is shown in figure 1, which illustrates the caterpillar when nearly full grown in its characteristic bag. When removed from its bag it looks as shown in figure Fic. 1.—Bagworm 2, a, which represents the full-grown larva. At (Thyridoptery® this period in its development it may attain a ephemeraeformis). J Natural size. length of about three-fourths of aninch. The body ee eee is soft in texture and dull brownish or blackish, while the head and thoracic segments are horny and whitish, mottled with dark brown. Fic. 2.—Bagworm (Thyridopteryx ephemeraeformis) : a, Full-grown larva ; b, head of same; c, male pupa; d, female pupa; e, adult female; f, adult male. All somewhat enlarged. (From Howard.) N. B.—The various stages are in reality a trifle longer than they are shown by the hair lines. ORIGINAL HOME AND PRESENT DISTRIBUTION. The bagworm is unquestionably native to North America. It abounds in the Southern States, except in the immediate Gulf region, THE BAGWORM. 3 but is found farther to the north, and there are indications that it has gradually spread into this territory from more southern regions. The map (fig. 3) which shows the region in which injury by the bagworm has been reported up to the year 1907 by black areas, and again during the two years 1913 and 1914 by shaded areas, as authen- ticated by the files of the Bureau of Entomology, may indicate that the species tends to spread toward the south and west. This apparent tendency, however, may be due merely to the planting of more trees in the more thickly populated towns and cities in such States as Oklahoma. FOOD PLANTS. The bagworm, although a very general feeder, displays a par- ticular fondness for evergreens of all kinds, especially for arbor- ND. IND. io i po \ \ ALA. \ GA ' \ LA ' ' ' ! a 1 ‘ x 1 ' ' ' =" H DBIAWFAH4 Fic. 3.—Map showing, by black areas, localities in which injury by the bagworm has been reported up to 1907 and, by shaded areas, those in which injury was reported in 1913 and 1914. (Original.) vite (fig. 4); hence it seems probable that one or the other of these was its original or normal food plant. The species becomes exceedingly abundant every few years, and at such times it may be found on shade, orchard, and forest trees of nearly every kind. It is fond of willows and maples, particularly the silver maple and its _varieties and the related boxelder; it is also fond of the poplars and mulberry, less so of the elms, and apparently still less so of the oaks. It feeds more or less freely, however, on most other trees and shrubs, and even on many low-growing semiwoody plants, such as elder, _mallow (Hibiscus), and ragweed.t' Thus in the absence of its choice food plants it is able to subsist on the foliage of almost any of the 1 Ambrosia trifida. FARMERS’ BULLETIN 101. (Authors’ illustration.) Arborvitse infested by bagworms. Fic. 4. THE BAGWORM. 5 plants of the character enumerated which may be available, but it does not seem to live on grasses and herbaceous plants generally. HABITS AND LIFE HISTORY. The bagworm overwinters in the egg stage within the old female bag, and for this reason hand picking in wintertime is an efficacious remedy. In the late spring the young hatch from the eggs, crawl out upon the twigs, make their way to the nearest leaf, and imme- diately begin to feed and to construct cases or bags for themselves. They spin a_ large quantity of silk, and attach to it for addi- tional strength and protection bits of leaf or twig, evidently at- tempting to disguise the nature of the case as well as to strength- en it. The larva is re- markably soft-bodied, except for its head and strong thoracic plates, and it is nec- essary that the soft abdomen should have some protection. The construction of the bag of an allied species of similar hab- its has been described as follows: The young larva cuts off with its jaws a small fragment of leaf which it places between its front legs, Fig. 5.—a, Newly hatched bagworm before making its case; 6, same, just beginning case; c, same, with its gradually forming a case nearly completed; d, completed case, insect con- cealed within; e, larva after first molt. Highly magni- fied. (Authors’ illustration.) pile fastened loosely with silk. When the pile becomes a transverse tangle about as long as the body, it is fastened at each end loosely to the surface upon which it rests; then the caterpillar, after placing itself at right angles, dives under the 6 FARMERS’ BULLETIN 101. mass, turning a complete somersault, so that it lies on its back, bound down by the fillet. It then twists around and stands upon its feet, having its neck under a sort of yoke. It makes the yoke into a com- plete collar, adding bits to each end until the circle is complete. Then row after row of fragments is added until the case becomes a hollow cylinder. One end is then closed up, and the inside lined with a tough coating of silk, the case being then extended upright and fastened at one end. When it is fully completed, the larva crawls away with the case carried upright like a cap on the up- turned end of its body. Figure 5, a—c, shows stages in the construction of the case and d a completed case made by the young larva, tightly appressed to the flat surface, the larva being concealed within. Such bags may fre- quently be found on leaves, and are quite puzzling to the unin- itiated until the larva pokes out its head and slowly walks off. As the caterpillar grows, the case is con- stantly enlarged, bits of twigs and any other small objects being used to ornament the outside, and these ob- jects will vary with Fic 6.—Bagworm at (a, b,c) successive stages of growth. the kind of tree upon c, Male bag; d, female bag, About natural size. (From 2 é Howard.) which the caterpillar is feeding. While the larva is small, it carries its case erect, but when it is larger the case hangs down (see fig. 1). The larval skin is cast four times, and dur- ing the molting the mouth of the bag is kept closed with silk. There is a small opening in the extremity of the bag through which excre- ment and cast skins are pushed. The male bags reach a length of about an inch, while those of the female are much larger. Toward the end of August, about Washington, D. C., the larva completes its growth, attaches its bag firmly by a silken band to a twig, strengthens it inside with an additional layer of silk, and within this retreat, which now becomes its cocoon, transforms to pupa with its head downward. The pupal period lasts about three weeks, and then the adult emerges. The male chrysalis works its way out of the lower opening, THE BAGWORM. v6 and the winged moth issues through the cracking skin, leaving the chrysalis hanging from the bag, as shown at ¢, figure 6. The chrys- alis of the female does not push its way at all out of the bag, but the skin cracks and the female gradually works her way partly out of the chrysalis skin, her head reaching the lower end of the bag (fig. 6,d). The males fly about seeking the bags of the females, and when one is found in which the head of the female is near the end, showing that she has emerged from her chrysalis skin, the male mates with her. The female then works her way back into the chrysalis : : : : : Fic. 7.—Itoplectis inquisitor: Fe- skin, gradually filling it with eggs until = male from side. Enlarged. more than half of it is filled, scattering ‘?™°™ Mower) in among the eggs some of the sparse hairs from her body. Having done this, she forces her shriveled body out of the opening, falls to the ground, and dies. The eggs remain in this way until the following spring when they hatch as previously described. There is thus only one gen- eration annually. NATURAL ENEMIES. Although apparently well protected from the attacks of birds by its tough case, the bagworm is somewhat extensively parasitized by several forms of ichneu- mon? and chaleis flies, most of them species which affect also similar tree-feed- ing caterpillars. ‘ REMEDIES. Fic. 8.—Allocota thyridopterigis. Much enlarged. (Authors’ illustration.) When the bagworm oc- curs upon deciduous trees it can be controlled by hand picking the bags in the winter, but when it affects evergreen trees it is practically impossible to apply this 1(Pimpla) Itoplectis inquisitor Say (fig. 7), (Pimpla) Itoplectis conquisitor Say, and (Hemiteles) Allocota thyridopterigis Riley (fig. 8). 2 Spilochalcis mariac Riley (fig. 9), Chalcis ovata Say (fig. 10), Dibrachys boucheanus Ratz. (fig. 11), and Habrocytus thyridopterigis Ashm. (fig. 12). Certain of these species are undoubtedly hyperparasitic ; that is, parasites of the bagworm parasites. 8 FARMERS’ BULLETIN 101. remedy with profit unless the plants are badly defoliated. Therefore, for the treatment of evergreens, spraying is a necessity. The methods of controlling shade-tree pests in cities and towns? are in part applicable to this species. COLLECTING THE BAGS. One of the most important remedies consists in gathering the bags with the contained insects by hand and either burning them or preserving them to liberate the useful parasites which have been previously mentioned. This work may be facilitated by the use of a 12-foot pole pruner or similar appliance. Where the trees are very tall it will be necessary to use a long ladder. For best results the cooperation of neighbors who are troubled with the same pest should be secured. Con- siderable immunity from future injury will result by care in the employment of this method. It is particularly useful where only a few trees are infested. The bags are such conspicuous ob- Fic 9.—Spilochalcis mariae. About four times jects on defoliated or bare trees Spa reed \ Steg ellen) in winter that it is not at all dif- ficult to detect them, but in cases where comparatively few insects are present on evergreen trees they are not so easily seen. ENCOURAGING THE PARASITES. When many trees are infested it is advisable to keep the hand- picked bags for a considerable time in receptacles, such as barrels covered with netting, preferably wire netting, so that the numerous beneficial parasites of the pest will be able to issue in the spring and assist in the control of the bagworm the following year. One or two holes bored in the bottom of the barrel or box will prevent water from accumulating and drowning the insects. Where the bags can be ‘placed in piles in an open space or inclosure distant from trees and free from disturbance, the young insects, having very limited powers of locomotion, will soon perish of starvation, as they will not be able to find the trees or shrubs after they hatch. SPRAYING WITH ARSENICALS. On evergreens, where the bags are more or less difficult to find, Bul. No. 99, 32 p., 11 fig., 1899. This publication may be had free on application to the Department of Agriculture. THE BAGWORM. 9 of this method under such circumstances was given by a former Government entomologist at a conference on the gipsy moth in 1891. He said that he once tried to protect a cedar tree not more than 6 feet high, upen his own grounds at Washington, by hand pick- ing. He worked during two consecu- tive months picking off small bags from that tree, the progeny of not more than two females. Almost daily he went to the tree and found fresh specimens which he had overlooked the day before. For evergreen trees, therefore, an arsenical spray is the best remedy. Injury by the bagworm on large trees has been absolutely stopped by spraying with Paris green at the rate of 1 pound to 150 gallons of water, the trees being completely rid of larve. It is easier to reach the bagworms on evergreen than on large- leaved deciduous shade trees, such as Fic. 10—Chalcis ovata: Adult. En- maple and elm, but if carefully car- Be state guar EL Mit, ried out, spraying will result in the destruction of the bagworms, so that the collection of the bags in winter will not be necessary. Arse- nate of lead at the rate of 1 pound of the prepared paste form to from 25 to 50 gallons of water will be found even more effective than the Paris green, as its greater adhesive- ness renders it less likely to_ be washed off by rains, which in some seasons fre- quently occur al- most daily at the time when the larve are begin- ning to work. Fic. 11.—Dibrachys bowcheanus: Adult female and antenna of Arsenate of lead male. Much enlarged. (From Howard.) is not at all likely to produce scorching of the foliage of shade or ornamental trees or shrubs. Its natural adhesiveness is enhanced by the addition of about the same quantity by weight of resin-fishoil soap as of the arsenical used. 10 FARMERS’ BULLETIN 101. The question as to the best spraying apparatus to be used is an im- portant, one, the prime object being to destroy the insect without injuring the plant; the second, to avoid useless waste of the poison. Hand pumps and sprayers are unsatisfactory. One of the best types of orchard sprayer is desirable. This usually consists of a tank of about 100 gallons capacity equipped with a pump driven by a gaso- line engine, mounted on a strong cart or wagon fitted with the 2 proper length of hose and drawn by either one or two horses. Fre- quently one operator is enough, but two are bet- ter for most purposes, especially in the case of high trees. In regard to nozzles, the older types, such as Vermorel and Bor- Fig. 12.—Habrocytus thyridopterigis. Greatly enlarged. deaux, mav be used, but (From Howard.) ; the new solid spray or Worthley type (fig. 18) is preferable. In case tall shade trees in valuable parks or woodlands are to be treated—trees such as spruce, cypress, hemlock, and willow, as well as maples—high-power spray- ers are preferable. The type which has given the most satisfactory results in the gipsy-moth work can develop sufficient power to carry a stream which breaks into a fine mist in the air, and this is very satisfactory in rapid treatment. With such a sprayer it is not neces- sary to climb trees or to use small lines of hose or turrets. In the treatment of a great number of trees a greater strength, namely 2 or 3 pounds of arsenate of lead to Fic. 15.—Solid spray or Worthley type of nozzle, and cut-off. f (Original.) 50 gallons of water or Bordeaux mixture, is desirable, as the bagworms do not feed in masses and the poison must be directed so as thoroughly to coat and remain on the foliage where it will be eaten with the leaves. The treatment should be thorough and the application made evenly in order to secure the best results. Recent inquiry has elicited the in- formation that arsenate of lead is being used with the highest power sprayers even at the rate of 10 pounds to 50 gallons of water, which THE BAGWORM. ii we consider an unnecessary expenditure. Moreover, if two or three applications are made—and this is often desirable in case this or other insects continue to injure the trees—it is almost certain to affect inju- riously or destroy some forms of tender leafage if made at this strength. The best time to apply either of the arsenicals mentioned, as in the case of most insects, is at about the time when the eggs hatch or a day or two afterwards. 12 FARMERS’ BULLETIN 101. PUBLICATIONS OF U. S. DEPARTMENT OF AGRICULTURE RE- LATING TO INSECTS AFFECTING SHADE AND ORNAMENTAL TREES. AVAILABLE FOR FREE DISTRIBUTION. Danger of General Spread of the Gipsy and Brown-tail Moths through Imported Nursery Stock. (Farmers’ Bulletin 453.) : The Gipsy Moth and the Brown-tail Moth, with Suggestions for Their Control. (Farmers’ Bulletin 564.) The Catalpa Sphinx. (Farmers’ Bulletin 705.) The Huisache Girdler. (Department Bulletin 184.) Report on the Gipsy-moth Work in New England. (Department Bulletin 204.) Dispersion of Gipsy-moth Larvee by the Wind. (Department Bulletin 273.) FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS. Three Insect Enemies of Shade Trees: (Elm Leaf-beetle, White-marked Tussock Moth, and Fall Webworm.) (Farmers’ Bulletin 99.) Price, 5 cents. The Brown-tail Moth and How to Control It. (Farmers’ Bulletin 264.) Price, 5 cents. The Gipsy Moth and How to Control It. (Farmers’ Bulletin 275.) Price, 5 cents. The Gipsy Moth in America. (Bureau of Entomology Bulletin 11, n.s.) Price, 5 cents. The Locust Borer. (Bureau of Entomology Bulletin 58, Pt. I.) Price, 5 cents. Additional Data on the Locust Borer. (Bureau of Entomology Bulletin 58, Ptlbie)) Sericesoreents: Report on Field Work against the Gipsy Moth and the Brown-tail Moth. (Bu- reau of Entomology Bulletin 87.) Price, 35 cents. The Importation into the United States of the Parasites of the Gipsy Moth and the Brown-tail Moth. (Bureau of Entomology Bulletin 91.) Price, 65 cents. The Dispersion of the Gipsy Moth. (Bureau of Entomology Bulletin 119.) Price, 20 cents. The Imported Elm Leaf-beetle. (Bureau of Entomology Circular 8, revised.) Price, 5 cents. The Cottony Maple Seale. (Bureau of Entomology Circular 64.) Price, 5 cents. The Catalpa Sphinx. (Bureau of Entomology Circular 96.) Price, 5 cents. The Bagworm. (Bureau of Entomology Circular 97.) Price, 5 cents. The Common Red Spider. (Bureau of Entomology Circular 104.) Price, 5 cents. The Leopard Moth. (Bureau of Entomology Circular 109.) Price, 5 cents. The Green-striped Maple Worm. (Bureau of Entomology Circular 110.) Price, 5 cents. The Oak Pruner. (Bureau of Entomology Circular 130.) Price, 5 cents. Food Plants of the Gipsy Moth in America. (Department Bulletin 250.) Price, 10 cents. : WASHINGTON : GOVERNMENT PRINTING OFFICE : 1915 FARMERS’ BULLETIN Wasuinaton, D. C. 705 FrBruary 16, 1916 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE CATALPA SPHINX.: By L. O. Howarp and F. H. CHrrreNDEN. INTRODUCTION. Our native species of catalpa, the common or eastern catalpa? and the hardy or western species,? are comparatively free from insect attack. Such common shade-tree pests as the bagworm* and fall webworm® occasionaliy feed upon the leaves, but apparently do so only in the absence of food more palatable to them. There is one insect, however, the larva or caterpillar of the catalpa sphinx (fig. 1, b, c, e, f, A),1 which feeds normally and exclusively on the foliage of these trees and in some seasons does very considerable injury, often completely stripping the leaves from individual trees and sometimes from an entire grove. (Fig. 2.) Owing doubtless to the increased planting of these trees outside the regions in which they are found in the wild state, this insect has extended its natural range, and its injury is more widespread now than formerly. e DESCRIPTION. The catalpa sphinx in its active feeding stage is a caterpillar fully 8 inches in length. It is very variable in color, there being a light and a dark form, as in the case of some related species. The prevail- ing colors are yellow and black, and this, combined with the large size of the insect, makes it a conspicuous object on infested trees. The complete life history by stages or periods of growth is well illus- trated in figure 1. 1Ceratomia catalpae Bdvy.; order Lepidoptera, family Sphingidae. 2 Catalpa catalpa. 8 Catalpa speciosa. + Thyridopteryx ephemeraeformis Haw. * Hyphantria cunea Dru. Novre.—This bulletin is of interest throughout the United States wherever catalpa trees occur. 15606°—Bull. T05—16 y) FARMERS’ BULLETIN 1705. ‘J. ewig 9A Fic. 1.—Catalpa sphinx (Ceratomia catalpae) : a, Egg mass: b, b, newly hatched larve; ¢, larva one-third grown ; d, dorsal view of joint of c; e,f, two differently marked, nearly full-grown larve ; g, dorsal view of joint of [> h, full-grown dark larva ; i, dorsal view of joint of same; j, pupa; k, moth: 1, egg, enlarged. All natural size, except 1. Marx del. THE CATALPA SPHINX. 3 The parent of the caterpillar is a large grayish-brown hawk moth, marked as shown in figure 1,/. It has a large, heavy body and pow- erful wings which measure 3 inches from tip to tip when spread. It lays its eggs In masses, in which respect it differs from other hawk moths. An egg mass is shown in the illustration at @ and an indi- vidual egg at 7. The young caterpillars are lighter colored than the mature ones, being pale yellow. Two striking variations of the larva Fic. 2.—Catalpa trees showing excessive defoliation by the catalpa sphinx. (Original.) in the later stages are shown at f and e, while h represents the com- monest dark form of caterpillar. The larve have a stout black horn near the hind end of the body. ORIGINAL HOME AND PRESENT DISTRIBUTION. The known distribution of the catalpa sphinx at the present time (1915) is shown in figure 3. This insect is strictly a North American 4 FARMERS’ BULLETIN 105. species, and its range was given in 1888 as from “ Virginia to Florida; westward to the Mississippi; as far north as Indiana.” It is common in Virginia, Maryland, and Ohio, and of late years it has extended its range northward on the Atlantic coast and has been received from several localities in southeastern Pennsylvania, New Jersey, Ohio, Kentucky, and Dela- ware. It has spread northward in Dela- ware and has greatly increased in numbers where it was formerly rare. Its northward range appears to be limited in the West by Illinois* This species was observed in Alabama in 1883, was received from Denison,.‘Lex:s im 1889, and was re- ported from Arkan- sas in 1900. By 1906 Map showing the known distribution of the catalpa it had become estab- BiGas. sphinx in the United States in 1915. (Original. ) lished at Elberon and Bloomfield, \. J., the latter, westward and a little north of New York City, being the northernmost point of which we have knowledge of its occurrence in the East. It has since been reported from Burlington, N. C., Jericho Springs, Mo., and Wetmore, Tenn. LIFE HISTORY AND HABITS. The catalpa sphinx is subject to considerable fluctuation in numbers. For one, two, or even several years it will not be seen in a given locality and will then suddenly appear in large numbers, completely defoliating the trees and covering the ground beneath with larval excreta. It is interesting to cbserve that John Abbot, who collected the type specimens in Georgia, mentioned the fact more than a hun- dred years ago that fishermen who inhabited the borders of the swamps hunted for these larvee as the best bait for catching fish, and 1The range of its food plants is as follows: From the Gulf of Mexico in western Florida, and on the rivers in Alabama and Georgia, westward and northward along the Mississippi and its southern tributaries in the great delta formation to above the mouth of the Ohio; thence up the Wabash and White rivers of Indiana to near Vincennes. This was formerly taken by entomologists to indicate also the range of the catalpa sphinx. Published records, however, were lacking until recently to show its general occurrence west of Florida and Georgia along the gulf. THE CATALPA SPHINX. 5 it is said that this bait is so esteemed for this purpose in some parts of Florida that the catalpa is often cultivated for no other purpose than to attract the insect. The eggs, as has been stated, are laid in masses, and the young larve feed in groups for some time. The capacity of the species for multi- plying may be judged from the fact that an egg mass in the collection of the United States National Museum contains nearly 1,000 eggs. The mass is not compact, however, and is but slightly fastened to the underside of the leaves. Sometimes the eggs are laid in smaller masses on the stems and branches. The larve molt four times, becoming variable in their markings as they grow older. In the extreme South the insect is reported as being found in all stages during the summer, and there are three or four generations a year, the last generation wintering in the pupal stage beneath the ground and giving forth the moths the following March. In the summer, according to observations made in Florida, the time occupied by a complete generation is about six weeks. Around Washington, D. C., at Coalburg, W. Va., and probably everywhere in its southern range, there are two generations annually. NATURAL ENEMIES. A number of parasitic insects attack and lull the catalpa sphinx. Apanteles congregatus Say, a common, widespread, and very gen- eral parasite of sphinx caterpillars throughout the eastern United States, attacks this species quite as freely as it does the hornworms of tobacco and tomato. Unfortunately, this parasite is in turn attacked by other parasites, two species of which? are recorded. These last, fortunately, do not seem to be generally abundant, hence the beneficial parasite flourishes in spite of their attacks. Apanteles congregatus is a minute, four-winged, wasplike insect which lays its eggs in the sphinx caterpillar. Its larve—white, maggotlke creatures—de- velop within the body of the caterpillar, and when full fed and ready for transformation each individual eats a hole through the skin of the caterpillar and spins its little white cocoon on the outside. Two hundred or more such cocoons may be seen on the body of a single caterpillar. After a few days the winged parasites issue from the cocoons to lay eggs and produce another generation of larvee. (Apanteles) Microplitis catalpae Riley, which appears to be espe- cially a parasite of the genus to which the catalpa sphinx belongs, is also an enemy of this species, although, like the Apanteles, it is some- times itself attacked by other parasites.? 