53.9 3R 919 NO. 17 University ok Montana Agricultural Experiment Station BOZEMAN, MONTANA BULLETIN NO. 133 DECEMBER, 1919 Seventeenth Annual Report of the State Entomologist of Montana The Alfalfa Weevil, a serious pest of alfalfa, which has spread northward from Utah until it has now appeared on the Montana boundary in Idaho. BY R. A. COOLEY m?mimmK:i OCT 3 1 2007 MONTANA STAlrUBRARv Montana State Library 3 0864 1004 0521 9 Seventeenth Annual Report of the State Entomologist of Montana INSECT PESTS OF 1919. THE MITES AND TICKS (ACARINA). Red Spider {Tetranychus birnaculatus Harvey). There was the usual number of reports of injury from this pest to raspberry and currant bushes. Beans in eastern Montana suffered somewhat from red spider attack. Pear-Leaf Blister Mite {Eriophyes pyri Pagnat). In general the fruit crop of the Bitter Root Valley suffered less injury from this pest during the past year than for several years previously. GRICKETS AND GRASSHOPPERS (ORTHOPTERA). Black Cricket {Gryllus assimilis Stew.). This common black cricket was again present in Big Horn county. It was also reported injurious in Rosebud and Yellowstone counties where it was com- bated with poisoned bran mash the same as used for grasshoppers. The best results wxre obtained when the arsenical content was increased somewhat over the standard amount. Warrior or Yellow-Winged Grasshopper {Camnula pellucida Scudd.). In ten counties of the state this grasshopper occurred in enormous numbers and during the latter part of the summer the State Entomologist's forces gave their entire time to aiding farmers to save their grain fields from this insect. Lack of sufficient money for traveling prevented a greater service to the state. Big-Headed Grasshopper {Aidocara elliotti Thom.). In recent years the big-headed grasshopper has not caused much difficulty, but during 1919 it was encountered in great numbers in Gallatin, Beaverhead, and Madison counties, where it was doing damage to grasses. 4 MONTANA EXPERIMENT STATION Bui. 133 THE TRUE BUGS, PLANT LICE, ETC. (HEMIPTERA). Box Elder Bug (Leptocoris trivittatus Say.). This insect ordin- arily confines itself to the box elder but was reported to have injured fruit in the vicinity of Joliet. Cottony Maple Leaf-Scale {Pulvinaria acericola Walsh & Riley). This louse has been known to be present on shade trees in the cities of Missoula and Kalispell for some years but during the present season there was a great increase and injury was reported. Bedbugs {Cimex lectularius Linn.). More than the normal number of requests for advice on "how to rid the house of bugs," came to us this season. The cyanide fumigation method, although it necessitates some danger and expense, is recommended and ex- cellent results have been obtained. Chinch Bug {Blissus lencojjterus Say.). The country south of Glasgow where chinch bugs were abundant in 1911 was examined thoroughh^ again this season but no evidence of a reoccurrence of tlie pest could be found. Cabbage Louse {Aphis hvassicae Linn.). The cabbage louse was observed to be much more abundant than for some time past. Inquiries were numerous as to how this insect could be destroyed. False Chinch Bug (Xysius ericae Schill). On account of being mistaken for the real chinch bug (Blissiis lencopterus Say.) this insect causes alarm wherever found. Although it is a bad pest in gardens, in no way does it approach its eastern relative in the amount of destruction which it can cause. Oyster Shell Bark Louse (Lepidosa plies uhni Linn.). The oyster shell scale was present in less than normal numbers in the Bitter Root Valley in 1919. Sugar-Beet Root-Louse {Pejnphi^ns hetae Doane). This was more abundant than it has been since 1916 and damage was done in the beet-growing districts of the state. MOTHS AND BUTTERFLIES (LEPIDOPTEEA). Imported Cabbage Worm (Pontia rapac Linn.). This caused an increased loss to the cabbage crop. Many calls for information on control methods were received and it is safe to say that this insect has not been so plentiful for several years past. Corn Ear Worm (Heliothis obsoleta Fab.). This insect is becom- ing more important among the pests of eastern ]\'Iontana and this SEVENTEENTH ANNUAL REPORT OF STATE ENTOMOLOGIST 5 year was especially abundant. The first generation of worms attacks corn when only a few inches high while a later generation gnaws out the kernels at the tips of the ears. Mourning Cloak Butterfly (Euvanessa antiopa Linn.). The larvae of this species, known as the "spiny elm caterpillar," eat the foliage of elm, willow, and cottonwood. Specimens were received from several localities where they were reported numerous. Cecropia Moth (Samia cecTopia Linn.). This large moth and caterpillar, often mistaken for the silkworm, was abundant at Glas- gow, Union, and Sidney. Cutworms {Xoctiddae). Cutworms