1 Mesochorus aprilinus Ashm. and Hemiteles mesochoridis Riley MS. 2 Hypopteromalus tabacum Fitch and (Holcopelte) Horismenus microgastri Ashm., 6 FARMERS’ BULLETIN 105, Two common species of tachina flies? attack the larva of the catalpa sphinx. These are general parasites of butterflies and moths, the former infesting 27 distinct species, the latter 22. A few birds prey upon the caterpillar, but most of them evidently find it when full grown a rather tough morsel, the skin being espe- cially thick and resistant and the insect a very muscular one, so that, in fact, it is difficult to crush one with the end of a cane. Among the birds which have been re- corded as destroying this insect are cuckoos, the cat- bird, and the Baltimore oriole. REMEDIES. There are several meth- ods by which the catalpa sphinx may be readily de- stroyed. The caterpillars may be gathered by hand, the folage of the trees may be sprayed with ar- se ae tae a ele AR ase ak eee Miers i senical eee the PEE Adult with puparium at right and enlarged MAY be destroyed by spad- antenna at left. (From Howard.) ing the ground around the tree trunks in the fall, and, indirectly, the sphinx may be destroyed by protecting ‘the parasitic insects which attack it. HAND PICKING. Owing to its large size, the caterpillar is easily seen and can be con- trolled by hand picking. In the case of large trees a long ladder and a 12-foot pole pruner or similar device will be necessary in this work. SPRAYING WITH ARSENICALS. Where the caterpillars are injurious to trees of considerable height, rendering hand picking difficult, or where they occur in such abun- dance as to render probable the complete defoliation or stripping of the tree, the application of an arsenical spray is the best method for their control. Advantage may be taken of the gregarious habit of the young caterpillars by watching rather closely for their appearance in the spring, and if the leaves are observed to be eaten in any particular place, promptly applying an arsenical spray. The arsenicals ordinarily used in the control of shade-tree insects are arsenate of lead and Paris green. If properly applied, neither of 1 Phorocera claripennis Macq. (fig. 4) and Frontina frenchii Will. THE CATALPA SPHINX. these will be injurious to the leaves. In the preparation of these materials for spraying. the desired quantity of the chemical, usually 1 pound of Paris green or 3 pounds of arsenate of lead to 50 gallons of water, is weighed out and thoroughly mixed in a pail or other small container with a gallon or two of water. This mixture is then poured into a 50-gallon barrel, the remainder of the water added, and after having been strained through fine copper gauze for the removal of particles which might clog the nozzles, the spray is ready for use. The application of the arsenate of lead or Paris green spray in com- bination with Bordeaux mixture is desirable, since the foliage of the catalpa is frequently infected by leaf spot? and by other similar diseases which may be controlled by the application of Bordeaux mixture. Moreover, in the presence of Bordeaux mixture no burning is likely to result, even to the most delicate foliage, through free arsenic in the Paris green or arsenate of lead used in the spray mixture. Bordeaux mixture may be prepared for this purpose as follows: In a barrel containing 25 gallons of water hang 6 pounds of blue vitriol or bluestone in a cloth sack. Four pounds of fresh stone lime should then be slaked in a pail or other container and water added until of about the consistency of whitewash. This mixture should then be poured into a second barrel with 25 gallons of water. In the usual preparation of spray mixtures 50-gallon barrels are used. After the bluestone has dissolved and the lime has been added to its respective quantity of water the two barrels may then be raised and simultaneously poured into a third one, the mixture being well stirred at the same time. After the prepa- ration of the Bordeaux mixture according to this formula the requi- site amount of Paris green or arsenate of lead is added and thoroughly stirred into the mixture. A sprayer suitable for the control of the catalpa sphinx caterpillar, or other larve feeding on the leaves of catalpa or other trees of similar size and habit, might consist of one of the smaller power outfits such as are used in orchard spraying, or one of the large double-action hand pumps capable of furnishing a spray mixture to from three to five nozzles of the removable steel-disk type, using the large opening, at about 100 pounds pressure. With the aid of a 10 to 12 foot tower on the wagon and an exten- sion rod on the hose line, it will be possible to treat trees from 35 to 40 feet in height, which is about the maximum for the ordinary catalpa under cultivation. For trees of greater height a three-eighths to one- fourth inch nozzle of the Worthley type, supplied by a pump capable of delivering from 30 to 50 gallons a minute at a pressure of from 300 to 400 pounds, will be found necessary. Trees as much as 100 feet in 1 Phyllosticta catalpae. 8 FARMERS’ BULLETIN 1705. height have been sprayed in this manner from an ordinary sprayer tower. A high-power spraying outfit of the type used against the gipsy moth is shown in figure 5. Such a powerful stream will dis- ay de os a ee * Pig. 5.—High-power spraying outfit for treating large caterpillars like the gipsy moth and catalpa sphinx. (from Burgess and Rogers.) lodge many of the caterpillars. Particular attention is called to the upper end of the stream, in the illustration, where it breaks into a mistlike spray. THE CATALPA SPHINKX. 9 DESTRUCTION OF THE PUP. Where the caterpillars have been so abundant as to affect the trees, it will pay as a precaution for the following year to spade up the ground thoroughly and disintegrate it in the fall so as to destroy the pupee, which will be found concentrated under the surface of the ground in the immediate vicinity of the trunk. PROTECTING THE PARASITES. The second or tast generation, which appears in September and October, is largely destroyed by parasites which are frequently very abundant just as the oldest caterpillars are beginning to reach full growth. At this time the parasites, which have been previously men- tioned, issue from the bodies of their host and spin large masses of white cocoons on the backs of the caterpillars. These masses are so large that they can he seen at a considerable distance against the black stripes of the host insect. It is not advisable to destroy the caterpillars at this stage, as the parasites are very beneficial and in ordinary seasons will reduce the numbers of the sphinx caterpillars so that they will not do much harm the following season. Where the caterpillars can be easily gathered it will pay to pick them from the leaves and transfer them to barrels or large boxes covered with wire netting. This will prevent the caterpillars from issuing or falling a prey to birds or other animals, and will insure the issuance of the parasites through the meshes, thus encouraging their good work. A few holes should be bored in the bottom of the barrels or boxes used, small enough to prevent the caterpillars from crawling through them into the ground. This will prevent the accumulation of water after rains, which might drown the insects or set up putrefaction in the mass. COOPERATION. If the cooperation of neighbors who have catalpa trees growing on their premises can be secured, this caterpillar can be largely con- trolled for several years in succession. PUBLICATIONS OF U. S. DEPARTMENT OF AGRICULTURE RELAT- ING TO INSECTS AFFECTING SHADE AND ORNAMENTAL TREES AND HARDY SHRUBS. AVAILABLE FOR FREE DISTRIBUTION. Danger of General Spread of the Gipsy and Brown-tail Moths through Imported Nursery Stock. (Farmers’ Bulletin 453.) The Gipsy Moth and the Brown-tail Moth, with Suggestions for Their Control. (Farmers’ Bulletin 564.) San Jose Seale and Its Control. (Farmers’ Bulletin 650.) The Bagworm, an Injurious Shade-tree Insect. {(Farmers’ Bulletin 701.) The Leopard Moth: A Dangerous Imported Insect Enemy of Shade Trees. (Farmers’ Bulletin 708.) Rose-chafer. (Hntomology Circular 11.) The Locust Borer. (Entomology Circular 83.) Euonymus Seale. (Entomology Circular 114.) Oyster-shell Scale and Scurfy Scale. (Entomology Circular 121.) San Jose Scale and Its Control. (Entomology Circular 124.) The Huisache Girdler. (Department Bulletin 184.) Report on the Gipsy-moth Work in New England. (Department Bulletin 204.) Dispersion of Gipsy-moth Larve by the Wind. (Department Bulletin 2738.) FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS. Three Insect Enemies of Shade Trees (Elm Leaf-beetle, White-marked Tussock Moth, and Fall: Webworm). (Farmers’ Bulletin 99.) Price, 5 cents. The Brown-tail Moth and How to Control It. (Farmers’ Bulletin 264.) Price, 5 cents. The Gipsy Moth and How to Control It. (Farmers’ Bulletin 275.) Price, 5 cents. San Jose Seale, Its Occurrences in United States, with Full Account of Its Life History and Remedies to be Used Against It. (Entomology Bulletin 3, n. s.) Price, 10 cents. The Gipsy Moth in America. (Entomology Bulletin 11, n. s.) Price, 5 cents. Some Insects Injurious to Violet, Rose, and Other Ornamental Plants. (Ento- mology Bulletin 27, n.s.) Price, 10 cents. Principal Insects Liable to be Distributed on Nursery Stock. (Entomology Bulletin 34.) Price, 5 cents. Some Insects Injurious to Forests. (Entomology Bulletin 58.) Price, 20 cents. San Jose or Chinese Scale. (Entomology Bulletin 62.) Price, 25 cents. Report on Field Work against the Gipsy Moth and the Brown-tail Moth. (Ento- mology Bulletin 87.) Price, 35 cents. The Importation into the United States of the Parasites of the Gipsy Moth and the Brown-tail Moth. (Entomology Bulletin 91.) Price, 65 cents. The Red Spider on Hops in the Sacramento Valley of California. (Hntomology 3ulletin 117.) Price, 15 cents. The Dispersion of the Gipsy Moth. (Entomology Bulletin 119.) Price, 20 cents. Rose Slug-caterp lar. (Hntomology Bulletin 124.) Price, 5 cents. The Imported Elm Leaf-beetle. (Mntomology Circular 8.)° Price, 5 cents. How to Control the San Jose Scale. (Entomology Cireular 42.) Price, 5 cents. The Cottony Maple Scale. (Entomology Circular 64.). Price, 5 cents. The Catalpa Sphinx. (Hntomology Circular 96.) Price, 5 cents. The Bagworm.. (Entomology Circular 97.) Price, 5 cents. Common Red Spider. (Hntomology Circular 104.) Price, 5 cents. Rose Slugs. (Entomology Circular 105.) Price, 5 cents. The Leopard Moth. (Entomology Circular 109.) Price 5 cents. The Green-striped Maple Worm. (Entomology Circular 110.) Price, 5 cents. The Oak Pruner. (Entomology Circular 180.) Price, 5 cents. Dying Hickory Trees: Cause and Remedy. (aitariniges Circular 144.) Price, 5 cents. Flour Paste as Control for Red Spiders and as Spreader for Contact Insecticides. (Entomology Circular 166.) Price. 5 cents. Rose Aphis. (Department Bulletin 90.) Price, 5 cents. Food Plants of the Gipsy Moth in America. (Department Bulletin 250.) Price, 10 cents. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1916 yikes i ¢ iy As Te a m0 Hp’ rm TS Sst ead 5 be! UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS’ BULLETIN Wasuincton, D. C. TOS FEBRUARY 14, 1916 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE LEOPARD MOTH:' A DANGEROUS IMPORTED INSECT ENEMY OF SHADE TREES. By L. O. Howarp and F. H. Cu1rrenDENn. INTRODUCTION. Along the Atlantic seaboard from eastern Massachusetts to southern New Jersey, and in the Hudson River Valley, shade and ornamental trees and shrubs of many kinds, with the exception of evergreens, are severely injured ‘by the larva or caterpillar of the European leopard moth. Around such centers as Boston and New York, and in the State of New Jersey, this insect constitutes a most serious menace to the- growth of shade trees. The larva of the leopard moth does not feed on the foliage, as do most of our shade-tree caterpillars, but bores into the branches and feeds upon the living wood. It usually begins opera- tions in twigs and small branches and trunks; this work has the effect of girdling and so weakens the wood that the portion beyond the injury is often broken by heavy wind storms, while in the case of severe attack, especially to young trees, the growth of the tree is checked and death frequently follows. Attack is not confined solely to shade and ornamental plants, but orchards also are often injured. DESCRIPTION. The leopard moth derives its name from the spotted appearance of the adults as illustrated at @ and } in figure 1. There is a great difference in size between the sexes, the female (a), which is a heavy- bodied moth and a very feeble flier, being much the larger. The male (2), on the other hand, has a more slender body, which insures ready flight, and is further distinguished from the female by the fact that its antenne, or feelers, are broad and feathery. The wings are semi- 1 Zeuzera pyrina Fab.; order Lepidoptera, family Cossidae. Synonyms: Zeuzera aesculi L. and Z. decipiens Kirby. Norr.—This bulletin is of interest to growers of shade and ornamental trees, especially in the New England and North Atlantic States. 18681°—Bull. TO8—16 2 FARMERS’ BULLETIN 708. transparent and white, thickly dotted-with blackish spots which are more or less distinctly tinged, giving them a dark-blue or greenish ‘ast. The thorax is white and has six large black spots and one small one, this last being in the center. The abdomen is white, with dark crossbands. The female has a wing spread of something over 4 inches, while that of the male is much less. The eggs are oval and salmon colored. The larva, which is the form that inflicts the injury, is a fleshy, erublike caterpillar of pale-yellow color, very frequently with a pinkish tinge, especially when reaching full growth. The head, me Letettig tel! | SOUNERIEDAAULBRERLEmeaEeant: || Fic. 1.—The leopard moth (Zeuzera pyrina): a, Adult female; b, adult male; ec, larva; d,empty pupal ease. Enlarged. (Authors’ illustration. ) thorax, and plates on the hind end of the body above are brownish black, and the entire surface of the body is sparsely hairy and cov- ered with large and prominent tubercles arranged as shown in figure 1, c, which illustrates the larva in natural position when at work in a tunnel which it has constructed in the solid hving wood. When ~ the larva has completed its growth it is fully 2 inches in length. The pupa, or chrysalis, to which the full-grown larva changes, is very similar to that of other wood-boring caterpillars. On its head is a sharp protuberance which helps it in pushing its way partly out of the burrow preparatory to the emergence of the moth. The THE LEOPARD MOTH. 3 appearance of the pupa is shown in figure 1 at d, which illustrates the empty pupal case projecting from the burrow, as the moth has left it. ORIGINAL HOME; SPREAD AND PRESENT DISTRIBUTION. The leopard moth, like so many other dangerous pests, is a Eu- ropean species which has been accidentally introduced into the United States in comparatively recent years. Its Old World distri- bution, as recorded, is central and southern Europe, southern Sweden, southwestern Africa, Algeria, northern Morocco, and the western portion of Asia Minor. This species was introduced into the United States sometime prior to 1879; in this year a hving moth was captured in a spider’s web at Hoboken, N. J. In 1887 it was seen at Newark, N. J., but was not actually recorded as occurring in this country until the following year. In 1890 the moths were observed at electric lights at Orange, N. J. In 1894 its destructive ravages were recognized in Central Park, in New York City. Fortunately the spread of this insect, particularly in the immedi- ate vicinity of New York City, has been very slow, a fact which may be attributed to several causes: (1) The slow and feeble flight of the female, (2) the dominance of sparrows and squirrels in large cities, causing our native birds, such as woodpeckers, to be driven to the country, where they destroyed the moths, and (3) the bowl-shaped electric-lght globes, open at the top and closed at the bottom, which were formerly in general use in our large cities. The males are strongly attracted to brilliant lights, and many were captured and perished in these globes in earlier years. Specimens were collected at Bridgeport, Conn., in 1901. The species now occurs on Staten Island and has spread on Long Island well beyond the confines of greater New York. Southward it was reported a pest, in 1901, at Ocean Grove, N. J., and by 1905 was re- corded at Kensico, N. Y., 25 miles north of New York City. By 1907 it was captured at New Haven, Conn. In 1908 it appeared in injurious numbers in the vicinity of Boston, Mass., where it seriously attacked the large elms on the Harvard University campus, and has since spread to more distant localities, specimens having been re- ceived from Lynn and from the island of Nantucket. It has been received from at least one locality in Rhode Island. Other towns and cities are indicated on the map (fig. 2), on which the southward limit, Woodbury, N. J., is shown. On the occasion of a visit to New York City in recent years the junior writer was unable to find this insect or any evidence of its injury in the parks of Manhattan and Harlem. In side streets in the 4 FARMERS’ BULLETIN 1708. vicinity of the parks, however, there were signs of extensive injury, and a number of trees had been removed, evidently because of death due to borer attack. Inquiry of the State entomologist and others failed to elicit any information in regard to new localities. The species has not been found in Pennsylvania so far as can be deter- SN ears SeOEE a Pic. 2.—Map showing known distribution of the leopard moth in the United States in 1915. (Original.) mined, nor has it spread to any extent from the localities which have been mentioned. Information has been received that this species is less serious in its attacks to trees in the vicinity of New Haven, Conn., than it was six or eight years prior to the date of this publication. Taking THE LEOPARD MOTH. 5 everything into consideration, it would seem that the species, while distributed along the coast, will, in time, be greatly reduced in this region, probably by parasites and other natural enemies, and will very gradually spread inland as it is now doing. FOOD PLANTS. In its Old World home the leopard moth is recorded as living on a considerable number of common trees, including elm, lime or lin- den, ash, beech, birch, walnut, oak, chestnut, poplar, alder, and, rarely, horse-chestnut. Among orchard trees it is reported to injure pear, apple, plum, and other fruit trees. In the United States it attacks all of these trees and in addition practically all of the maples, ash, mountain ash, tulip tree, dogwood, aspen, and willows, such shrubs as privet and lilac, and honeysuckle. A list of 83 trees and shrubs which this larva has been actually ob- served to attack was compiled in 1894; 77 of these were observed in the public parks of New York City alone. A later list contains 125 species and varieties. It will be seen by the list of food plants already presented that the number could be almost indefinitely extended, particularly in reser- vations like Central Park, New York City, and Prospect Park, Brook- lyn, where special effort has been made to bring together a great variety of trees and shrubs. The insect will attack practically all forms of woody plants which are of suitable size for its purpose, with the exception of evergreens. LIFE HISTORY AND HABITS. In Europe the moths make their first appearance during July and August, but in this country they appear as early as May and continue issuing from the injured wood until late in September. The female ready for egg laying, being particularly heavy, is unable to fly very far or very high. She deposits her eggs singly and in groups of three to four or more, and as many as 800 eggs laid by a single moth have been counted. The eggs are generally inserted in crevices in the rough bark of trees. The larve hatch in about 10 days, penetrate the wood, frequently entering the nearest crotch, but also boring in at other points, and burrow tunnels into the heart or pith of twigs and the heartwood of the larger branches or trunks. When a larva has grown too large for the branch in which it is feeding it crawls out and enters a larger one. In a single tree 6 inches in diameter as many as six larve were ob- served, any one of which would have been able ultimately to destroy the tree if not removed; in fact, six to eight borers to the tree have been reported as an average in a badly infested location, and in one 6 FARMERS’ BULLETIN 108. instance 84 were found in a single tree. By the time the larve within have attained full growth, infested limbs of a certain size are likely to break off, especially during or after a severe storm, for the full-grown larva in many cases girdles the branch. The manner of girdling is shown at the top of the section of wood illustrated in figure 3. In 1893, after every storm in Central Park immense num- bers of limbs were seen, some entirely broken off and others still hanging to the trees. The larva when fully mature transforms to the pupa within its burrow, the change beginning to occur during the second May after the hatching of the eggs. The larva thus requires nearly two years to complete its growth. The pupa, by means of the sharp protuberance on its head, is enabled to force its way partly out of the burrow, after which the skin splits cpen and the moth emerges. The empty pupal skin remains for some time projecting from the orifice. (Hig de d-) The presence of this borer in a branch is manifested by an accumulation of chips, matted excrement, and frass, which indi- cates the entrance to the burrow. After a time these holes are closed from within by a silken web, doubtless to protect the con- tained insect from its natural enemies. Smaller twigs wilt and break off, and often the work of the insect is first recognized Fic. 3.—Section of wood show-- only when the severed twigs or branches ing burrow and’ girdling have been brought down in numbers by effect produced by larva of S p) leopard moth. Reduced. high winds. Where the larger larve have Se ee worked just under the bark this splits open the next season, leaving an ugly scar as a reminder of its pernicious operations. (Fig. 4.) NATURAL ENEMIES. No specific natural enemies of the leopard moth other than birds appear to have been recorded in this country, although in Europe three or four wasplke parasites? have been reared. In the explanation of the slow spread of the leopard moth from cities and large towns to the country, allusion has been made to the fact that native birds assist, to some extent at least, in holding 1 An indeterminate chalcidid of the subfamily Encyrtinsee—perhaps (Copidosoma) Lito- mastix truncateilum Dalm.—and Schreineria zeuzerae Ashm., Microgaster sp., and one proctotrypid. THE LEOPARD MOTH. 4 this insect in check in the suburbs. There are the best of reasons for believing that birds like the woodpeckers, which naturally look over the bark and collect all kinds of borers, prey on this spe- cles; even sparrows, it is be- lieved, sometimes destroy the eggs and young larve, as they are known to devour the moths. It is also believed that when the insect succeeds in getting away from the outskirts of cities its enemies increase in number, many in- sectivorous birds aiding in keeping it down. During the day the moths are fed upon by birds and later by bats and night-fly- ing birds. The habit of the larvee of deserting one twig and migrating to a larger one undoubtedly leaves them exposed to the same natural enemies, as this migration has been observed to take place in the daytime as well as after nightfall. It follows that the protection of native birds, especially the wood- peckers and those of related habits, will greatly assist in restraining the undue in- crease and spread of this borer. Squirrels, especially the gray squirrel, which is be- coming common in our large cities, have also been ob- served feasting on the larve, but neither sparrow nor squirrel should be encour- aged because of this habit, since both are responsible for birds. lic. 4.—Work of the leopard moth in branch of maple. About natural size. (Original. ) driving away many of our native 8 FARMERS’ BULLETIN 108. METHODS OF CONTROL. The protected and concealed manner of life of this borer, as shown by the life history, which will apply in the main to borers in general, renders it very difficult of treatment by means of insecticides or other direct measures. The most efficacious remedial measure consists in cutting off and destroying affected branches and in the injection of bisulphid of carbon into the holes or burrows where the larve are at work. PRUNING AND CUTTING BACK. Twigs or branches which, by their wilting or by the presence of burrows showing accumulations of frass or sawdust-like castings at their entrances, indicate the presence of this borer should be care- fully searched out, the smaller ones pruned away and the larger ones eut back, and the amputated portions promptly burned. The stubs should be coated, preferably with grafting wax, to prevent the en- trance of other insects or the spores of decay-producing fungi, although coal-tar preparations containing mineral substances are in somewhat general use for this purpose. After windstorms the affected branches which have fallen to the ground and those which remain attached to the tree should be collected and burned. Wher- ever trees show that they are past recovery it is best to take them out and promptly destroy them. The word “promptly” is used advisedly, since this insect, as previously stated, frequently migrates from one twig or branch to another. INJECTING BISULPHID OF CARBON. In the case of young and rare trees and others which show only a few larval burrows in the bark, bisulphid of carbon is the best remedy and one which has been in general use against the present species in the public parks of New York City. It is injected into the openings of the burrows, and the openings are immediately afterwards closect with various substances. For this injection a mechanic’s long- spouted oil can of small size may be used on large trees, but against a related species the writers have made very good use of a small glass syringe, such as may be purchased at drug stores for about 10 cents. These glass syringes are most serviceable, because the exact amount of bisulphid may be seen when drawn into the syringe and because there is no threading to be injured by the reagent. Metal syringes may also be used, but it is more difficult to measure the exact amount, and the bisulphid acts on the leather packing. Rubber syringes are not serviceable because of rapid corrosion. About a teaspoonful of the liquid bisulphid is sufficient for each burrow. THE LEOPARD MOTH. 9 For stopping the holes after injecting the liquid, putty and moist clay, advised by some, have been found practically useless. Grafting wax, on the other hand, gives perfect satisfaction. Coal tar is less advisable but may be substituted for the latter, or the holes may be closed by inserting a wooden plug and breaking or sawing it off even with the trunk. In any case the stopper should be tight, to exclude water from rains, which might tend to produce decomposi- tion of the surrounding wood or invite the entrance of other insects, like carpenter and other ants and secondary borers, of which there are many species, and injurious fungi. Carbon bisulphid should be handled with the usual precautions against fire, which means that the operator should not smoke while at work. Although the fumes should not be inhaled, as they are poisonous, the liquid will not injure ordinary trees when applied as described and does no harm to the hands. KILLING WITH WIRES. It is possible to reach and destroy many larve by forcing a copper or other pliable wire into the channels. This is a well-known borer remedy. It is impossible, however, by this means to kill the insects in all cases, owing to the length or crookedness of the burrows. Bi- sulphid of carbon should then be used. ATTRACTING TO LIGHTS. To what extent electric or other bright lights are serviceable as an agency in the destruction of the moths of this borer has not been defi- nitely determined, but they possess a certam value. A method fre- quently advised consists in placing shallow pans around electric-light poles in and about parks to attract the moths. The pans are partially filled with water, and a small quantity: of kerosene is poured into them. The moths flying against the globes drop into the pans and are promptly killed when they come in contact with the oil. In this way many males can be destroyed. TREE INSPECTION.1! In large parks the destruction wrought by this borer annually is an important item, and it will be found profitable to establish a system of inspection consisting in the employment of park keepers 1 During the last years of the nineteenth century a long row of beautiful red oaks bor- dering the street between the grounds of the Department of Agriculture and those of the Smithsonian Institution were badly infested by the related carpenter worm (Prionozystus robiniae Forst.). Nearly every tree was infested, and frequently two or three burrows showed near the tops of the trunks. Bisulphid of carbon was applied, as described above, and the holes closed with grafting wax. A year later no insects could be found at work, but wherever this remedy had been applied a small scar remained. Two years later these had entirely disappeared, and the trees looked as if they had never been infested. 10 FARMERS’ BULLETIN 1708. and boys and others who may be engaged at lower wages to keep a constant lookout for evidences of borer attack on valuable trees. In 1893 a New York entomologist spent two months in fighting this insect alone in the city parks of New York, collecting wagonloads of limbs and branches and destroying the contained larvee and pupe. MAINTAINING TREES IN THRIFTY CONDITION. If valuable trees are to be protected, the insect should not be allowed to breed in useless growth. The borers in such trees should be destroyed or the trees promptly felled and burned. Care should be exercised in transplanting trees, and fertilizers should be used in order that the trees may be always thrifty, the better to withstand attack. This also means protection from the attack of aphides, scales and defoliators such as the white-marked tussock moth and the fall webworm, and keeping them free from disease. PROMPT AND THOROUGH TREATMENT ESSENTIAL. Finally, in the control of this species promptness and thorough- ness can not be too strongly emphasized. The bisulphid of carbon remedy should always be used where applicable, and the inspection system advised should be instituted in all public parks and on city streets infested by this pest. Individual owners of valuable trees should become acquainted with the pernicious nature of this borer, and united action should be secured with neighbors whose trees suffer from the ravages of the pest. . PUBLICATIONS OF U. 8S. DEPARTMENT OF AGRICULTURE RELAT- ING TO INSECTS AFFECTING SHADE AND ORNAMENTAL TREES AND HARDY SHRUBS. AVAILABLE FOR FREE DISTRIBUTION. Danger of General Spread of the Gipsy and Brown-tail Moths through Imported Nursery Stock. (Farmers’ Bulletin 453.) The Gipsy Moth and the Brown-tail Moth, with Suggestions for Their Control. (Farmers’ Bulletin 564.) San Jose Scale and Its Control. (Farmers’ Bulletin 650.) The Bagworm, an Injurious Shade-tree Insect. (Farmers’ Bulletin 701.) The Catalpa Sphinx. (Farmers’ Bulletin 705.) Rose-chafer. (Hntomology Circular 11.) The Locust Borer. (Entomology Circular 83.) Euonymus Scale. (Entomology Circular 114.) Oyster-shell Scale and Scurfy Scale. (Entomology Circular 121.) San Jose Seale and Its Control. (Entomology Circular 124.) The Huisache Girdler. (Department Bulletin 184.) Report on the Gipsy Moth Work in New England. (Department Bulletin 204.) Dispersion of Gipsy Moth Lary by the Wind. (Department Bulletin 273.) FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS. Three Insect Enemies of Shade Trees (Elm Leaf-beetle, White-marked Tussock Moth, and Fall Webworm). (Farmers’ Bulletin 99.) Price, 5 cents. The Brown-tail Moth and How to Control it. (Farmers’ Bulletin 264.) Price, 5 cents. The Gipsy Moth and How to Control It. (Farmers’ Bulletin 275.) Price, 5 cents. San Jose Seale, Its Occurrences in United States, with Full Account of its Life History and Remedies to be Used Against It. (Hntomology Bulletin 3, n. s.) Price, 10 cents. The Gipsy Moth in America. (Entomology Bulletin 11, n.s.) Price, 5 cents. Some Insects Injurious to Violet, Rose, and Other Ornamental Plants. (KHn- tomology Bulletin 27, n. s.) Price, 10 cents. Principal Insects Liable to be Distributed on Nursery Stock. (Entomology Bul- letin 34.) Price, 5 cents. Some Insects Injurious to Forests. (Entomology Bulletin 58.) Price, 20 cents. San Jose or Chinese Scale. (Entomology Bulletin 62.) Price, 25 cents. Report on Field Work against the Gipsy Moth and the Brown-tail Moth. (En- tomology Bulletin 87.) Price, 35 cents. The Importation into the United States of the Parasites of the Gipsy Moth and the Brown-tail Moth. (Entomology Bulletin 91.) Price, 65 cents. The Red Spider on Hops in the Sacramento Valley of California. (Entomology Bulletin 117.) Price, 15 cents. The Dispersion of the Gipsy Moth. (Entomology Bulletin 119.) Price, 20 cents. Rose Slug-caterpillar. (Entomology Bulletin 124.) - Price, 5 cents. The Imported Elm Leaf-beetle. (Entomology Circular 8.) Price, 5 cents. 11 eee et ee 12 LIST OF PUBLICATIONS. + rin Pa How to Control the San Jose Scale. (Entomology Circular 42.) Price, 5 cents. The Cottony Maple Scale. (Hntomology Circular 64.) Price, 5 cents. The Catalpa Sphinx. (Entomology Circular 96.) Price, 5 cents. The Bagworm. (Entomology Circular 97.) Price, 5 cents. Common Red Spider. (Hntomology Circular 104.) Price, 5 cents. Rose Slugs. (Hntomology Circular 105.) Price, 5 cents. The Leopard Moth. (Entomology Circular 109.) Price, 5 cents. The Green-striped Maple Worm. (Entomology Circular 110.) Price, 5 cents. The Oak Pruner. (Entomology Circular 130.) Price, 5 cents. Dying Hickory Trees: Cause and Remedy. (Entomology Circular 144.) Price, 5 cents, Flour Paste as Control for Red Spiders and as Spreader for Contact Insecticides. (Entomology Circular 166.) Price, 5 cents. Rose Aphis. (Department Bulletin 90.) Price, 5 cents. Food Plants of the Gipsy Moth in America. (Department Bulletin 250.) Price, 10 cents. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1916 DIV.INSECTS UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS BULLETIN Wasurnaton, D.C. T2l1 Aprit 28, 1916 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE ROSE-CHAFER:' A DESTRUCTIVE GARDEN AND VINEYARD PEST. By F. H. Currrenven, In Charge of Truck-Crop and Stored-Product Insect Investigations, and A. L. QUAINTANCE, In Charge of Deciduous Fruit Insect Investigations. CONTENTS. Page. Page. Mntroductonyee kee cae eee neces oa 1 | Methods of control—Continued. DIsimibUblone- Yah os- caer este Sey eesiats 1 Use of arsenicals on grapes and other fruits 7 Food plants and injury-.--. 2 andipickine ssa... = eee = Seek 7 Natural history and habits . 55 4 Netting and! bagging 52.22. .2..... aes. a Methods of control... ..2....--...-- ae 5 Wserotiure; plants eee — seas sees se 8 Practically useless applications........-- 6 Destroying the larve and pup®...-.-.---. 8 Use of arsenicals on roses.....--..-..---- 6: |) Generaliconsiderations. .....- 2-2. -22--5--+-- 8 INTRODUCTORY. About the time of the blossoming of grapes, roses, and many garden flowers a long-legged beetle of a light ocher or yel- lowish-brown, color, called the rose-chafer or “ rose-bug,” makes its appearance in certain sections of the country and strips bushes and vines of blossoms and foliage. This beetle 1s about one-third of an inch in length and may be recognized by comparison with the accom- panying illustration (fig. 1, a). These insects appear suddenly and in vast swarms in certain years, usually toward the middle of June in the Northern States and about two weeks earlier in their southern range, and overrun the garden, vineyard, orchard, and nursery. In about a month or six weeks from the time of their first arrival, generally after they have done a vast amount of damage, the beetles disappear as suddenly as they came. DISTRIBUTION. The rose-chafer occurs in the North,. from Canada and Maine southward to Virginia and Tennessee, and westward to Oklahoma and Colorado. It is particularly injurious in Massachusetts, Rhode ’ 1Macrodactylus subspinosus Fab. ; order Coleoptera, family Scarabaeidae. 28072°—Bull. 721—16 2 FARMERS’ BULLETIN Tai; Island, New Jersey, Delaware, and Ohio, and has been reported as very destructive in portions of New York, Pennsylvania, Maryland, Virginia, West Virginia, Ilinois, Indiana, Kansas, Nebraska, south- ern Michigan, and Vermont, but is not destructive in all portions of these States. Light sandy regions are greatly preferred by the in- sects as breeding grounds, and clay lands, unless near sandy soil, are seldom troubled with them. FOOD PLANTS AND INJURY. For some time after the rose-chafer was first noticed it confined its ravages to the blossoms of the rose. There is a record, however, of its having been destructive to grapes as early as 1810. In later years it has extended its range of food plants until now it is nearly Fic. 1.—The rose-chafer (Macrodactylus subspinosus): a, Adult. or beetle; 0b, larva; ec, d, mouthparts of larva; e, pupa; f, injury to leaves and blossoms of grape, with beetles at work. a, b, e, Much enlarged; c, d, more enlarged; f, slightly reduced. (From Marlatt.) omnivorous. The rose and grapevine especially suffer from its depre- dations, but it is almost equally destructive to fruit, shade, and other trees and shrubs. In times of great abundance these insects com- pletely destroy flowers and other ornamental plants of many sorts, even attacking berries, peas, beans, and nearly all garden fruits and vegetables, corn, wheat, and grasses. Almost every form of vegeta- tion is devoured. The beetles do not confine their ravages to any particular portion of a plant, but consume alike blossoms, leaves, and fruit. In their attack upon the grape they first devour the blossoms, then the leaves, which they completely strip, leaving only a thin network, and later the young berries are eaten (figs. 2 and 3). Whole vine- THE RCSE-CHAFER. 8 yards and orchards are often devastated, and the fruit crop of certain sections of country destroyed. It is no uncommon sight to see every young apple on a tree completely covered and obscured from view by a sprawling, struggling mass of beetles. (See fig. 4.) Since the late eighties the rose-chafer has been particularly injuri- ous in grape-growing regions and has been the subject of research and experiment at the New Jersey Agricultural Experiment Station and by the Bureau of Entomology in the Lake Erie region of Pennsylvania.? Fic. 2.—Grape foliage showing injury by rose-chafer. (Original.) ROSE-CHAFER POISONOUS TO CHICKENS. It has frequently been stated that the rose-chafer is injurious to small chickens, and it was the general belief that their death was due to mechanical injury or puncturing of the lining of the digestive tract by the spines on the legs of the beetles that had been swallowed. In other cases it was stated that the rose-chafer had eaten into the crops of the chicks. Cases have been reported recently of hundreds of chickens being killed in this manner. Death usually occurred in from 9 to 24 hours after feeding. Some experiments have been per- formed to determine the cause of the injury, and it was proved that 1 Johnson, Fred. Vineyard spraying experiments against the rose-chafer in the Lake Erie Valley. U.S. Dept. Agr. Bur. Ent. Bul. 97, pt. 3, p. 53-64, pl. 4-7, fig. 16-21. 1911. 4 FARMERS’ BULLETIN 1721. 15 to 20 rose-chafers were sufficient to cause the death of a chick 1 week old. In the case of a 10-week-old chicken, 96 undigested rose- chafers were counted in a post-mortem examination. An extract made from 40 grams of rose-chafers was injected into rabbits, which died in six minutes, and in one case in three and one-fourth minutes after the injection of 4c. c. Other rabbits were killed in proportion Fic, 5.—Grape cluster showing almost total destruction of young berries through feeding of rose-chafer. (From Johnson.) to the size and dose. The opinion was reached that owing to the fact that the insect feeds on a large number of plants, and especially on daisies, its body contains a neuro-toxin which affects the hearts of small animals, such as chickens and rabbits. NATURAL HISTORY AND HABITS. The rose-chafer, as already stated, appears early in June, the date varying somewhat according to locality and season. Soon after 1 Lamson, G. H. The poisonous effects of the rose-chafer upon chickens. Jn Science, v. 43, no. 1100, p. 188-139. Jan. 28, 1916. THE ROSE-CHAFER. 5 emerging from the ground it mates and begins feeding. For from four to six weeks after their appearance the beetles continue feeding, almost constantly paired. The female deposits her eggs singly, from 24 to 36 in number, a few inches beneath the surface of the earth, where in from two to three weeks they hatch and the young larve or grubs begin feeding on such tender rootlets, preferably of grass, as are in reach. By autumn the larve, which are yellowish white in color, with pale-brown heads, have reached full growth and present the appearance shown in figure 1 at 6. Late in autumn they descend Ic; 4.—Young apple showing injury by rose-chafer. (Original.) lower into the earth, below the frost line, each grub forming a little earthen cell in which it passes the winter. In April or early in May they transform to pup, and in from two to four weeks afterwards the beetles emerge, dig their way out of the ground, and renew their destructive work. } Sia sireur Sh) ei altel 5, beetles not coming from the ground a, Adult beetle; 5, larva. Enlarged. uni ihe fourth isprings) Thus: the)“: Cuter siiusteation.) wireworms, as such, are in the ground during the growing season ‘of three years. The beetles of the inflated wireworm have been observed in large numbers on the blossoms of wild rosebushes, where they were apparently eating the petals. The beetles of the dry-land wireworm are a little later in coming out of the ground, emerging in June and July. In the dry-land regions this wireworm feeds only during the spring, burrowing down from 4 to 8 inches below the surface to pass the hot, dry months. 8 FARMERS’ BULLETIN 1725. REMEDIAL MEASURES. As will be seen from the life history, the generations about to become adults are inactive wireworms from June to August, trans- forming to beetles in the early part of August. The resting and transforming wireworms usually are found at a depth of 4 to 8 inches, and any disturbance of the soil to such depth at this time will destroy them. The ground is very hot during this period of the year, and the air extremely dry, so that even the resting wireworms that are not actually crushed by the cultivation soon succumb to drying . when their cells are broken open. The usual farm practice in the Fig. 5.—The dry-land wireworm: a, Adult; 6, larva;c, under surface of head of larva; d, side of last segment of larva. a, 6, Enlarged; c, d, more enlarged. (Author’s illustration.) dry-land farming region of the Northwest where these wireworms are most troublesome may be roughly outlined as follows: Immediately after seeding the wheat in early spring the summer fal- low land is plowed to a depth of from 4 to 7 inches. This usually is done in April, but if horses and help can be spared from seeding, the summer fallow is plowed as early in the spring as the land can be worked. The next operation on-the fallow land is disking the land ° in June or early July to maintain the dust mulch and kill the weeds and volunteer wheat. Some of the more progressive farmers now practice fall plowing of the stubble and disking the fallow land only in the spring. The field is disk-harrowed early in the spring if the land has run together during the winter and is caked, otherwise the land is harrowed with a drag or spring-tooth harrow. It is then WIREWORMS DESTRUCTIVE TO CEREAL AND FORAGE CROPS. 9 seeded and dragged and receives no further treatment until harvest. The seeder usually is set to sow at a depth of about 3 inches, although, if the moisture content is high enough, 1 inch is considered sufficient. Wheat hay is used extensively in this country, and is cut while the wheat is in the dough stage, which usually is from July 4 to July 15. The wheat crop is harvested from August 1 to September 15. In order to destroy wireworms this practice should be altered in the following manner: (1) Disk or drag-harrow the summer fallow as early as possible in the spring in order to produce a dust mulch and thereby conserve the accumulated winter moisture. (2) Continue the disking as often as is necessary in order to maintain the dust mulch and keep down the Fig. 6.—A horned toad, an enemy of the western Wireworms. (Author’s illustration. ) weeds. (3) Plow the summer fallow in July or early in August and immediately drag. (4) Plow the stubble as soon as the crop is -removed. | As these wireworms are of three different ages in most infested fields, and as only about one-third of these are in the pupal stage, changing to beetles each year, it is evident that the first year of this practice will not show marked results. However, if the practice is continued for two years it will reduce the number of these pests very considerably. Aside from its beneficial results in killing insects, this method of handling the land will materially reduce the weeds, the early disking merely softening up the soil and allowing all the weed seeds present to sprout, the entire crop of weeds subsequently being _ destroyed by the summer plowing. By the present method of farm- ing, the weed seeds are turned down to such a depth that many can not germinate; but they lie dormant, and sprout whenever they happen 10 FARMERS’ BULLETIN 725. to be brought to the surface by subsequent cultivation. One crop of weed seed is in this manner often a pest for several succeeding years. NATURAL ENEMIES OF WIREWORMS. Most of our common song birds feed rather extensively upon both the beetles and the wireworms themselves, and any regulation designed to protect these birds and encourage their increase will undoubtedly be effective in reducing the number of these pests. In the desert regions of the West thé small lizards, commonly called sand toads or horned toads (fig. 6), feed very extensively upon wire- worms and their beetles and should be protected by the farmers of these regions. The examination of the stomachs of a large series of field frogs collected on the shores of Lake Oneida, in upper New York, proves beyond a doubt that these frogs are of enormous value in destroying the beetles of the wheat wireworm when these beetles are laying their eggs in the grasslands. These frogs are slaughtered in enormous numbers every year for the summer hotel trade. Any regu- lation which would put a stop to this practice would be of great value to the agricultural interests of this and similar sections. _Wireworms are not severely attacked by parasites, so far as is known. How- ever, several parasites are being studied with the object of using them as a means of controllmg wireworms. The introduction of several known fungous diseases also is being studied. USELESS REMEDIAL MEASURES. The use of various substances upon the seed corn and wheat has proven of little value in fighting wireworms. The application of certain commercial fertilizers recommended as insecticides is also of but little use. The application of lime is not effective as an insecti- cide, but is of value in rendering the soil more easily drained. Late fall plowing has probably been the most universally recommended method of combating these insects. However, at least for the kinds of wireworms on which this method has been tried, it is quite useless. Trapping the larve with baits of poisoned vegetables may be of some value under intensive methods of farming, but it is impracticable in the growing of field crops. PUBLICATIONS OF U.S. DEPARTMENT OF AGRICULTURE RELATING TO INSECTS INJURIOUS TO CEREAL AND FORAGE CROPS. AVAILABLE FOR FREE DISTRIBUTION. Cotton Bollworm, Summary of Its Life History and Habits. (Farmers’ Bulletin 290.) Common White Grubs. (Farmers’ Bulletin 543.) The Larger Corn Stalk-borer. (Farmers’ Bulletin 634.) The Chalcis-fly in Alfalfa Seed. (Farmers’ Bulletin 636.) The Grasshopper Problem and Alfalfa Culture. (Farmers’ Bulletin 637.) The Hessian Fly. (Farmers’ Bulletin 640.) Alfalfa Attacked by the Clover-root Curculio. (Farmers’ Bulletin 649.) The Chinch Bug. (Farmers’ Bulletin 657.) The Hessian Fly Situation in 1915. (Office of the Secretary Circular 51.) The Spring Grain Aphis or ‘“‘Green Bug”’ in the Southwest and the Possibilities of an Outbreak in 1916. (Office of the Secretary Circular 55.) Southern Corn Rootworm, or Budworm. (Department Bulletin 5.) Western Corn Rootworm. (Department Bulletin 8.) The Oat Aphis. (Department Bulletin 112.) The Alfalfa Caterpillar. (Department Bulletin 124.) Wireworms Attacking Cereal and Forage Crops. (Department Bulletin 156.) The Sharp-headed Grain Leafhopper. (Department Bulletin 254.) Hessian Fly, (Entomology Circular 12.) Two Destructive Texas Ants. (Entomology Circular 148.) Clover Mite. (Entomology Circular 158.) Slender Seed-Corn Ground-beetle. (Entomology Bulletin 85, pt. IT.) Clover-root Curculio. (Entomology Bulletin 85, pt. III.) Contributions to Knowledge of Corn Root-aphis. (Entomology Bulletin 85, pt. VI.) Maize Billbug. (Entomology Bulletin 95, pt. II.) So-called ‘Curlew Bug.’? (Entomology Bulletin 95, pt. IV.) FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS. The Southern Corn Leaf-Beetle. (Department Bulletin 221.) Price, 5 cents. The Pea Aphis with Relation to Forage Crops. (Department Bulletin 276.) Price, 15 cents. The Grasshopper Problem in New Mexico During the Summer of 1913. (Department Bulletin 293.) Price, 5 cents. Army Worm. (Entomology Circular 4.) Price, 5 cents. Larger Corn Stalk-borer. (Entomology Circular 16.) Price, 5 cents. _ Clover Mite. (Entomology Circular 19.) Price, 5 cents. Joint-worm. (Entomology Circular 66.) Price, 5 cents. Some Insects Affecting Production of Red Clover Seed. (Entomology Circular 69.) Price, 5 cents. Hessian Fly. (Entomology Circular 70.) Price, 5 cents. Slender Seed-corn Ground-beetle. (Entomology Circular 78.) Price, 5 cents. Grasshopper Problem and Alfalfa Culture. (Entomology Circular 84.) Price, 5 cents. Spring Grain-Aphis. (Entomology Circular 85.) Price, 5 cents. Corn Leaf-aphis and Corn Root-aphis. (Entomology Circular 86.) Price, 5 cents. Spring Grain-aphis or So-called ‘“Green Bug.’’ (Entomology Circular 93.) Price, 5 cents. Wheat Strawworm. (Entomology Circular 106.) Price, 5 cents. Chinch Bug. (Entomology Circular 113.) Price, 5 cents. Larger Corn Stalk-borer. (Entomology Circular 116.) Price, 5 cents. Western Grass-stem Sawfly. (Entomology Circular 117.) Price, 5 cents. Clover Root-borer. (Entomology Circular 119.) Price, 5 cents. Alfalfa Caterpillar. (Entomology Circular 133.) Price, 5 cents. Alfalfa Weevil. (Entomology Circular 137.) Price, 5 cents. Alfalia Gall Midge. (Entomology Circular 147.) Price, 5 cents. Two Destructive Texas Ants. (Entomology Circular 148.) Price, 5 cents. 11 f2 FARMERS’ BULLETIN 1725. Fall Army Worm and Variegated Cutworm. (Entomology Bulletin 29.) Price, 5 cents. Some Insects Attacking Stems of Growing Wheat, Rye, Barley, and Oats, with Meth- ods of Prevention and Suppression. (Entomology Bulletin 42.) Price, 5 cents. Mexican Conchuela in Western Texas in 1905. (Entomology Bulletin 64, Pt. I.) Price, 5 cents. New Breeding Records of Coffee-bean Weevil. (Entomology Bulletin 64, Pt. VII.) Price, 5 cents. Notes on Colorado Ant. (Entomology Bulletin 64, Pt. IX.) Price, 5 cents. Chinch Bug. (Entomology Bulletin 69.) Price, 15 cents. Papers on Cereal and Forage Insects. (Entomology Bulletin 85, 8 pts.) Price, 30 cents. Lesser Clover-leaf Weevil. (Entomology Bulletin 85, Pt. I.) Price, 5 cents. Sorghum Midge. (Entomology Bulletin 85, Pt. IV.) Price, 10 cents. New Mexico Range Caterpillar. (Entomology Bulletin 85, Pt. V.) Price, 10 cents. Smoky Crane-fly. (Entomology Bulletin 85, Pt. VII.) Price, 5 cents. Cowpea Curculio. (Entomology Bulletin 85, Pt. VIII.) Price, 5 cents. Timothy Stem-borer, New Timothy Insect. (Entomology Bulletin 95, Pt. I.) Price, 5 cents. Chinch-bug Investigations West of Mississippi River. (Entomology Bulletin 95, Pt. III.) Price, 10 cents. False Wireworms of Pacific Northwest. (Entomology Bulletin 95, Pt. V.) Price, 5 cents. Legume Pod Moth and Legume Pod Maggot. (Entomology Bulletin 95, Pt. VI.) Price, 5 cents. Alfalfa Looper. (Entomology Bulletin 95, Pt. VII.) Price, 5 cents. Results of Artificial Use of White-fungus Disease in Kansas, with Notes on Approved Methods of Fighting Chinch-bugs. (Entomology Bulletin 107.) Price, 10 cents. Leathoppers Affecting Cereals, Grasses, and Forage Crops. (Entomology Bulletin 108.) Price, 20 cents. Spring Grain-aphis or Green Bug. (Entomology Bulletin 110.) Price, 25 cents. Preliminary Report on Alfalfa Weevil. (Entomology Bulletin 112.) Price, 15 cents. Principal Cactus Insects of United States. (Entomology Bulletin 113.) Price, 15 cents. Cotton Bollworm, Account of Insect, with Results of Experiments in 1903. (Farmers’ Bulletin 191.) Price, 5 cents. Cotton Bollworm, Some Observations and Results of Field Experiments in 1904. (Farmers’ Bulletin 212.) Price, 5 cents. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1916 DIV.INSECTS UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS’ BULLETIN WasuineTon, D. C. ress | May 23, 1916 Contribution from the Bureau of Entemology, L. O. Howard, Chief. THE TRUE ARMY WORM' AND ITS CONTROL. By W. R. Watton, Entomological Assistant, Cereal and Iorage Insect Investigations. INTRODUCTION. This publication is designed to convey to the farmer, in a brief and simple manner, the natural history of the true army worm, a caterpil- ic. 1.—The true army worm: Full-grown larva or eaterpillar. Enlarged. (Original. ) lar which from time to time becomes enormously destructive to grow- ing cereals, and sometimes to forage crops; to give him a summary of the information necessary for its control; and especially to urge upon him the necessity for constant vigilance in the combat with this insect. The true army worm (fig. 1) is often confused in the public mind with the fall army worm,’ “ overflow worm,” or “ grass worm” as 1 (Heliophila) Oirphis unipuncta Haw. ; order Lepidoptera, family Noctuidae. 2 Laphygma frugiperda S§. & A, Notr.—This bulletin is of general interest to crop growers everywhere, and especially east of the Rocky Mountains. 34940°—Bull. 731—16 9 FARMERS’ BULLETIN 131. it is known in some of the extreme Southern States. The latter in- sect always originates in the South and travels northward as the summer advances. The western army cutworm? also is occasionally mistaken for the true army worm, but it occurs in destructive abun- dance only throughout the regions west of the Mississippi River. Both of the latter insects will be treated in a separate publication. GENERAL DESCRIPTION. The fully developed parent of the army worm (figs. 2, a@,and 5) isa moth or “miller” measuring about 14 inches across the expanded wings. It is brownish-gray in color, having a single small white spot near the center of the front pair of wings, the hind wings being somewhat darker along the hind edges. Although these parents of the worm sometimes are very numerous, they fly only at mght and are therefore often entirely overlooked by the farmer. The stage of the insect most familiar to him is the full-grown, striped, nearly naked caterpillar (figs. 1 and 2, >), usually discovered in the act of devour- ing his crops and in most cases after having already destroyed the greater portion of the infested crop. WHERE THE ARMY WORM OCCURS. The true army worm is probably a native of North America, although it is also found in South America. It occurs throughout most of the United States east of the Rocky Mountains, including the States bordering the western banks of the Mississippi and the Missouri Rivers. It also has been found in New Mexico, Arizona, and California. It is not known from the Rocky Mountain Plateau region. (See fig. 3.) ECONOMIC IMPORTANCE AND MANNER OF INJURY. The loss in money to the farmer by army worms in the past has been exceedingly great, and although no exact estimate is possible, it is safe to say that in the Eastern States alone many millions of dollars’ worth of grain and forage crops have disappeared down their throats during the past 30 years. 1 (Chorizagrotis) Euxoa auciliaris Grote. . THE TRUE ARMY WORM AND ITS CONTROL. 33 re. 2: Stages and work of the true army worm and some of its insect enemies: a, Parent or moth; b, full-grown larva; c, eggs; d, pupa in soil: e, parasitic fly, Winthemia quadripustulata, laying its eggs on an army worm; f, a ground beetle, Calosoma calidum, preying upon an army worm, and, at right, Calosoma larva emerging from burrow; g, a digger wasp, Sphex sp., carrying an army worm to its burrow ; h, Hnicospilus purgatus, a wasplike parasite of the army worm. All about natural size. (Original.) rs Hews FARMERS’ BULLETIN 131, The army worm injures crops in but one way, and that is by eating away all the tender portions of the leaves, the immature seed, and sprouts, and when numerous it may even devour the plants down to the very ground. The more important and by far the most con- spicuous injury is always inflicted by the nearly full-grown cater- pillar, whose greed and capacity for food are almost unbelievable. The pupa takes no food. The moth subsists principally upon the nectar gathered from flowers. FOOD PLANTS. The army worm feeds by preference upon grasses, both wild and cultivated; next, upon the grasslike grains, such as the several varie- Fic. 3.—Map showing localities in the United States in which the true army worm has been destructive. (Original.) ties of millet, which suffer severely during outbreaks of the insect. Wheat in its unripe stages, corn, oats, and rye seem to be preferred in the order named. In some portions of the country alfalfa also suffers injury; apparently damage to this crop occurs only in the Southwestern States—Texas, Oklahoma, New Mexico, and Arizona. Occasionally clover is attacked, but such occurrences are rare. WHERE INVASIONS OF THE ARMY WORM COME FROM. The true army worm usually appears in the fields very suddenly, and it seems quite certain that the moths at times fly in great num- bers for many miles, in the direction of the prevailing winds, and alight in a body to deposit their eggs at some place favorable to the development of their offspring. This fact accounts for the sudden THE TRUE ARMY WORM AND ITS CONTROL. . 5 appearance of the army worm in regions far removed from any known source of infestation. The moth, however, seems to be present in small numbers, over most of the area in which it occurs, during a portion of every year, but this fact does not account for the sudden great invasions which occur from time to time. WHEN INVASIONS MAY BE EXPECTED. Generally speaking, outbreaks of the true army worm are more common following cold, backward springs and should be looked for first in neglected portions of fields upon which rank growths of wild grasses or lodged and fallen unripe grain are to be found. These should be examined frequently and closely, especially during late April, May, June, and early July, in order to discover the small greenish caterpillars, which may be found in great numbers feeding near the surface of the ground under the sheltering, overhanging leaf blades. LIFE HISTORY. The army worm, like many other common insect pests, has four forms or stages, as follows: First, the parent moths or millers, which seek out rankly growing grass or grasslike grains, such as millet, upon which they lay their eggs (fig. 2, ¢). From these eggs hatch the little caterpillars or ‘“ worms,” which feed and grow rapidly. When full grown they shed their skins and change to the brown pupa or resting stage, usually beneath the surface of the soil. From these pup come the parent moths, which in turn mate and lay their eggs, thus providing for another brood of caterpillars. There are usually three generations of caterpillars in any one year, but seldom or never two successive outbreaks in any given locality. THE EGG STAGE. The eggs are laid by the parent moths at night, usually in the folded blades or under the leaf sheaths of grains and grasses (fig.2,¢). These resemble small white beads, each considerably smaller than the head of a common pin, and are deposited in masses or rows on the plants selected. Moist or shaded spots usually are chosen for this purpose by the moths, many of which seem to congregate and lay their eggs in the same locality. These eggs hatch in from 8 to 10 days and from them come the very small greenish caterpillars er “ worms.” THE CATERPILLAR OR LARVAL STAGE. When the caterpillars are first hatched they are very tiny and, although countless thousands of them may be present, they consume, 6 FARMERS’ BULLETIN 131. at this time, comparatively little food. Feeding near the ground, sheltered from view by the overhanging grain or grasses, they almost invariably escape the notice of the farmer. If the colony of worms can be discovered at this stage of their growth the infestation usually can be stamped out completely by prompt and vigorous measures, such as spraying with arsenicals or covering with straw and burn- ing over the infested spot. As the young worms grow and feed, their skins become too small for them, so presently they split and are shed, and the caterpillars begin feeding more greedily than ever. This occurs several times during the life of the caterpillar, until the worm becomes full grown. The time required for full growth is from 3 to + weeks. The full- grown army worm (figs. 1 and 2, >) is a nearly naked, smooth, striped caterpillar, about 14 inches long. Its general color is usually green- ish, and the stripes, one along each side and a broad one down the center of the back, are dark and often nearly black. The stripe along the back usually has a fine, light-colored, broken stripe running down its center. The color of the body between the dark stripes varies from greenish to reddish brown. The head is greenish brown speckled with black. When an army of these worms is at work in a field the champing of their jaws is plainly to be heard, as they greedily devour every blade in sight. In this stage the army worm frequently consumes all of the food supply near the place where it has developed from the egg. When such is the case the caterpillars mass together and crawl away in a body in search of other food. It is this habit which has gained for the insect the popular name of “army worm.” The massing to- gether of the worms affords the farmer an opportunity of destroying them in great quantities by mechanical methods described on a fol- lowing page of this publication. When the full-grown caterpillars cease feeding they usually burrow into the soil to the depth of a few inches and by dint of twisting and turning form a cavity or cell therein. The worm then begins to shrink and shorten, after which the skin splits and is shed and the pupa appears beneath it. When the worms are very numerous many of them pupate on the surface of the ground, hidden under clods, boards, or bunches of dried grass and fallen grain. THE PUPA OR RESTING STAGE. The pupa (figs. 2, 7, and 4) or resting stage of the true army worm resembles a date seed in size and shape, but is more pointed at one end. In color it is at first a reddish or chestnut brown, becoming almost black as the time for emergence of the moth approaches. Its THE TRUE ARMY WORM AND ITS CONTROL. : 4. skin or covering is smooth and tough, and the pupa is unable to move any portion of its body excepting its tail, which it wriggles vigorously upon being disturbed. If the soil in which the pupz are resting be lightly cultivated during this time and the pupe thrown to the sur- face, most of them will be killed by exposure to the weather, crushed by the cultivating implements, or eaten during the day by birds or at night by skunks which roam the fields and consume great quantities of such food. THE PARENT OR MOTH STAGE. When the moth (figs. 2, @ and 5) crawls forth from the pupal case it has not yet developed its wings, which are crumpled and folded in pad- like masses on each side of its back. It usually crawls up the stem of some plant and begins to expand its wings, waving them back and forth slowly for about an hour, by which time they are completely developed and the insect is capa- ble of flying. However, if undisturbed, the 5, 4 ne true Sane moths will usually remain at rest for several worm: Pupa. En- hours before flying away to mate and lay their “78% (O™isinal.) egos. It takes from 7 to 8 weeks for the insect to develop from the egg to the adult or moth. After the moths have expanded their wings they do not grow any larger; the-small moths are not the young of larger moths, but the os ih ‘A ( ut Nn W “| Tic. 5._—The true army worm: Parent or moth. Enlarged. (Original.) male moth or parent of the army worm is usually considerably smaller than the female. The army worm moth is strongly attracted to lights at night and frequently swarms of these moths are seen about lights out of doors shortly before an outbreak of the army worm. Farmers would 8 FARMERS’ BULLETIN 131. therefore do well to learn to recognize the moth at sight, as in this way they could be warned of the probable subsequent injurious abundance of the caterpillar. The moths may readily be known by their plain brownish-gray appearance and the presence of a single very small, almost pure white speck or spot near the center of each of the front wings (see figs. 2,@and 5). The moths seldom or never lay their eggs near the spot where they have developed and fre- quently fly for many miles before doing so. Thus there are seldom two successive outbreaks during the year in any given locality. It is not yet definitely known where or how the army worm lives over the winter, but the indica- tions are that it does so in the partially grown cater- pillar stage. HISTORY OF THE ARMY WORM IN THE UNITED STATES. The army worm has been known as a serious pest on cereal and forage crops in the United States since early colonial times. As early as the year 1632 it is recorded as injuring corn in New England by Peter Kalm, a Swedish naturalist who traveled in this country. In Fic. 6.—Winthemia quadripustulata, a fly parasitic the aS 143 a great out- on the true army worm: Adult. Much enlarged. break of the army worm 1s (Omen) recorded as having occurred throughout that portion of the country now known as the North Atlantic States. From then down to the present time the insect has hampered agriculture and robbed the farmer mercilessly at compara- tively short but irregular intervals of time. The most recent serious invasion occurred during the summer of 1914, at which time the entire agricultural region east of the Rocky Mountains and north of the Gulf States suffered to a greater or less degree. From the past history of the insect the farmer may confidently expect to be com- pelled to cope with it from time to time, and he should ever be on the alert during the spring and early summer months in order to dis-: cover the pest before it has made serious inroads upon his crops. / THE TRUE ARMY WORM AND ITS CONTROL. 9 NATURAL ENEMIES. Most fortunately for the farmer, the army worm has many natu- ral enemies among the native insects, reptiles, birds, and mammals. INSECT ENEMIES. One of the commonest and most effective of its insect foes is a medium-sized gray fly! (fig. 6), closely resembling, and _ slightly larger than, the house fly. This parasite sticks its eggs fast to the skin of the caterpillar (fig. 2, b and e) and the quickly hatching maggots bore through the skin into the flesh, where they soon devour the entire inside por- tions of the army worm’s body. These flies multiply rapidly and often become so numerous as to control the army worm completely in a given locality. Another common insect foe is a very small wasplike creature (fig. 7),? which pierces the caterpillar with its sting or ovipositor, laying its eggs inside the army worm’s body, where they quickly hatch and, the maggots having eaten their fill, bore their way outward and ee ee dt eceaey oea ot spin little silken cocoons in a mass to- the wasplike parasite Apanteles gether, somewhat resembling grains of Dee aor es i rice entangled in a mass of cotton. This ‘parasite is also sometimes numerous enough to be of great service in controlling the pest. _ Several other insect enemies serve more or less efficiently in combating the army worm. Some of these are shown in figure 2, ig, he fod Wie. 7. WILD BIRDS AND OTHER ENEMIES. According to the records of the United States Biological Survey, more than 40 species of native wild birds are known to eat the army worm in its various stages. Among the most important of these are the following: Crow blackbird or grackle, yellow-headed blackbird, chipping sparrow, bluebird, prairie hen, and European starling. Domestic fowls of all kinds will greedily devour the caterpillars and pupe if allowed to roam over infested fields. Skunks and toads also undoubtedly eat thousands of the army worms, both caterpillars and 1 Winthemia quadripustulata Fab. 2 Apanteles militaris Say. 8 Calosoma Calidum Fab., (Ammophila) Sphex sp., and Enicospilus purgatus Say. 10 FARMERS’ BULLETIN 1731, pupe. These birds and other animals should therefore be encour- aged and protected by the farmer by all possible means. CONTROL MEASURES. WATCHFULNESS AS A FACTOR. The importance of watchfulness, on the part of the farmer, as a factor in combating the army worm can not be too greatly empha- sized. Upon the discovery of the pest in its younger stages depends very largely the possibility of stamping out an infestation before serious injury to crops has occurred. The farmer should examine his meadows frequently during the spring and early summer months, particularly those planted to timothy, bluegrass, and especially mil- let. He should not be satisfied with looking merely at the surface of the stand; the thicker and longer the growth, the greater the danger from the army worm. The grass or grain should be parted with the hands in various parts of the field and the lower portions of the growth closely examined, in order to discover the presence of the small, greenish caterpillars, and if such be found in any number the area covered by the infestation should be determined and vigorous action taken at once to destroy the worms before they become large enough to begin their journey to other portions of the farm. If the infested spot be small, the grass or grain can be mowed off and straw scattered over the spot and burned, thus destroying the worms. If the caterpillars have become distributed over a considerable area, this can be marked off by stakes and the crop sprayed heavily with a mixture of Paris green at the rate of 1 pound to 50 gallons of water. In case this poison is used, care should be exercised in preventing stock from gaining access to the poisoned grass or grain and being injured or killed by eating it. It is far better to sacrifice a portion of the crop, if the destruction of the pest can be accomplished thereby, because if the army worms are not destroyed they will take the crop anyway and probably devastate other portions of the farm. POISONED BAITS. Poisoned baits of varying composition have long been used as a means of destroying the many different species of cutworms and also the army worm. An efficient bait of this kind may be pre- pared and used as follows: To 50 pounds of wheat bran and 1 pound of Paris green or 2 pounds of arsenate of lead add the juice of one-half dozen oranges or lemons. Then bring the mass to a stiff dough by adding low-grade molasses or sirup, preferably the former, and scatter the mixture broadcast in small pieces throughout the infested field. This poisoned bait may be safely used in alfalfa THE TRUE ARMY WORM AND ITS CONTROL. 11 and cornfields where it is desired, if possible, to save the crop for forage purposes. _ MECHANICAL MEASURES. In case the worms are not discovered until they have begun to travel in a mass, they can usually be destroyed by furrowing or ditching (fig. 8) completely around the infested area. In attempt- ing to cross such ditches the worms will fall into them and can easily be destroyed by crushing them with a log dragged back and forth through the ditch or furrow. If shallow post holes are sunk in the bottom of the ditch at intervals of about 20 feet, the worms will crawl along the ditch bottoms and fall into the holes, where Fic. 8.—Ditch prepared to entrap marching army worms. A log, dragged back and forth through the ditch, crushes the worms which have falled into it. (Original.) they may be destroyed by crushing or other means. If the subsoil be of such a nature that water penetrates it but slowly, the post holes may be partially filled with water, on the top of which a layer of coal oil or petroleum may be poured. Upon falling into such holes, the worms are almost immediately destroyed without further action on the part of the farmer. SUMMARY OF CONTROL MEASURES. (1) Watch fields of growing grass and grain carefully, especially the meadows, during the spring and early summer months, in order 12 FARMERS’ BULLETIN 131. to discover the army worms before they have a chance to become full grown and spread over the entire farm. When the worms are discovered at work do not lose a minute, but attack them vigorously by means of the measures outlined in the foregoing pages. (2) In case the worms are crawling in a body, surround them with _ a furrow or ditch and crush them with a log drag as they fall into it. . (3) Poison them by spraying crops not intended for forage pur- poses with 1 pound of Paris green to 50 gallons of water, or with 2 pounds of arsenate of lead to 50 gallons of water. In case the Paris green is used on tender plants, like corn, 2 pounds of freshly slaked lime should be added to 50 gallons of the mixture. This is to prevent burning the tender plants. Where spraying is not practicable, the use of the poisoned bran bait, mentioned on page 10 of this publication, is strongly recommended. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1916 UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS’ BULLETIN Wasuincton, D. C. Poe JUNE 9, 1916 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE CORN AND COTTON WIREWORM 1! IN ITS RELATION TO CEREAL AND FORAGE CROPS, WITH CONTROL MEASURES. By Epmunp H. GIBSON, Scientific Assistant, Cereal and Forage Insect Investigations. INTRODUCTION. During the three years which have elapsed since the investigation of the corn and cotton wireworm (fig. 1, 6) was begun there have been constant requests by farmers and others for remedial measures, and it is in answer to and underground stems these requests that the : of plants which are present paper has been thereby weakened and prepared. The injury, stunted or killed. as in the case with other “wireworms, is caused by the feeding of the worm- like young or larve of slender beetles, known as “click beetles” or “snapping beetles,” upon the roots, sprouts, EXTENT OF DAMAGE BY THE CORN AND COTTON WIREWORM. These wireworms have been known totally to destroy corn through- out fields of large acre- Fic. 1.—The corn and cotton wireworm: a, Adult, or beetle; b, larva, or wireworm. Much enlarged. (Hyslop.) age. However, this is not usually the case and the attack is most frequently concentrated in “spots” scattered throughout the field, the plants in these spots being wholly destroyed. In other parts of the field there may be slight injury as shown by the dwarfed ap- 1 Horistonotus uhleri Horn; order Coleoptera, family Elateridae. Norr.—The object of this bulletin is to set forth in a popular form what is known of the habits of the destructive corn and cotton wireworm, in order that farmers and planters may more effectively carry out control measures and be able better to handle infested areas, that the injury may be reduced to a minimum. ' 88491°—Bull. 733—16 2 FARMERS’ BULLETIN 733. pearance of the plants, which may later produce 50 per cent or more of a normal yield. The wireworms are ravenous feeders, often cutting off all the roots of a plant. They are especially destructive during the two months before they transform to adults. A single half-grown wireworm is capable of killing a young corn sprout and severely injuring a plant from 6 to 8 inches in height. Therefore it can be seen that when there is a concentrated attack by many wireworms in one hill the plants have but small chance of surviving. DESCRIPTION OF THE INSECT IN ITS DIFFERENT STAGES. The parent of the corn and cotton wireworm (fig. 1, @) is a small dark brown click-beetle, or “ snapping beetle.” measuring about one- 2 fourth of an inch in length. The eggs (fig. 2) laid by this beetle are white and nearly round; when first deposited they are translucent, but in a day or two become opaque. The young wireworms, or larve, en after hatching from the eggs are minute, measuring FIG. 2 Eee ie =©from an eighth to three-sixteenths of an inch in Wierd (oriee «= Length. When from half to full grown (fig. 1, 0) nal.) they may be described as “soft, membranous, and elongate.” The body, which is usually white, is apparently composed of 26 segments, or joints, every third segment being swollen. The last segment is simply pointed. The head, which is yellow, is long and slender, and has a pair of prominent, dark brown jaws. When full grown these larve measure about an inch in length and are but slightly thicker than pack thread. The pupe (fig. 3), to which the larve change before becoming adult beetles, have the same general color as the larve and are about five-sixteenths of an inch long and nearly an eighth of an inch thick. Each pupa eccurs in a small earthen chamber constructed by the larva. All stages of the insect are spent in the ground ex- cept the adult or beetle, which only enters it at the time of egg deposition. .There are a number of other species of wireworms 1a pe which are often found associated with this wireworm _ resting stage, of . : the corn and about the roots of corn and others of its food plants. cotton wire- 5 . eve worm. Much The corn and cotton wireworm can be easily distin- eniargea. (Origi- guished from these, however, by its light creamy color ™!) and threadlike form, as most other wireworms are stouter and usually either reddish or brownish. WHERE THE INSECT OCCURS. Reports show that the corn and cotton wireworm has been de- structive in the Carolinas, Illinois, Missouri, Arkansas, and Missis- CORN AND COTTON WIREWORM AND ITS CONTROL. 3 sippi. This would indicate a wide distribution, probably a wider one than the mere records reveal, and it is possible that the species may occur throughout the entire eastern half of the United States. Its occurrence is closely related to the distribution of soils of light sandy type, as it is known that the immature stages exist only in such soils. Occasionally an adult has been collected several miles from sandy locations, but its presence there was more than likely due to its own flight from the field of its origin. In some localities this species is referred to as the “ sandy-spot wireworm.” PLANTS ATTACKED. Cotton and corn constitute the principal food plants of this wire- worm, and of the cereal and forage crops in the South the greatest damage is done each year to corn. The wireworms, besides feeding upon the roots of corn and cotton, are known to attack oats, rye, cowpeas, crab grass, and Johnson grass. Sweet potatoes, peanuts, tobacco, watermelons, and the roots of a wild bamboo are also among the food plants of this wireworm. The adults have been observed feeding on stems of cowpeas and on young, tender leaves of corn and crab grass. CHARACTER OF THE INJURY. ' Corn plants infested by this wireworm become wilted and stunted, with leaves of a bluish shade, brown at the tips, which stand out from the stalks stiffly instead of bending over gracefully as in a healthy plant. Deprived of most of the roots through the work of the larve of this wireworm, the plant can be pulled up with little effort. Weak plants soon succumb, leaving gaps in the rows, but the more vigorous plants put forth new roots in abnormal numbers. These are matted together and distorted, and although the plants survive, only “nubbins” are produced. The infestation is not con- fined to the impoverished areas, for there may be larve among the roots of tall and apparently healthy plants. Rolling land infested by this insect presents a patchy appearance, the sandy knolls stand- ing out distinct and bare, although overgrown later with weeds, particularly crab grass, briers, and morning-glories. For a long time there was a theory among farmers that lightning caused the injury to corn which is now rightly attributed to this wireworm. In the case of cowpeas, the fibrous roots suffer most, the thicker roots being perforated, so that the plants become yellow and dwarfed, and fail to vine. Cotton is injured in the early stages by larvee boring into the seed and injuring the very young plants, checking the growth so much that the plant dies or struggles along only to produce little or no cotton. 4 FARMERS” BULLETIN 133. LIFE HISTORY OF THE SPECIES. Beetles of the corn and cotton wireworm (fig. 1, @) are abroad in the fields from early June until the last of August. The eggs (fig. 2), which are laid in groups of from 3 to 20 in the soil about the roots of corn, cowpeas, and other food plants, are deposited, for the most part, during late June and July. These hatch in from 8 to 11 days into the young wireworms or larve (fig. 1, 6) which immediately com- mence feeding upon the roots. The exact duration of the period of development in the soil has not yet been determined, but the informa- tion now at hand indicates that the species lives in the larval stage for two years and possibly three. It is true that adults are to be found each year, but this is probably due to overlapping broods. During May or June each full-grown larva constructs a small earthen cell in the soil and in this it changes to a pupa (fig. 3). The pupal stage averages 12 days in length and during this time the pupa is almost motionless and takes no food. After this it transforms to the adult or beetle. As is usually the case, the duration of the egg and pupal stages varies with temperature and moisture conditions. HABITS OF THE LARVA, OR WIREWORMS. The larve, or wireworms, feed upon the roots of their food plants throughout the summer months and up to about the first of October, and during this time are found within 18 inches of the surface of the ground, the depth depending upon the moisture content of the top - soil. During a hot, dry spell the wireworms remain from 12 to 18 inches below the surface, but after a rain they can be found within 2 inches of the surface. With the approach of cold weather they begin a general down- ward movement, which accounts for the farmer’s inability to locate them during the late fall and winter months. At Charleston, Mo., December 1, 1914, they were found in the sand at the remarkable depth of 5 feet. This appeared to be the average depth at which they remained during the winter in this locality, observations showing the depth to vary from 4 to 6 feet. From these facts it will be seen that fall or winter plowing would be useless as a control or remedial measure. By the last of February in some localities, or as soon as winter breaks up, the larve gradually make their way to within 2 to 3 feet of the surface. By the middle of April they are numerous within 6 inches of the surface of the ground. From the time the larve travel downward in the fall until they return to the top soil they eat prac- tically nothing. In laboratory experiments, larvee remained alive and healthy in cages of moist pure sand, without organic food, for six months. CORN AND COTTON WIREWORM AND ITS CONTROL. 5 The larve are quick of movement and wriggle vigorously when disturbed. In indoor rearing cages they are found to be keenly sus- ceptible to an overabundance of moisture, and, too, will die if the cage soil is allowed to get excessively dry. Cannibalism is common among them, especially under artificial rearing conditions, but the fact that as many as 106 larvee have been found in one hill of corn is evidence that this habit does not exist to any great extent in the field when there is plenty of plant food at hand. HABITS OF THE ADULTS, OR BEETLES. The adults, or beetles, are also very quick of movement. Imme- diately: upon being disturbed they “snap” themselves and fall to the ground from the leaf or stem upon which they are resting. On the ground they feign death for a few moments, then quickly scamper off to a hiding place. The adults feed very little, hence any injury which they might cause would be hardly perceptible. They evidently fly well, as they have been collected in quantities around lights at night. This would probably explain the fact that adults have been collected several miles from the nearest sandy spot or field. The author, however, has never seen them fly in the day- time. The female beetles will not deposit eggs in soil which is crusted over or baked, but leave such a field and search for one which is covered by a dust mulch, or which has recently been plowed. This fact is important and should be taken into account when control measures are being considered, since cultivation at the time the beetles are most numerous means that excellent conditions are given the females for depositing their eggs. NATURAL ENEMIES. Comparatively few natural enemies of this wireworm have been noted. No internal parasites have been reared from any stage of the species. Birds feed upon all kinds of wireworms including those of the genus Horistonotus. INEFFECTUAL REMEDIAL MEASURES. PLOWING. Late fall and winter plowing as a method of reducing the numbers of the pest by turning up and exposing the larve to the elements is of no value, as the wireworms are at this time at such depths in the soil that they would not be disturbed by the plowing. Plowing or cultivating for this purpose at other times of the year is of little avail as the wireworms are so quick of movement that almost as soon oaerace 6 FARMERS’ BULLETIN 733. as exposed they are again hidden in the loosened soil. Even chickens or turkeys are not sufliciently alert to catch many. TRAPPING ADULT BEETLES. Trapping the beetles at night by means of strong lights above open vessels containing water or kerosene would in no way prove practical, especially on a large scale. POISONING. Killing the wireworms by placing poisoned baits in the soil around the hills of corn is not practical, nor will the treating of seeds with poisons or repellents assist in protecting the plants from wireworm attacks. Turning under wood ashes, as a remedy against wireworms, has proved to be of no avail. EFFECTIVE CONTROL AND REMEDIAL MEASURES. The following control measures are formulated from the study of the habits of the insect, and are based on results of such measures carried on over a period of two years. It must be remembered that as this species has been under investigation for only three years, the following remedial measures are subject to more or less modification. HASTENING EARLY PLANT GROWTH. The most important factor in reducing injury by this wireworm is the employment of methods which hasten early plant growth in the spring, the object of stimulating growth being to enable the plants the better to withstand the attacks of the wireworms. In the case of corn this consists of early planting—at least by April 20 for southeastern Missouri and northeastern Arkansas—followed by fre- quent cultivation until the middle of June. CROP ROTATION. Any system of crop rotation after harvesting the corn may be carried out, and a winter cover crop such as wheat or rye is advised. Pasturing this during winter months and turning it under in the spring is very beneficial, since humus is thus added and the sandy soil is thereby stiffened. An infested field should not be planted to corn two years in succession. If a catch crop of red clover can be obtained it is an excellent one to come in the rotation for two or three years. Such com- binations as wheat and clover are to be recommended for south- eastern Missouri, as they not only afford two crops a year from the CORN AND COTTON WIREWORM AND ITS CONTROL. yf same field, but also permit the soil to remain undisturbed during the period when the female beetles are laying their eggs. As stated elsewhere in this bulletin, the females prefer loose soil for egg deposi- tion, especially soil which has been recently cultivated or plowed. A system of handling the ground and crops so that the soil will not be disturbed from the middle of June until the middle of August is one of great importance, and it may prove to be the most beneficial step in eradicating the wireworms from an infested area. This may be brought about by omitting from the rotation such crops as would normally require summer cultivation. The supposition that an infestation of the corn and cotton wire- worm is worse following cowpeas seems to be unfounded. MANURING. The manuring of infested areas has long been recommended as the best control measure. The theory was advanced, especially by some farmers, that the manure turned under is actually distasteful to the larvee and kills them outright. Although this is not the case, never- theless the turning under of manure and cover crops has the effect of adding humus to the top soil; and, as it is known that the larve can not long survive except in sandy soils, it is well to spread as much manure as possible on infested areas and to turn it under. LAND RESTING. If it were practicable to allow the infested fields to lie idle, or “lay out,” as it is termed, for a period of three years, this would no doubt prove the most effective means of getting rid of the pest, since by leaving the ground undisturbed a crust would be formed on the surface through which the majority of adult wireworms could not emerge. It would also serve to prevent the few emerging adults, as well as those flying in from other fields, from entering the soil for egg deposition. However, this practice naturally will not often appeal to the farmer. SUMMARY OF CONTROL MEASURES. (1) Plant infested fields to such crops as do not require summer cultivation, such as clover, cowpeas, soy beans, or grasses. (2) Add humus to the light sandy spots by turning under manure and cover crops. (3) If grain crops be planted, allow stubble to remain until the middle of August. (4) If corn must be grown, plant early and do everything possible to hasten rapid growth. Do not plant corn two years in succession. PUBLICATIONS OF U. S. DEPARTMENT OF AGRICULTURE RELAT- ING TO INSECTS INJURIOUS TO CEREAL AND FORAGE CROPS. AVAILABLE FOR FREE DISTRIBUTION. Cotton Bollworm. (Farmers’ Bulletin 290.) Common White Grubs. (Farmers’ Bulletin 543.) The Chalcis-fly in Alfalfa Seed. (Farmers’ Bulletin 636.) The Grasshopper Problem and Alfalfa Culture. (Farmers’ Bulletin 637.) The Hessian Fly. (Farmers’ Bulletin 640.) Alfalfa Attacked by the Clover-root Curculio. (Farmers’ Bulletin 649.) The Chinch Bug. (Farmers’ Bulletin 657.) Wireworms Destructive to Cereal and Forage Crops. (Farmers’ Bulletin 725.) The True Army Worm and its Control. (Farmers’ Bulletin 731.) The Hessian Fly Situation in 1915. (Office of Secretary Circular 51.) The Spring Grain Aphis or “ Green Bug” in the Southwest and the Possibilities of an Outbreak in 1916. (Office of the Secretary Circular 55.) Southern Corn Rootworm, or Budworm. (Department Bulletin 5.) Western Corn Rootworm. (Department Bulletin 8.) The Oat Aphis. (Department Bulletin 112.) The Alfalfa Caterpillar. (Department Bulletin 124.) Clover Mite. (Entomology Circular 158.) Clover-root Cureulio. (Entomology Bulletin 85, pt. IIT.) Maize Billbug. (Entomology Bulletin 95, pt. II.) FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS. The Larger Corn Stalk-borer. (Farmers’ Bulletin 634.) Price, 5 cents. The Southern Corn Leaf-Beetle. (Department Bulletin 221.) Price, 5 cents. The Sharp-headed Grain Leafhopper. (Department Bulletin 254.) Price, 5 cents. The Pea Aphis with Relation to Forage Crops.. (Department Bulletin 276.) Price, 15 cents. Joint-worm. (Entomology Circular 66.) Price, 5 cents. Some Insects Affecting Production of Red Clover Seed. (Entomology Circular 69.) Price, 5 cents. Wheat Strawworm. (Entomology Circular 106.) Price, 5 cents. Western Grass-stem Sawfly. (Entomology Circular 117.) Price, 5 cents. Clover Root-borer. (Entomology Circular 119.) Price, 5 cents. Alfalfa Gall Midge. (Entomology Circular 147.) Price, 5 cents. Lesser Clover-leaf Weevil. (Entomology Bulletin 85, pt. I.) Price, 5 cents. Sorghum Midge. (Entomology Bulletin 85, pt. IV.) Price, 10 cents. New Mexico Range Caterpillar. (Entomology Bulletin 85, pt. V.) Price, 10 cents. Contributions to Knowledge of Corn Root-aphis. (Entomology Bulletin 85, pt. VI.) Price, 5 cents. So-called “Curlew Bug.” (Entomology Bulletin 95, pt. IV.) Price, 10 cents. False Wireworms of Pacific Northwest. (Entomology Bulletin 95, pt. V.) Price, 5 cents. . Alfalfa Looper. (Entomolcegy Bulletin 95, pt. VII.) Price, 5 cents. Leafhoppers Affecting Cereals, Grasses, and Forage Crops. (Entomology Bul- letin 108.) Price, 20 cents. Spring Grain-aphis or Green Bug. (Entomology Bulletin 110.) Price, 25 cents. Preliminary Report on Alfalfa Weevil. (Entomology Bulletin 112.) Price, 15 cents. : 8 WASHINGTON : GOVERNMENT PRINTING OFFICE: 1916 FARMERS’ BULLETIN. WasuineTon, D. C. 734 JUNE 10, 1916 Contribution from the Bureau of Entomology, L. O. Howard, Chief. CONTENTS. Page. Page Introduction >: Spe Ses tei. ee eee 1 | Care and location of traps..............-...-. 12 kings offliescaught-c. 926 Ao oer. oo) os Se AS MCey iyi PADenssas cee. ke eeeme 2.8 12 BYES CMULADSs veces see as ois 2 See Sn iP EOISONGCIDAILS: arm eae. ~. Oe. s 13 matisdor tyaps. =f! fey deere ce bs. . 5. 222555: Oss Canton ser: 2. Fee sae oe 2 Pas e Ht 3.5.3 13 Bait containers. 25... . ost dace de aesace 12 FLYTRAPS AND THEIR OPERATION. By F. C. BisHopp, Hntomological Assistant. INTRODUCTION. Flytraps have a distinct place in the control of the house fly and other noxious fly species. There is a general tendency, however, for those engaged in combating flies to put too much dependence on the flytrap as a method of abating the nuisance. It should be borne in mind that flytrapping is only supplementary to other methods of control, most notable of which is the prevention of breeding either by completely disposing of breeding places or by treating the breeding material with chemicals.? It may be said that there are two main ways in which flytraps are valuable: (1) Catching flies which come to clean premises from other places which are insanitary and (2) capturing those flies which in- variably escape in greater or less numbers the other means of destruc- tion which may be practiced. Furthermore, the number of flies caught in traps serves as an index of the effectiveness of campaigns against breeding places. 1 Results obtained in experiments with the use of chemicals against fly larve in manure are presented in Bulletins Nos. 118 and 245 of the Department of Agriculture. The biology of the house fly and the various methods of control are discussed in Farmers’ Bulletin 679. Nore.—tThis bulletin is intended to give directions for the use of a supplementary means of controlling flies; it is adapted to all parts of the United States. 38492°—Bull. 734—16 2 FARMERS’ BULLETIN 1734. Fly trapping should begin early in spring if it is to be of greatest value. Although comparatively few flies are caught in the early spring, their destruction means the prevention of the development of myriads of flies by midsummer. \ KINDS OF FLIES CAUGHT. The various species of flies which are commonly annoying about habitations or where foodstuffs are being prepared may be divided roughly into two classes: (1) Those which breed in animal matter, consisting mainly of the so-called “Dblowflies”; and (2) those which breed in vegetable as well as in animal matter. In the latter group the house fly is by far the most important. The stable fly is strictly a vege- table breeder, as are also certain other spe- cies which occasionally come into houses and may in rare cases con- taminate foodstuffs. The stable fiy, which breeds in manure or decaying vegetable ENN BN) N N N ANY Fic. 1.—Conical hoop flytrap; side view. A, Hoops form- matter, and the horn ing frame at bottom. B, Tloops forming frame at top. iy which breeds in C, Top of trap made of barrel head. D, Strips around ee door. H, Door frame. F, Screen on door. G, Buttons COW manure, are blood- holding door. J7, Screen on outside ofatrap?, J; Strips on sucking spec 1 es, and side of trap between hoops. J, Tips of these strips pro- yee i Z jecting to form legs. K, Cone. L, United edges of screen Call be caught in ordi- forming cone. MV, Aperture at apex of cone: (Author's nary flyt ‘aps in com- illustration.) ‘ paratively small num- bers only. The kind of flies caught depends to a considerable extent on the material used for bait. In general the house fly and other species which breed in vegetable matter are attracted to vegetable substances, while the blowflies will -come most readily to animal matter. This rule, of course, is not absolute, as flies are less restricted in feeding than in breeding habits, and, as is well known, the house fly is attracted to a greater or less extent to any moist material, especially if it has an odor. \ FLYTRAPS. AND. THEIR OPERATION. 3 TYPES OF TRAPS. _ The same general principle is involved in nearly all flytraps in use, though superficially they may appear quite different. The flies are attracted into a cage, as it were, by going through a passage the entrance of which is large and the exit small, so there is little chance of the flies, once in, finding their way out again. This principle is modified to fit different conditions. For instance, the window trap, devised by Prof. C. F. Hodge, catches the flies as they endeavor to enter or leave a building; the garbage-can trap, for which Prof. Hodge is also to be credited, catches the flies that have entered gar- bage cans; and the manure-box trap retains the flies bred from in- fested manure put into the box. The attractant used to induce flies to enter traps may consist of (1) food, as in baited traps; (2) odors, as in window traps placed in windows from which odors are emitted; and (3) light, as in traps on manure boxes. Of course light is an important factor in the suc- cess of all traps, for, as is well known, flies have a marked tendency to go toward the lhght, and they usually enter the trap by flying toward the light after having been attracted beneath it by bait or after entering a room in search of food. : CONICAL TRAPS. A number of traps of this general type are on the market, but most of these are of small size. Nearly all are constructed with a dome instead of a cone, and on this account the catching power is reduced about one-third. Moreover, the farmer, dairyman, or anyone with a few tools can construct traps at a small fraction of the sale price of ready-made ones. THE CONICAL HOOP TRAP. A trap which appears from extensive tests made by Mr. E. W. Laake and the author to be best for effective trapping, durability, ease of construction and repair, and cheapness may be made as follows: The trap consists essentially of a screen cylinder with a frame made of barrel hoops, in the bottom of which is inserted a screen cone. The height of the cylinder is 24 inches, the diameter 18 inches, and the cone is 22 inches high, and 18 inches in diameter at the base. Material necessary for this trap consists of four new or secondhand wooden barrel hoops, one barrel head, four laths, 10 feet of strips 1 to 14 inches wide by one-half inch thick (portions of old boxes will suffice), 61 linear inches of 12 or 14 mesh galvanized screen- ing 24 inches wide for the sides of the trap and 41 inches of screening 26 inches wide for the cone and door, an ounce of carpet tacks, and two turn-buttons, which may be made of wood. The total cost of the material for this trap. if all is bought new at retail prices, is about 65 cents. In practically all cases, however, the barrel hoops, barrel head, lath, and strips can be obtained without expense. This 4 FARMERS’ BULLETIN 734. would reduce the cost to that of the wire and tacks, which would be 45 cents. If a larger number of traps are constructed at one time the cost is considerably reduced. One of these traps is illustrated in figures 1 and 2. In constructing the trap two of the hoops are bent in a circle (18 inches in diameter on the inside), and nailed together, the ends being trimmed to give a close fit. These form the bottom of the frame (4), and the other two, prepared in a similar way, the top (2). The top ((C) of the trap is made of an ordinary barrel head with the bevel edge sawed off sufficiently to cause the head to fit closely in the hoops and allow i Ye | Yo J | f ase | L, ~ - = ZZ d Fg =I Yi, + —* Vy owe i” Y yj = = iit sf _——_—— pbk if fi IY, Mf Z Z ¢ YC jg q] of OG, <) ‘Z i ——— —— meant iY Z Jomo Jip eG Ly Fic. 2.—Conical hoop flytrap ; top view. Letters designate parts as in figure 1. (Author's illustration.) secure nailing. A square, 10 inches on the side, is cut out of the cen- ter of the top to form a door. The portions of the top (barrel head) are held together by inch strips (77) placed around the opening one- half inch from the edge to form a jamb for the door. The door con- * sists of a narrow frame (£) covered-with screen (/) well fitted to the trap and held in place (not hinged) by buttons (G@). The top is then nailed in the upper hoops and the sides (47) formed by closely tacking screen wire on the outside of the hoops. Four laths (7) (or hight strips) are nailed to the hoops on the outside of the trap to act as supports between the hoops, and the ends are allowed to pro- FLYTRAPS AND THEIR OPERATION. 5 ject 1 inch at the bottom to form legs (/). The cone (4) is cut from the screen and either sewed with fine wire or soldered where the edges meet at (Z). The apex of the cone is then cut off to give an aperture (J/) 1 inch in diameter. It is then inserted in the trap and closely tacked to the hoop around the base. The construction of a cone of any given height or diameter is quite simple if the following method be observed. It is best to cut a pattern from a large piece of heavy paper, cardboard, or tin. Figure 3 illustrates the method of laying out a cone of the proper dimensions for the above trap. An ordinary square is placed on the material from which the pattern is to be cut; a distance (22 inches) equal to the height of the cone is laid off on one leg of the square at A, and a distance (9 inches) equal to one-half of the diameter of the base of the cone is laid off on the other leg at 2, Fic. 5.—Method of laying out a pattern for the construction of a cone. Cut out on curved line C to # and on dotted lines from A to C and A to HE. (Author's illustration.) and a line is drawn between the points A and &. With the distance between these points as a radius and with the point A as a center, the portion of a circle C D, is drawn. With a pair of dividers, the legs of which are set 1 inch apart, or with the square, lay off as many inches on the are C' D, starting at (, as there are inches around the base of the cone, which in this case is about 564 inches, reaching nearly to the point #. Then add one-half inch for the lapping of the edges of the cone, and one-half inch which is taken up when the cone is tacked in, thus making a total distance from C to #' of 574 inches. Draw a line from A to ( and another from A to /, and cut out the pattern on these lines and on the are from (' to /, as shown in figure 3. The edges AC and AF are then brought together, lapped one-half inch and sewed with wire or soldered. After the aperture 6 FARMERS” BULLETIN 734. of the cone is formed by cutting off the apex, as previously described, it is ready for insertion in the trap. In order to figure the distance around the base of a cone of any given diameter, multiply the diameter by 3.1416 or 3}. The height of the legs of the trap, the height of the cone, and the size of the aperture in the top of the cone, each are of importance in securing the greatest efficiency. OTHER FORMS OF CONICAL TRAPS. Conical traps with steel frames are satisfactory, but they are less easily resereened and it is more difficult to keep the lids closely fitted. These, of course, can be constructed only by shops with con- siderable equipment. Traps _ constructed with a wooden disk about the base of the cone, and a similar disk around the top to serve as a frame, or those with a square wooden frame at the bottom and top with strips up the corners are fairly satisfac- tory. It should be borne in mind that the factor which de- termines the number of flies caught is the ic. 4.—Tent flytrap. When the trap is set up the screen box, A, fits on the base, B, and two pans of bait are placed beneath the tent. ©, Hole in screen at apex of diameter of the base tent. (Original.) . ic vena of the cone, if other things are equal. Therefore the space taken up by the wooden framework is largely wasted, and if it is too wide it will have a deterrent effect on the flies which come toward the bait. For this reason it is advisable that the wood around the base of the cone should be as narrow as consistent with strength—usually about 3 inches. lnder no condition should the sides or top of the trap be of solid material, as the elimination of hght from the top or sides has been found to decrease the catch from 50 to 75 per cent. TENT TRAPS. The tent form of trap has been widely advocated in this country, but recent experiments indicate that it is much less efficient than the FLYTRAPS AND’ THEIR OPERATION. 3 cone trap, and usually as difficult to construct and almost as expen- sive. The size of these traps may vary considerably, but one con- structed according to the dimensions given in figure 4+ will be found most convenient. The height of the tent should be about equal to the width of the base, and the holes ((’) along the apex of the tent should be one-half to three-fourths of an inch in diameter and 1 inch apart. The box (2) should be provided with hooks to pass - through eyes on the base (4). Small blocks 1 inch thick are nailed beneath the corners of the tent frame to serve as legs. GARBAGE-CAN TRAPS. As previously mentioned, Prof. Hodge has adapted the cone trap to use on the lids of garbage cans. It is not advisable to use this trap except where garbage cans are sufficiently open to admit flies. In such cases a hole may be cut in the lid of the can and one of the small balloon traps which are obtainable on.the mar- ket attached over the hole. To make the trap effective the edges of this hd should extend well down over the top of the can. The lid should be held up slightly so as to allow the flies to pass under, but not - high enough to admit direct hght. Practically speak- c ing, the garbage forms the Vic, 5.—Top of garbage can with small balloon fly- i i trap attached. (Original.) bait for this trap, and when inside the can the flies are attracted to the light admitted through the trap. It is really advisable to have the garbage cans fly proof, so as to prevent danger of fly breeding within them rather than to depend on traps on the lids, which necessarily allow odors to escape. A garbage can with a trap attached is illustrated in figure 5. MANURE-BOX TRAPS. Manure pits or boxes are desirable for the temporary storage of manure, especially in towns and cities. These have been widely advocated, but the difficulty has been that manure often becomes infested before it is put into them, and flies frequently breed out before the boxes are emptied and often escape through the cracks. To obviate these difficulties a manure box or pit, with a modified 8 FARMERS” BULLETIN 1734. tent trap or cone trap attached, is desirable. Mr. Arthur Swaim, of Florida, has devised a form of manure trap consisting of a series of screen tents with exit holes along the ridges of these, over which is a screen box. The latter retains the flies as they pass through the holes in the tents. The entire trap is removable. In order to retain the fertilizing value of manure to the greatest extent it is advisable to exclude the air from it as much as possible and to protect it from the leaching action of rains. This being the case, there is really no necessity for covering a large portion of the. top of the box with a trap, but merely to have holes large enough to attract flies to the light, and cover these holes with ordinary conical traps, with the legs cut off, so the bottom of the trap will fit closely to the box. The same arrangement can be made where manure is kept in a pit. In large bins two or more holes covered with traps should be provided for the escape of the flies. Manure boxes should be used by all stock owners in towns and cities, and they are also adaptable to farms. The size of the manure bin should be governed by the individual needs, but for use on the farm it is desirable to make it large enough to hold all of the manure produced during the busiest season of the year. A box 14 feet long, 10 feet wide, and 4 feet deep will hold the manure produced by two horses during about five months. About 2 cubic feet of box space should be allowed for each horse per day. The bin should be made of concrete or heavy plank. When the latter is used the cracks should be battened to prevent the escape of flies. The bin may have a floor or it may be set in the ground several inches and the dirt closely banked around the outside. For the admission of the manure a good- sized door should be provided in either end of a large bin. .=.............. 12 Native North American ants of temperate Protection from the carpenter ant....... 12 PORUMISS . < neesoe a eaise See se sie siae'cte' =: 7 Garden and lawn ants as house pests... - 8 INTRODUCTION. There are now in North America a considerable number of species of ants which under favoring conditions may inhabit dwell- ing houses or other heated buildings, constructing their nests and breeding continuously in the woodwork or masonry, or in articles of furniture or of ornament, and subsisting on food materials which they find about kitchens and pantries or scattered in living rooms. Other species nesting in gardens and lawns or under adjacent walks may occasionally enter houses as foragers or as accidental guests. It is interesting to note that, of the ants which in North America frequent houses and construct their nests therein, practically all are of tropical origin, and most of them are Old-World species. 1 The authority for the scientific names and the source of many records of the less well- known house ants given in this bulletin is the notable work on American ants by Dr. W. M. Wheeler, entitled “Ants: Their Structure, Development, and Behaviour” (1910). Dr. Wheeler has also read the text of this bulletin and furnished some notes not available in print. 39286°—16 5 FARMERS’ BULLETIN 140. It is a matter of further interest that, with the exception of the European meadow ant, practically all of the ants which have been introduced into North America, either from the Old World or from South America, are such tropical species and potential house pests. All of these introduced species have been brought to North America and many of them given cosmopolitan distribution through the agency of commerce. The tropical ants in their native countries are still normally outdoor species, although in the Tropics they also frequent human habitations, including ships, and, by colonizing in ships’ cargoes, are easily given world-wide distribution. Some of Fic. 1.—The little black ant (Monomorium minimum): a, Male; b, pupa; c, female; d, same with wings; e, worker; f, larva; g, eggs; group of workers in line of march below. - All enlarged, the lettered illustrations all drawn to the same scale. (Original.) these Old-World species have become established as out-of-door species in the New-World Tropics, but in temperate regions they are able to survive only in dwellings, hothouses, mills, or other struc- tures where the requisite warmth is maintained. The ability of these imported tropical species to maintain themselves is largely due to the protection from competition with our native species afforded by this house-dwelling habit. None of these ants, with the exception, in rare instances, of the carpenter ant, are so destructive to household effects or supplies as they are annoying from the mere fact of their presence and their HOUSE ANTS: KINDS AND METHODS OF CONTROL. 2] faculty of “getting into” articles of food, particularly sugars, sirups, cakes, candies and other sweets, and cooked foods of animal crigin. Having once gained access to articles of this sort, the dis- covery is at once reported to the colony, and in an incredibly short time the premises may be swarming with these unwelcome visitors. KINDS OF NORTH AMERICAN HOUSE ANTS. The different kinds of North American house ants may be grouped on the basis of origin as follows: (1) Tropical Old-World ants, rep- resented by 12 species; (2) ants introduced from the New-World Tropics, represented by 5 species; (3) native North American ants of temperate regions which occasionally inhabit dwelling houses, repre- sented by 2 species; and (4) such occasional garden and lawn ants as may from time to time become accidental house pests by extending their forays into dwelling houses in quest of food, of which 4 native North American species are discussed, and also the introduced Euro- pean meadow ant. INTRODUCED TROPICAL OLD-WORLD ANTS. The little red ant,‘ or Pharaoh’s ant (fig. 2), is the best known house species. It has attained a thoroughly cosmopolitan distribu- tion and has been domesticated so long that it is now difficult to de- termine its exact origin, except to place it generally in the Old-World Tropics. It was originally a soil ant, nesting out of doors in warm countries, and doubtless continues this habit in the tropics of both hemispheres. In temperate regions it passes its entire existence in heated houses. Three other species of the same genus of Old-World tropical ants are recorded as having been brought to our shores and as having gained foothold, occasionally in dwellings.? None of these species have, however, so far established any important record in this coun- try as house pests, although they may be expected to appear at any time in dwelling houses and other heated structures, particularly in the southern United States, and possibly farther north along the Atlantic seaboard. One of these, Monomorium salomonis, is stated to be the most abundant of North African ants, and to have been widely distributed by commerce and to occur in most tropical and subtropical countries. A native species of the same genus,? known as the little black ant, is referred to elsewhere. Two Old-World agricultural or harvester ants* have been brought to this country by commerce and are now fairly well established in 1 Monomorium pharaonis WL. 2 Monomorium salomonis l., Monomorium destructa Jerdon, and Monomorium floricola Jerdon. 3 Monomorium minimum Buckley. 4 Solenopsis geminata Fab. subspecies rufa Jerdon and Pheidole megacephala Fab. 4 FARMERS’ BULLETIN 1740. tropical America, and are potential house pests. One of these, Phei- dole megacephala, was formerly the important house ant of Madeira, | occurring in prodigious numbers throughout the southern portion of the island and up to an elevation of 1,000 feet, nesting out of doors under nearly every stone, and in houses generally. It is stated also that this ant is very common in the Bermudas and West Indies and will probably be found in Florida, and that wherever it gains foot- hold in subtropical countries it is able to propagate very rapidly and Fic, 2.—The little red or Pharaoh’s ant (Monomorium pharaonis) ; a, Queen or female; b, worker. Both drawings enlarged to the same scale. (Original.) to exterminate the indigenous ant fauna; in fact, several instances of this kind have been noted. This ant, on the other hand, has itself lately been driven out and practically exterminated in Madeira by the Argentine ant,’ which latter ant has also, in New Orleans and elsewhere in the United States, similarly displaced our native ants. As North American house ants, however, neither of these Old-World - harvester ants has so far assumed any importance, although both probably occur in Florida. 1 Iridomyrmex humilis Mayr. HOUSE ANTS: KINDS AND METHODS OF CONTROL. 5 Six other Old-World tropical ants have been recorded as introduced house-infesting species in North America.t’ These, like other Old- World ants, have been brought in through the agency of commerce and have gained foothold in tropical America and are occasionally found nesting in hothouses and other heated structures in temperate regions. One of these ants, Prenolepis longicornis, a slender, black species with unusually long legs and antenne or “ feelers,” has earned the common name of “crazy ant” from its habit of running about, usually singly and apparently aimlessly, with a quick, jerky motion. This ant has long been a common species in the greenhouses of tem- perate Europe and America, and in some of these, as in the Jardin des Plantes in Paris, it has been a permanent resident for more than 40 years. It has acquired a footing in tropical Florida, and probably also in other localities in the Gulf States, and has been reported as infesting, even to the top floors, large apartment build- Fic. 3.—An introduced tropical Old-World ant, Plagiolepis longipes. Enlarged. (After Wheeler.) ings in New York City, and also as occurring in hotels and flats in Boston. It is a common house ant in the District of Columbia. India is believed to be the original home of this ant, whence it has been carried to all tropical countries in ships, and it has been ac- companied in its wanderings by three insect messmates, namely, two beetles and a small cricket. A related species, Prenolepis vividula, is a common greenhouse pest in Europe and is reported as having been found in greenhouses in this country; in one instance as far north as Canada. Another of these Old-World ants, Plagiolepis longipes (fig. 3), will probably ultimately come into prominence as a house species on this continent. Its original home is given as Cochin China, but it has already estab- lished a foothold in widely separated parts of the world. On the island of Reunion, for example, it is very abundant and is reported to be driving out some of the primitive species. It has also been recorded on this continent from Todos Santos, Lower California. 1Tetramorium guineense Fab., Tetramorium simillimum Roger, Tapinoma melanoce- phalum Fab., Prenolepis longicornis Latr., P. vividula Nyl., and Plagiolepis longipes Jerdon. 6 FARMERS” BULLETIN 740. INTRODUCED TROPICAL NEW-WORLD ANTS. Of the ants introduced into North America from the New-World Tropics the one of greatest economic importance is what has now come to be generally known as the Argentine ant (fig. 4)1 from its supposed Argentine origin. It is known, however, to be a serious pest in Brazil and Uruguay, as well as in Argentina. It is some- times also called the New Orleans ant, from the fact that it gained its first foothold from colonies brought in, presumably from Brazil, Fic. 4.—The Argentine ant (Jridomyrmer humilis). 1, Wingless female. 2, Worker. 2 3, Immature stages: a, Eggs; b, young larva; ¢, full-grown larva; d, pupa, side view; e, pupa, ventral view; f, pupa, dorsal view. 4, Male. .All enlarged to the same scale, (Original.) by some ships’ cargoes to the port of New Orleans. It is a much worse house pest than even the little red ant or any of the other house ants and is in addition a very serious enemy of field and garden crops and orchard trees. Ithasrapidly spread from the point of introduction throughout Louisiana and has been carried by traffic to California, where it has become a serious pest in citrus orchards in the southern part of the State, and in houses as far north as San Francisco. It is undoubtedly destined to extend its outdoor range 1Jridomyrmer humilis Mayr. HOUSE ANTS: KINDS AND METHODS OF CONTROL. 7 wherever climatic conditions permit and as a house and greenhouse pest over a much wider area. Its rdéle as an exterminator of native ants in the New Orleans district and in the island of Madeira has already been referred to. It is the only one of the imported tropical ants which causes any large monetary losses. The other species, as elsewhere noted, are for the most part merely annoying. Four other species of ants from tropical America have gained, through the agency of commerce, some foothold as house pests in the southern and eastern United States, and manage to live for con- siderable periods of time in northern heated houses.* One of these, Prenolepis fulva subspecies pubens, has been recorded from the District of Columbia, where it was found infesting one of the hothouses of the Department of Agriculture. It is believed to bea native of Brazil, but now occurs quite abundantly in Cuba and other West Indian Islands. It is still a comparatively rare house pest, how- ever, in temperate regions of North America, and, except in the Tropics, undoubtedly can not survive outside of heated buildings. NATIVE NORTH AMERICAN ANTS OF TEMPERATE REGIONS. Only one North American ant of temperate regions has become a true house dweller and pest. This distinction belongs to the little “thief ant,’? a native of our Northern and Eastern States. The workers of this ant are very small, and yellowish in color. They frequently, as do also Old-World species of the genus, inhabit the gallery walls of other and larger ants, where they are apparently unnoticed, and kill and eat the helpless larve and pupe of their ap- | parently unconscious hosts. The thief ant may, however, lead an in- dependent existence, and has been reported as a frequent pest in dwellings. It feeds on any animal matter, including dead insects, and has been recorded as attacking the sprouting kernels of Indian corn. This species can be readily distinguished from the little red, or Pharaoh’s, ant by its much lighter color and smaller size.2 This species is reported by C. H. Popenoe, of the Bureau of Entomology, United States Department of Agriculture, as nesting in houses very much as does the little red ant, colonies of the thief ant having been found, for example, in an envelope, and again in a box of photo- graphic dry plates. The carpenter ant * (fig. 5) should be considered in the list of house ants, although perhaps only accidentally, and under exceptional cir- cumstances, a house-infesting species. The carpenter ant of North America, a subspecies or variety of the European and Asiatic 1 Prenolepis fulva Mayr subspecies pubens Forel, Neoponera villosa F. Smith, Cam- ponotus abdominalis Roger subspecies floridanus Buckley, and Pheidole flavens Roger sub- species floridanus Emery. 2 Solenopsis molesta Say. *It is further distinguished by the possession of very rudimentary eyes, and a two- jointed instead of three-jointed “ club” to the antenne. 4 Componotus herculeanus L., subspecies pennsylvanicus De G. 8 FARMERS’ BULLETIN 740. species of the same name, is dark brown or black in color, and is the largest of the house-frequenting ants, the workers varying from one-fourth to one-half inch in length and the winged female attain- ing a length of nearly an inch. It normally constructs its galleries in logs and dead trees in forests, but not infrequently, in the case of wooden houses, and especially those in or near forested tracts, gains access through porch beams or the underpinning of such houses and mines and weakens the supporting timbers and other woodwork. As a rule it affects only the decaying portions of the wood, but some- times carries its channels into the sound wood. Many instances of damage of this sort have been reported, possibly some of them, Fic. 5.—The carpenter ant (Camponotus herculeanus pennsylvanicus) : a, Winged female ; b, worker major; ¢, worker minor. All enlarged to same scale. (Original.) however, due to confusion of the work of this ant with that of the common termite or so-called white ant.* GARDEN AND LAWN ANTS AS HOUSE PESTS. Almost any of the common garden or lawn ants which build their little crater nests in lawns or in soil about houses may become tem- porarily or on occasion house pests in their search for food sub- stances. Four native ants and one introduced species have achieved notoriety in this way.? One of these, referred to in earlier cireu- lars issued by this department on house ants as the little black ant* 1 Leucotermes flavipes Kollar. 2 Monomorium minimum Buckley, Lasius niger L. var. americanus Emery, Prenolepis imparis Say, and Formica fusca L. var. subsericea Say. 3 Monomorium minimum Buckley. HOUSE ANTS: KINDS AND METHODS OF CONTROL. 9 (fig. 1), is essentially a lawn or meadow ant, and its entrance into houses is due to chance or accident. Its small nests, with the opening surrounded by its protecting wall of fine grains of soil, can be fre- quently noted in lawns, and if these nests are opened the colonies will be found to consist of workers, with one or more much larger gravid females. When these or other lawn ants gain access to houses, attracted by food supplies, the nuisance can often be eliminated by tracing them back to their outdoor colony and destroying the latter, as hereinafter described. Perhaps the most abundant and widespread lawn or garden ant is a small yellowish-brown species which may be given the common name of the American lawn ant. Its crater nests are exceptionally abundant throughout the Northern States, and not infrequently a dozen or more nests may occur on a square yard of lawn surface. In addition to the fact that it occasionally gains entrance to houses and becomes annoying as a depredator on larder supplies, it is a lawn and garden pest of some importance; and, furthermore, has the reputation of hoarding over winter the eggs of aphids and col- onizing the young aphids in the spring on their host plants, thus becoming a very important factor in increasing the damage to garden and field crops by these injurious insects. In the case of lawns and meadows, aside from the harboring of injurious aphids, direct injury from this ant is probably negligible, or is offset by the actual benefit which may result from the bringing up of its little cra- ters of sand and earth to form a sort of top dressing or soil mulch. The other two native garden and lawn ants have similar habits. In this same class of outdoor ants which may occasionally find entrance into houses. should be included the common European meadow ant,? one of the few Old-World ants of temperate regions which has been brought to America. This ant has readily accommo- dated itself to conditions of urban existence in the eastern United States, and its colonies occur in lawns and often under pavements, or beneath flagging or stones in yards. These colonies are often large and may frequently be uncovered in masses of a quart or more, on turning over stones in yards or lifting flagging in paths. HABITS AND LIFE HISTORY OF HOUSE ANTS. In habits and life history these ants are all much alike and, in common with other social insects, present that most complex and interesting phase of communal life, with its accompanying divi- sion of labor and diversity of forms of individuals, all working to- gether in the most perfect harmony and accord. The ants ordinarily- seen in houses are neuters or workers. In the colony itself, if it be dis- covered and opened, will be found also the larger wingless females and, 1 Lasius niger L. var. americanus Emery. 2Tetramorium caespitum L, 10 FARMERS’ BULLETIN 1740. at the proper season, the winged males and females. During most of the year, however, the colony consists almost exclusively of work- ers, with one or more perfect wingless females. Winged males and females are produced during the summer and almost immediately take their nuptial flight. The males soon perish, and the females shortly afterward tear off their own wings, which are but feebly attached, and set about the establishment of new colonies. The eggs, which are produced in extraordinary numbers by the females or “queen” ants, are very minute, oval, whitish objects, and are cared for by the workers, the young larvee being fed in very much the same way as in the colonies of the hive bee. The so-called ant eggs, in the popular conception, are not eggs at all, but the white larve and pupe, and those of females or males are much larger than those of the workers and many times larger than the true eggs. MEANS OF CONTROLLING HOUSE AND LAWN ANTS. DESTRUCTION OF HOUSE COLONIES. The distinctively house-inhabiting ants, such as the little red or Pharaoh’s ant, and other imported species nesting in the woodwork, masonry, or articles of furniture, etc., are often very difficult to eradicate because of their inaccessibility. If the nest can be located by following the workers back to their point of disappearance, the in- mates of the nest, if near by, may sometimes be reached by inject- ing a little bisulphid of carbon, kerosene, or gasoline into the open- ing by means of an oil can or small syringe. Jn the use of these substances, naturally, precautions should be taken to see that no fire is present, as all of them are inflammable. Tf the nest is under fioor- ing it may sometimes be gotten at by removing a section; but, as a rule, unless the colony can thus be reached and destroyed other meas- ures are of only temporary avail if food or other conditions continue to attract the ants and facilitate their continued breeding in the house. The removal, therefore, of the attracting substances in houses, wherever practical, should be the first step. Ants are attracted by food material, especially cake, bread, sugar, meat, and like sub- stances, in pantries and elsewhere, and the nuisance of their presence can be largely limited by promptly cleaning up all food scattered by children and by keeping in the pantry or storeroom all food supplies which may attract ants, in ant-proof metal containers or in ice boxes, and limiting the amount of such articles as far as possible to daily needs. That it is possible to drive ants away from household supplies by the use of repellents, particularly camphor and naphthalene flakes or powdered moth balls, has been asserted. The use of most of such repellent substances, however, in connection with food supplies, -is impracticable, and careful tests have indicated that such substances HOUSE ANTS: KINDS AND METHODS OF CONTROL. 11 have only slightly repellent properties and bring comparatively little benefit. The collection of ants by the use of attractive baits is frequently recommended. Perhaps as convenient a bait as any consists of small sponges moistened with sweetened water and placed in situations where they can be easily reached by the ants. These sponges may be collected several times daily and the ants swarming on them de- stroyed by immersion in hot water. It is reported also that a sirup made by dissolving borax and sugar in boiling water and distributed on sponges will effect the destruction of the ants in numbers. Reme- dies of this kind, however, are of doubtful value. They may be ‘useful at the outset when the colonies are few and small and when most of the individuals may, by these means, be secured and de- stroyed. Very frequently, however, the distribution of such baits will simply result in a more wide exploitation of a good forage ground and an actual increase of the ant nuisance. A more efficient remedy, where it can be safely used, is a sirup poisoned with arsenate of soda, the idea being that the ants will collect this poison sirup and convey it to their nests, so that not only the ants which collect the sirup are ultimately killed, but the inmates of nests feeding on it also succumb. The formula for the prepara- tion of this sirup is as follows: One pound of sugar dissolved in a quart of water, to which should be added 125 grains of arsenate of soda. The mixture should be boiled and strained, and on cooling is used with sponges, as already described. The addition of a small amount of honey is said to add to the attractiveness to ants of this mixture. Naturally the greatest precautions should be taken in preparing this sirup and in safeguarding it afterwards to prevent its being the cause of poisoning to human beings or domestic animals. This method of control has been tested for three years by an expert?! of the Bureau of Entomology of this department and has given very sat- isfactory results. Similar success with it has been reported by others, including persons engaged professionally in insect extermination. A related formula experimentally worked out for the Argentine ant will appear in a special bulletin on this insect.?_ This formula is as follows: Granulated (St gara seat pee} op | oath cone be lyerryes ehh - 15 pounds. Vivid? e222 et ee eo ee See, SORE Nee Yo Sere 7% pints. MaArtarieician (CeyStallized))) 2-2 ae a Sg + ounce. Boil these ingredients together slowly for 30 minutes and allow them to cool. Then slowly dissolve three-fourths ounce sodium arsenite (NaAsO.) in one-half pint of hot water. Allow this to cool, then add it to the sirup, stirring thor- roughly. Add 14 pounds of pure honey to the sirup and the mixture is ready for use. 1C. H. Popenoe. 4 Barber, EH. R. The Argentine ant: Distribution and control. U. 8. Dept. Agr. Bul. 377. 12 FARMERS’ BULLETIN 1740. DESTRUCTION OF LAWN ANTS. In the case of lawn ants where only a small area with few nests are concerned, drenching the nests with boiling water or injecting a small quantity of kerosene or coal oil will be effective, and similar treatment will apply to nests between or beneath paving stones. Another simple means of destroying such ants in lawns of small extent is to spray the lawns with kerosene emulsion (see Farmers’ Bulletin 127) or with a very strong soap wash, prepared by dissolv- ing any common laundry soap in water at the rate of from half a pound to a pound of soap to the gallon of water. An effective control method for larger ant colonies is to inject into the nest a quantity of bisulphide of carbon, a chemical which can be’ purchased at any drug store. This substance can be placed in the nest with an oil can, or small syringe, the quantity varying from half an ounce for a very tiny nest to 2 or 3 ounces or more, depending on the size of the nest. An oil can or syringe with a long spout is convenient for this purpose, as this can be inserted into the nests and the liquid injected without its being too near the operator’s nose. To facilitate entrance of the chemical, the ant hole can be enlarged with a sharp stick or iron rod. The depth of the injection will de- pend on the size of the nest—from an inch or two to greater depths. After injection of the bisulphide of carbon the entrance opening should be closed by pressure of the foot to retain the bisulphide, which will then penetrate slowly throughout the underground chan- nels of the nest and kill the inmates. The efliciency of this remedy is increased by covering the nest immediately after the injection with a wet blanket or other heavy cloth, to better retain the fumes of the chemical. Buisulphide of carbon has a very disagreeable odor, but its fumes are not poisonous to higher animals. As already noted, it should be kept away from fire, as its fumes are inflammable and may explode if ignited, much like gasoline vapor. PROTECTION FROM THE CARPENTER ANT. The method of protection from damage by the carpenter ant is practically the same as that employed to protect. from termites, namely, preventing the ants from gaining access to foundation tim- bers by using in the foundations only timbers which have been pre- viously impregnated with creosote. Ants infesting house timbers which have not been so protected may sometimes be reached and killed by the abundant use of kerosene injected by means of a syringe or, where the timbers are accessible, by spraying or soaking them with kerosene. All timbers which have been mined and weakened should, however, be replaced with timbers protected with creosote. 1A special publication on white ants (Department Bulletin No. 333, prepared in the Bureau of Entomology) has been issued by the Department of Agriculture and may be had on application. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1916 atee ite 35, Wy <8 ut mies ah yee 4 ae iP ONY Oe 1 A nig ‘see liin o ok - een ited har erty: +. ¢ ~ tiny “pl tf) g°tSe 7 éaniinns a } diate” on. a pebly wx qr . iS dnd Faye jb ate -_ ie . : =! Y ee. cate whirl ayy, : Gh O Gili hm af 2 Tees 7 = at ara pc nts ge a AL Sp LO al PR UNITED STATES DEPARTMENT OF AGRICULTURE FARMERS’ BULLETIN Wasuincton, D. C. TAl Juny 17, 1916 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE ALFALFA WEEVIL AND METHODS OF CON- TROLLING IT.’ By Geo. I. Reeves and Puiu B. Mites, Entomological Assistants, and THomaAs R. CHAMBERLIN, STERLING J. SNow, and LurHer J. Bower, Scientific Assistants, Cereal and Forage Insect Investigations. INTRODUCTION. The alfalfa weevil destroys a great deal of alfalfa in northern Utah and southern Idaho. It also inhabits southwestern Wyoming and is spreading slowly to new terri- tory im all directions. It may in time infest most of the United States. The adult (fig. 1), a small brown snout-beetle, and the larva (fig. 2), a green, worm- like creature, usually escape no- tice during the first two or three years that they are present in a locality, but as soon as they be- come numerous enough to do harm they are readily found, and their effect upon the appear- ance of the fields is conspicuous. Vigorous treatment is then nec- Fic. 1—The alfalfa weevil: Adult. Enlarged. essary to prevent partial or total * pole destruction of the first and second crops. The purpose of this bulletin is to show how serious the attack is to the farmer, how much territory it embraces and how it spreads, and to describe the insect, its work, and the methods which are effective in dealing with it. 1 Phytonomus posticus Gyll.; order Coleoptera, family Curculionidae. NotE.—This bulletin describes the work and spread of the most dreaded pest of alfalfa in the United States. It is of interest in the region west of the Mississippi River, particularly Utah and the adjacent States. 39320°—Bull. 741—16 1 9 FARMERS’ BULLETIN 741. IMPORTANCE OF THE ALFALFA WEEVIL AS A PEST. This insect attacks Utah’s most important crop. Alfalfa furnishes 80 per cent of the value of the hay and forage of the State, which in turn is 40 per cent of the value of all crops. The 1909 crop was worth nearly $6,000,000." About one-half of the annual yield is harvested in the first cutting and about one-third in the second. The damage to the first cutting ranges from slight depreciation of the quality of the hay to almost total loss, varying according to the rate of growth and the time of harvest; it may be estimated at 50 per cent. The damage to the second cutting, if no effort is made to prevent it, amounts to total loss. The menace to this State, there- fore, involves one-half the yield, worth $3,000,000. Besides the loss represented by these figures, there is a less tangible but equally serious effect due to the peculiar relation of alfalfa to western agriculture. Because of its ability to revive after prolonged drought, to produce abundant crops for many years Fic. 2.—The alfalfa weevil (Phytono- : : mus posticus): Larva. Much en- Without reseeding, and to furnish a nearly Ete neat) complete ration for live stock, it has a very great value for a region where the water supply is scanty, reseeding expensive and difficult, and live stock an important and increasing source of wealth. THE INFESTED DISTRICT. The infested district (fig. 3) reaches north from Salt Lake City to Rosette, Utah; Strevell, Malad City, and St. Charles, Idaho; and Cokeville and Granger, Wyo. It extends south to Moroni and Oasis, Utah. These points lie near the rim of a circle about 100 miles from Salt Lake City. Eastward the weevil has gone only about 50 miles to the Uinta Mountains and westward an equal distance to the Salt Lake Desert. SPREAD OF THE WEEVIL. Both the outline of the infested district and the history of the spread show an average seasonal advance of about 10 miles per year ‘since 1904 or 1905, when the insect was discovered by farmers at Salt Lake City. ‘There are no isolated colonies distant from the main body, and there have been no long jumps in the movement. If wagons and railroad trains have carried weevils it has evidently been only for short distances. As has been predicted,? their spread has been largely by crawling and flight. The greatest progress has been along 1 Thirteenth United States Census. 2 Utah Agricultural College Extension Department Bulletin No. 1, 1909. ALFALFA WEEVIL. o certain wagon roads, rather than in the direction of prevailing winds, railroads, or streams. This point is well illustrated by the road to St. Charles, Idaho. Here the insect has gone 100 miles along a main road, across mountain ranges, regardless of prevailing winds, and far from railroads. That no one knows exactly how the weevils spread, may be inferred from the conflicting quarantine regulations designed by uninfested >\SALTLLAKE CITY &) N} Ona t ies Su Y/fey Fic. 3.—Map of portions of Utah, Wyoming, and Idaho, showing the district infested by the alfalfa weevil. The circles are 50 and 100 miles from Salt Lake City. (Original.) States to exclude them. Thus, Arizona forbids the importation of nursery stock; California requires its fumigation at origin and delivery and forbids packing with hay, straw, or rushes; Idaho differs from California in permitting the use of rushes; Montana requires official fumigation at the point of origin; Oregon forbids the use of rushes and forage plants as packing; Arizona prohibits the importation of fruits; Montana, the importation of both fruits and vegetables from April 1 to October 31, except such as are inspected at designated points by the State of Utah from August 1 to October 31. Arizona and Oregon 4 FARMERS’ BULLETIN 1741. prohibit the entrance of alfalfa seed; California and Idaho require it to be fumigated by an official after arrival; and Montana requires it to be so fumigated before shipment. Hay and straw of all kinds are barred by all five States. Bees in hives are refused admittance by California and Idaho; and Oregon requires that they shall not be packed in rushes, weeds, or forage. Household goods must be inspected before shipment into Arizona. Live stock can be sbtpped into Arizona only with the consent of the State entomologist and must be transferred to clean cars before crossing the line. Califor- nia and Idaho prescribe that hay and straw must not be used in cattle cars, and Oregon forbids also grass and forage crops. Grain is barred from Arizona. Colorado, Wyoming, New Mexico, and Nevada have no restrictions on account of the alfalfa weevil. In spite of the contradictory popular ideas of the means by which the alfalfa weevil travels, many facts which bear upon the question are definitely known. Live weevils do not occur in alfalfa seed, either before or after it is recleaned. They are seldom found in nursery packing of any kind, fruits and vegetables, or hay and straw used for packing, bedding, or feed, except under the following con- ditions: They are often found in green alfalfa fresh from the fields and in second-crop hay and potatoes which have been handled in contact with it; and they are found also in cured alfalfa hay, espe- cially hay of the second cutting, in the stack, where some of them remain alive until the end of the following winter. They are found for several hours afterward in clothing which has been worn through infested fields in summer time, and sometimes remain even after the clothing has been packed in a trunk and shipped as baggage. The occurrence of weevils in green alfalfa hay and new hay of the second crop is particularly important, because potatoes which are to be shipped are often hauled to the car upon a bedding of it to prevent bruising and are sometimes covered with it to protect them from the sun. This hay usually contains weevils, which crawl from the alfalfa to the sacks and are loaded into the tight refrigerator car, in which they often remain until it reaches its destination. Although no colonies have yet been started by this means, there is constant danger of it, which can be minimized by simply keeping the hay away from ae potatoes. Another important consideration as to the occurrence of weevils in new hay is that many people driving through the country in summer carry it for short distances as feed for their horses. The weevils may leave the hay as a result of the jar of travel, according to their habit; and that they do so is the more probable because no colonies have been found at any distance from the main territory, as would have happened if they were carried long distances by wagon. There is, however, a constant stream of traffic over certain main roads, composed of sheepmen, peddlers, and others bent on a a ALFALFA WEEVIL. 5 business or social visits to other localities, near or remote. The carrying of weevils by these people, even if it be but for a mile or two, amounts in the aggregate to a systematic relaying of the species over through routes. There seems, in fact, to be a relation between the localities where alfalfa from infested fields is carried in this way and the country over which the weevils have spread most rapidly. No connection, can be traced between the railroads and the actual spread of the alfalfa weevil; in fact, the advance of the weevils has been rather less rapid along some railroads than in certain regions remote from them. The weevils occur rarely in baggage, express, and freight cars, and somewhat more often in passenger cars and refrigerator cars containing potatoes which have been handled with fresh second-crop alfalfa hay. Although there has been a large volume of unrestricted passenger traffic from the infested region during the past 12 years, no colonization of weevils has resulteds and although weevils have traveled in potato cars as far as Denver, Colo., Rock Springs, Wyo., and Butte, Mont., and many cars of potatoes which doubtless carried weevils were shipped throughout the Western States, no colonies have been started by this means. The transportation of weevils on railroad trains and wagons is little affected by the flying of the species. It seemed reasonable at an early period of the investigation to believe that a beetle which flies abroad in the summer would alight upon various commodities and vehicles and be carried for great distances, but such is not the fact. Weevils are rarely found on trains or wagons except in cases where new hay is involved.. The flight of the weevil not only plays a small part m its distribution by wagons and trains, but it is less general and extensive than it was once supposed to be. All records which are definite and authentic show only small numbers of the weevils in flight at any time. Reports dealing with immense num- bers swarming in the air usually mention no specimens at all as actually caught, identified, and counted. They do not agree with the observations of this bureau, and many of them are probably based, by mistake, upon some other insect, such as the dung-beetle, Aphodius, which resembles the weevil in appearance and is always present im the air in larger numbers than the latter. There is no evidence that the weevils ever fly for the purpose of seeking fields of alfalfa, either new or previously infested, or to find hibernation quarters. The most plausible theory is that their flight is caused by a rise in temperature, as are many activities of the lower animals. So far as can be learned, this flight is at random. It takes some of the weevils into new fields. The crawling of the larve is unimportant as a method of spread, being limited to a journey of a few feet from one field to another, but the crawling of the adults is an important matter. During the cold weather of spring and fall a day’s journey of an adult weevil is 6 FARMERS’ BULLETIN 1741. only a few inches, but during the warm months the adults crawl during the greater part of the day or, in July and August, of the night. Although they use up much of their energy in climbing up and down plants, and into and out of crevices in the ground, so that it is largely wasted so far as progress is concerned, a little of it happens to lead to new fields. There is no general movement by crawling, any more than by flight, from the fields to the ditch banks, fence rows, and similar places, or from such places to the fields, at any time. The crawling is most important, as has been shown, in bring- ing weevils into hay and so into traffic, which probably takes them somewhat far- ther than they could go without help. During the 12 years that the alfalfa wee- vil has been in Amer- ica it has spread into new territory very slowly and has agree- ably disappointed those who feared that it would extend rap- idly over all the alfalfa-producing re- gions of the conti- nent. Its progress is so slow that there is hope of providing control methods for new climates and conditions as fast as these are encoun- Fig. 4.—The alfalfa weevil: Work of the larvie. (Original. ) tered. Thereis hope also that the pest will not prove equally injurious under all cireum- stances. It is much less harmful in Europe than in America, owing apparently to climatic and industrial conditions, and it multiplies more slowly and does less damage in the higher altitudes in Utah and Wyoming than in the lower valleys, Nevertheless, it is possible that eventually every section of the country will have to consider, first, the problem of keeping the insect out of its boundaries, and later, the problem of growing alfalfa in spite of the weevil, or finding ALFALFA WEEVIL. zi a substitute for that valuable crop. It is therefore particularly de- sirable that farmers in the western mountains and plains should learn the appearance of the different stages of the weevil and be pre- pared to protect their crops. DESCRIPTION OF THE WEEVIL IN ITS DIFFERENT STAGES. THE FULL-GROWN LARVA. The insect is most easily discovered, during the early years of its presence in new fields, in the form of the full-grown larva (fig. 2). It is then a green wormlike creature one-fourth of an inch long, with a black head and a faint white stripe down the middle of the back, and it feeds upon the leaves of the alfalfa mainly during late May, June, and early July. It can be found by sweeping the tops of the plants with an insect net,.or by looking for the notches in the leaves where it has fed. When the larve are numerous they destroy most of the tender growth (fig. 4), causing the tops to appear white and making the field look at a distance as if frostbitten. THE NEWLY HATCHED LARV-®. The newly hatched larve are harder to find. They are only about one thirty-sec- ond of an inch long and remain hidden in the partly unfolded tips of the plants, ra. 5—1ne alfalfa weevil: Cocoon where they are not easily. seen of caught sttached to) dead) leaves Muth é 2 A enlarged. (Original.) by the net.- Their color is yellowish green, excepting the head, which is black. The color changes to green at the first molt, or shedding of the skin, and there is little change ex- cept in size during the two or three molts which follow, varying in number with the season of the year ia which the larval life is spent. THE PUPX AND COCOONS. The pupal form is the one in which the change from the larva to the adult takes place. The pupa is contained within a delicate, oval, netlike cocoon (fig. 5), woven of a few white threads and attached, sometimes to the lower part of a green stem, sometimes to rubbish on the ground, and often to the inner side of a curled dead leaf. The pupa within this cocoon is somewhat like the larva in color, but more like the adult beetle in form, becoming still more like it in both respects as it approaches maturity. THE ADULTS. The adult is harder to find than the larva, but is present m the field throughout the whole year instead of the summer only. It is an oval brown beetle, three-sixteenths of an inch long, with a promi- nent snout projecting downward from the front of the head. The 8 FARMERS’ BULLETIN 1741.’ color of old, weathered specimens is nearly black, owmg to the dark ground color revealed by the shedding of the brown, and yellow scales which at first clothe its upper surface. The adult stays close to the ground during early spring and late fall, but climbs about in the tops of the plants during the warm season. It is not readily seen by one walking through the fields, because it habitually drops to the ground when disturbed, and its color helps to make it invisible. It can be captured during the warm weather by sweeping the plants with a net and during the cooler spring and fall weather by sitting quietly in the field and catching it when it moves on the ground. In the winter it can be found by digging about the crowns and roots of alfalfa plants. THE EGGS. The eggs (fig. 6) are less conspicuous than the larve and adults, because they are usually con- cealed within the stems of the plants; but the holes in which they are placed are found in large numbers by examining the green stems during May and June, and in smaller numbers as early as March and as late as December. The eggs are small, oval, shiny globules, bright yellow when first laid, but dingy after a few days when incubation has begun, and adorned during the latter part of the incubation period with a black spot where the head of the little larva shows through the transparent shell. A few eggs, some of them infertile, are laid on the outside of the plants, and more in the weeds and grasses which grow in the field. Late in the fall and early in the spring there are many in the Fic. 6.—Thealfalfa weevil: dead stems on the ground. ne ga eae When an alfalfa grower outside the territory known. to be infested finds in his field any insect which he suspects to be a form of the alfalfa weevil, he should send it to the Bureau of Entomology field station at Salt Lake City, Utah, to be identified. If it proves to be the alfalfa weevil, it is important that work should begin without delay, so that the measures that will be effective in controlling the pest under the new conditions may be learned. This work requires study of the traveling, feeding, mating, and egg-laying habits of the insect; of the effect upon it of climate, crop conditions, and farm operations; and of the agricultural condi- tions of the region, in order that the conditions favoring the growth, increase, and work of the weevil and the conditions necessary to destroy it or hinder its work may be ascertained. So far as these things are already known in regard to the country now occupied by the weevil they are here set forth. ALFALFA WEEVIL. 9 HABITS OF THE WEEVIL. WHERE AND HOW THE WEEVILS PASS THE WINTER. When cold weather comes on the adult weevils creep down close to the ground and into crevices and spend the winter there. Some ditch banks and other uncultivated places which are strewn with the litter of dead vegetation harbor many of them, but these numbers are an insignificant part of those which remain in the fields and deposit eggs the following spring. Burning the grass and weeds in such places, therefore, while desirable in itself, gives practically no protection to the crop in neighboring fields. Many weevils die in the fields during zero weather, but milder winter temperatures seem to have little effect upon them. Since bare ground freezes more than that which is covered by snow, it is sometimes advisable to cultivate the field in the fall, so that the snow which falls upon it may melt and expose the weevils as much as possible to the cold. Owing to the fact that most-of the weevils spend the winter on the eround in the fields, it is possible to kill them by flooding the field with muddy water and thus covering it with sediment. There is no definite hibernation in this species. The adults are quiet when it is cold and active when it is warm. ae a eee 1 pound. VV SRG MAUEES 5 2 So es eee pees te hese ae 50 gallons. Never use white arsenic on plants, it will burn them. (6) An immense amount of good can be accomplished in destroy- ing these worms by the use of a poisoned bait which is scattered broadcast over the infested fields. Take 50 pounds of bran and mix with it either 1 pound of Paris green or 2 pounds of lead arsenate, then add 2 gallons of low-grade molasses and 6 finely chopped lemons. This is especially recommended for fields containing mixtures of grass and cowpeas, cowpeas and sorghum, or fields in which grass has been consumed by the caterpillars. Caution: Do not pasture stock in fields where the grass or other crops have been sprayed with a poison mixture until after heavy rains have fallen and not before three weeks after the application of the insecticides. WASHINGTON ; GOVERNMENT PRINTING OFFICE: 1916 UNITED STATES DEPARTMENT OF AGRICULTURE = (a FARMERW’ BULLETIN WasuincTon, D. C. TOA OcroBER 14, 1916 Contribution from the Bureau of Entomology, L. O. Howard, Chief. THE BEDBUG.' By C. L. Maruart, Entomologist and Assistant Chief of Burcau. CONTENTS. 3 Page. Page. Hn MPOCNEG ELON teres -sseeae eee ke 9 Genera lchoaractenisticS --2 ses.) ss 225 eee 3 | The bedbug and human diseases...........-- 9 Meee ire Py.a OC OR. seen = = = ase eee 4 | Natural enemies of the bedbug..-........... 10 Habits and life history.............-.--..--.- EN) ARG AGONRS G2 se oBoosene oe ae be cnc sae Se ceaeoee 11 INTRODUCTION. The presence of the bedbug (fig. 1) in a house is not necessarily an indication of neglect or carelessness; for, little as the idea may be relished, this insect may gain access in spite of the adoption of all reasonable precautions. It is very apt to get into the trunks and satchels of travelers, or into baskets of laundry, and may thus be introduced into homes. Unfortunately, also, it is quite capable of migrating from one house to another and will often continue to come from an adjoining house, sometimes for a period of several months, gaining entrance daily. Such migration is especially likely to take place if the human inhabitants of an infested house leave it. With the failure of their usual source of food, the migratory instinct of the bedbugs is developed, and, escaping through win- dows, they pass along walls, water pipes, or gutters, and thus gain entrance into adjoiming houses. In these or other ways anyone’s premises may be temporarily invaded. 1 Cimex lectularius L.; order Hemiptera, suborder Heteroptera, family Cimicidae. 48406°—Bull. 754—16 9 FARMERS’ BULLETIN 754. _ ORIGIN; COMMON NAMES; DISTRIBUTION. As with nearly all the insects associated with man, the bedbug has had the habits now characteristic of it as far back as the records run. It was undoubtedly of common occurrence in the dwellings of the ancient peoples of Asia. The Romans were well acquainted with it, giving it.the name Cimex. It was supposed by Pliny—and this was doubtless the common belief among the Romans—to have medicinal Sede and it was recommended, among other things, as a specific for the bites of serpents. It is said to have been first introduced into England in 1503, but the references to it are of such a nature as to make it very probable that it had been there long before. Two hundred and fifty years later it was reported to be very abundant in the seaport towns, but was scarcely known inland. Fia. 1.—Bedbug ( Cimezx lectularius): a, Adult female, engorged with blood; b, same from below; c, rudimen- tary wing pad; d, mouth parts. a,b, Much enlarged; c, d, highly magnified. (Author’s illustration.) One of the old English names was ‘‘wall-louse.”’ It was after- ward very well known as the ‘‘chinch,’’ which continued to be the common appellation for it until within a century or two, and is still used in parts of this country. The origin of the name ‘‘bedbug”’ is not known, but it is such a descriptive one that it would seem to have been very naturally suggested. Almost everywhere there are local names for these parasites, as, for illustration, around Boston they are called ‘‘chintzes’”? and ‘‘chinches,’”’ and from Baltimore comes the name ‘‘mahogany flat,’? while in New York they are styled ‘‘red coats,’’ and in the west ‘‘crimson ramblers.”’ The bedbug has accompanied man wherever he has gone. Ships are very apt to be infested with it and have been the chief means of its wide distribution. It probably came to this country with the earliest colonists; at least Kalm, writing in 1748-49, stated that it was plentiful in the English colonies and in Canada, though unknown among the Indians. THE BEDBUG. 3 VARIETIES AND RELATED INSECTS. What may eventually prove to be mere variations of the ordinary type of human bedbug have been described as distinct species in sev- eral instances. For example, the common bedbug of southern Asia is supposed to present some slight variations from the European type, chiefly in being somewhat more elongate. These slightly diverging forms of the bedbug in different parts of the world, which are not known to have any special bird or animal host other than human beings, may prove to be merely local races or varieties of the ordinary bedbug. . Birds, bats, and poultry are attacked in various parts of the world by a considerable number of parasitic bugs, closely related to the bedbug, which live on their hosts and in nests and about roosting places. One of these species, occurring abundantly in southwestern United States and Mexico,' probably originally a parasitic messmate on birds and bats, has come to be an unmitigated poultry pest, and from the close association in these regions between poultry and human beings, is often a serious house pest—more so even than the true bed- bug. Others of the species infesting birds and bats may also on occa- sion become house pests. For example, the nests of the common barn or eaves swallow of this country often swarm with the barn- swallow bug,? and from such nests under the eaves of dwelling houses these bugs sometimes gain entrance to houses and beds and are the cause of much annoyance. Similarly a species,? normally a parasite of birds and bats in the Old World, and also in Brazil and the West Indies, not infrequently becomes a human parasite. GENERAL CHARACTERISTICS. The bedbug belongs to the order Hemiptera, which includes the true bugs or piercing insects, characterized by possessing a piercing and sucking beak. The bedbug is to man what the chinch bug is to grains or the squash bug to cucurbs. Like nearly all the insects parasitic on animals, however, it is degraded structurally, its para- sitic nature and the slight necessity for extensive locomotion having resulted, after many ages doubtless, in the loss of wings and the assumption of a comparatively simple structure. Before feeding, the adult (fig. 2) is much flattened, oval, and in color is rust red, with the abdomen more or less tinged with black. When engorged the body becomes much bloated and elongated and brightly colored from the ingested blood. The wings are represented by the merest rudiments, barely recognizable pads, and the simple eyes or ocelli 1( Cimer) Haematosiphon inodora Dugés. 2( Cimer) Oeciacus hirundinis Jenyns. 3 Cimczr hemipterus Fab. (synonym, rotundatus Sign.). 4 FARMERS’ BULLETIN 154. of most other true bugs are lacking. The absence of wings is a most fortunate circumstance, since otherwise there would be no safety from it even for the most careful of housekeepers. Some slight vari- ation in length of wing pads has been observed, but none with wings showing any considerable development has ever been found. THE “BUGGY” ODOR. The most characteristic feature of the bedbug is the very distinct and disagreeable odor which it exhales, an odor well known to all who have been familiar with it as the ‘‘buggy”’ odor. This odor is by no means limited to the bedbug, but is characteristic of most plant bugs also. The common chinch bug affecting small grains and the squash bugs all possess this odor, and it is quite as pungent with these plant-feeding forms as with the human parasite. The possession of this odor, disagreeable as it is, is very fortunate after all, as it is of considerable assistance in detecting the presence of these vermin, The odor comes from glands, situated in various parts of the body, which se- crete a clear, oily, volatile liquid. With the plant-feeding forms this odor is cer- tainly a means of protection against in- sectivorous birds, rendering these in- sects obnoxious or distasteful to their feathered enemies. With the bedbug, on the other hand, it is probably an Fig. 2.—Bedbug: Adult before engorge- llustration of a very common phenom- ae Rae ie: (Author’sillus- enon among animals, i. e., the persist- ence of a characteristic which is no, longer of any especial value to the possessor. The natural ene- mies of true bugs, against which this odor serves as a means of pro- tection, in the conditions under which the bedbug lives, are kept away from it; and the roach, which sometimes feeds on bedbugs, is evidently not deterred by the odor, while the common house ant and the house centipede, which may also attack the bedbug, seem not to find this odor disagreeable. HABITS AND LIFE HISTORY. The bedbug is normally nocturnal in habits and displays a certain degree of wariness, caution, and intelligence in its efforts at conceal- ment during the day. Under the stress of hunger, however, it will emerge from its place of concealment in a well-lighted room at night, so that under such circumstances keeping the gas or electric light burning is not a complete protection. It has been known under similar conditions to attack human beings voraciously in broad : THE BEDBUG. 5 daylight. It usually leaves its victim as soon as it has become engorged with blood and retires to its normal place of concealment, either in cracks in the bedstead, especially if the latter be one of the wooden variety, or behind wainscoting, or under loose wall paper, and in these and similar places it manifests its gregarious habit by collecting in masses. It thrives particularly in filthy apartments and in old houses which are full of cracks and crevices, in which it can conceal itself beyond easyreach. As justnoted the old-fashioned, heavy, wooden-slatted bedsteads afford especially favorable situa- tions for the concealment and multiplication of this insect, and the general use in later years of iron and brass bedsteads has very greatly facilitated its eradication. Such beds, however, do not insure safety, as the insects are able to find places of concealment even about such beds, or get to them readily from their other hiding places. Extraordinary stories are current of the remarkable intelligence of this insect in circumventing various efforts to prevent its gaining access to beds. Most of these are undoubtedly exaggerations, but the inherited experience of many centuries of companionship with man, during which the bedbug has always found its host an active enemy, has resulted in a knowledge of the habits of the human animal and a facility of concealment, particularly as evidenced by its abandoning beds and often going to distant quarters for protec- tion and hiding during daylight, which indicate considerable apparent intelligence. Like its allies, the bedbug undergoes what is known as an incom- plete metamorphosis. In other words, the insect from its larval to its adult stage is active and similar in form, structure, and habit, contrasting with flies and moths in their very diverse life stages of larva, chrysalis, or pupa, and winged adult. The eggs (fig. 3,d) are white oval objects having a little projecting rim around one edge and may be found in batches of from 6 to 50 in cracks and crevices where the parent bugs go for concealment. In confinement eggs may be deposited almost daily over a period of two months or more and commonly at the rate of from one to five eggs per day, but sometimes much larger batches are laid. As many as 190 eggs have been thus obtained from a single captured female. The eggs hatch in a week or 10 days in the hot weather of mid- summer, but cold may lengthen or even double this egg period or check development altogether. The young escape by pushing up the lid-like top with its projecting rim. When first emerged (fig. 3, a, b) they are yellowish white and nearly transparent, the brown color of the more mature insect increasing with the later molts (fig. 4). 1 Girault, A. A. Preliminary studies on the biology cf the bedbug, Cimex lectularius, Linn. IIT. Facts obtained concerning the habits of the adult. Jn Jour. Econ. Biol., v. 9, no. 1, p. 25-45. 1914, 6 FARMERS’ BULLETIN 754. During the course of its development the bedbug molts or sheds its skin normally five times, and with the last molt the minute wing pads, characteristic of the adult insect, make their appearance. A period of about 11 weeks was formerly supposed to be necessary for the complete maturity of the insect, but breeding experiments with Fic. 3.—Bedbug: Egg and newly hatched larva: a, Larva from below; }, larva from above; c, claw; d,egg; c, hair or spine oflarva. Greatly enlarged, natural size of larva and egg indicated by hair lines. (Author’s illustration.) this insect, conducted in this department in 1896, indicated that the life cycle is subject to great variation, being entirely dependent on warmth and food supply. Under favorable conditions of temper- ature and food it was found that there was an average period of about eight days between moltings and between the laying of eggs and their hatching, giving about seven weeks as the period under these fic. 4.—Bedbug: a, Larval skin shed at first molt; b, second larval stage immediately after emerging from a; c, same after first meal, distended with blood. Greatly enlarged. (Author’s illustration.) conditions from egg to adult insect. The molting periods are shorter in the earlier stages and lengthen in the later stages. There are many exceptions, however, and some individuals even under the same conditions remain two or three weeks without molting. Under con- ditions of famine, or without food, as already shown, the bedbug may remain unchanged in any of the immature stages for an indefinite ~~ THE BEDBUG. it time, and the checking of development by such starvation may result in additional molting periods. The breeding records referred to, and numerous confirmatory experiments subsequently made by other investigators, indicate that ordinarily but one meal is taken between molts, so that each bedbug must puncture its host five times before becoming mature, and at least once afterwards before it can develop eggs. Additional meals between molts may be taken under favoring circumstances, however, and particularly when the insect has been disturbed and has not become fully engorged at its first meal after a molting or other period. The bedbug takes from 5 to 10 minutes to become bloated with blood, and then retires to its place of concealment for 6 to 10 days for the quiet digestion of its enormous meal, and for subsequent molting, or reproduction if in the adult stage. Such feeding and reproduction may, under favorable conditions of temperature, continue throughout the year, and in one instance the progeny of a captured female adult was carried through three con- tinuous generations.' Unfavorable conditions of temperature and food will necessarily result in great variation in the number of generations annually and in the rate of multiplication, but allowing for reasonable checks on development, there may be at least four successive broods in a year in houses kept well heated in winter. FOOD AND LONGEVITY. Under normal conditions the food of the common bedbug is obtained from human beings only, and no other unforced feeding habit has been reported. It is easily possible, however, to force the bedbug to feed on mice, rats, birds, etc., and probably it may do so occasionally in nature in the absence of its normal host. The abundance of this insect in houses which have long been untenanted may occasionally be accounted for by such other sources of food, but probably normally such infestation can be explained by the natural longevity of the insect and its ability to survive for practically a year, and perhaps more, without food. There are many records indicating the ability of the bedbug to survive for long periods without food, and specimens have been kept for a year in a sealed vial with absolutely no means of sustenance whatever. In the course of the department’s study of this insect in 1896, young bedbugs, obtained from eggs, were kept in small sealed vials for several months, remaining active in spite of the fact that they had never taken any nourishment whatever.