were as abundant as usual in gardens all over the state. Almost every kind of garden plant was attacked. In some places onions suffered severely from being chewed off near the surface of the soil. Pale Western Cutworm {Porosagrotis orthogonia Morr.). Throughout twelve counties in the northern and eastern sections of the state, as well as in two counties of the central district, this insect caused enormous losses to the grain crop. In many cases what the worms partially destroyed the drought finished, but in as many other instances partial loss from drought was made com- plete by the ravages of the worms. This is a new pest in Montana and can not be combated by the ordinary methods employed against cutworms. Parnassius Butterfly {Farnassiiis smintheiis D. & H.). This beautiful butterfly was abundant in the mountainous sections of the state during a short period last summer. Tent Caterpillar (Cliswcainpa sp.). In some sections of north- ern and eastern Montana the wild rose foliage was completely destroyed before July 1 by this insect. Currant bushes, not protected with sprays, also suffered injury. The Oblique-Banded Leaf- Roller {Arcliip rosaceana Harris). This year saw an increase of this insect in the Bitter Root Valley and a considerable amount of damage was done to the foliage of apple trees. Mediterranean Flour Moth (Epliestis kuehniella Zell.). This insect is regarded as the most important of all pests which infest flour mills, warehouses, grain mills, and stores. The larvae feed upon all kinds of grain products. The fine wel) which they spin G MONTANA EXPERIMENT STATION Bui. 133 causes a clogging of machinery besides their being the cause of introduction of filth into the materials. Fumigation, intense heat, or intense cold, are the remedies employed. Sugar Beet Webworm {Loxoste§e sticticalis L.). Primarily a pest of sugar beets, this insect is also the cause of much injury to gardens and alfalfa in nearly all parts of the state. A slight decrease in its occurrence was noted this season. The destruction of thistle, which farmers in the northern part of the state wished to harvest for stock feed on account of drought conditions, has been a bad factor with this pest. Codling Moth {Cydia -pomoneUa Linn.). This well-known pest of the apple, formerly present only in the vicinity of Missoula, is becoming more widespread in the Bitter Root Valley. Elsewhere it is by all odds the worst insect enemy which apple growers have to fight and its establishment here will make necessary on the part of the orchardists more effort toward insect control. FLIES (DIPTEEA). Wheat Stem Maggot {Hyleinyia cerealis Gillette). This mag- got, which bores through the central stems of wheat, was present again this season. The field in Yellowstone county, where the pest was first discovered in this state, was again a complete loss. Drought and cutworms in the northern part of Montana caused maggot injury to be largely overlooked. Onion Maggot (Phorhia ceparinn ]\Ieade). A slight decrease in the presenec of this insect was noticeable this year although in some localities considerable loss from it was incurred. Cabbage Maggot (Phorhia hrassicae Boche). Xo injury from this pest was reported this season. Currant Fruit Fly {EpocTira canadensis Leow.). A normal amount of damage to currants and gooseberries from this insect, which in some places has caused the growing of these crops to be abandoned, was reported to the State Entomologist. House Fly (.Musca domestical . House f^ies were exceptionally abundant during the past season and were the source of much annoy- ance, not to speak of their activity in the spreading of disease. THE BEETLES (COLEOPTERA). The Common Meal Worm {TeneTyrio molitor Linn.). The ■'Cadelle" {Tenehrioides mauritanicus Linn.). These well known SEVENTEENTH ANNUAL REPORT OF STATE ENTOMOLOGIST 7 insects cf flour mills were reported from Great Falls. Losses due to these insects are largely preventable by fumigation. Flea Beetles {Epitri.x sp.). Flea beetles, attacking potatoes, inmatoes, and all kinds of garden plants just as they were coming out of the ground early in the season, were the source of much trouble and numerous complaints concerning them came to our atten- tion from all parts of the state. Cottonwood Blotch Miner {Odontota sp.). In many parts of Montana the cottonwood trees were severely injured by this insect which works between the surfaces of the leaves. On account of its mode of attack it can not be destroyed by ordinary spraying, and as its life-history is not thoroughly known other means which might prove effective for destroying it have not been found. June Beetles {Lachnosterna sp.). These large beetles, the par- ents of white grubs, were observed in greater abundance than in former years. Colorado Potato Beetle (Leptinotarsa decemlineata Say). Potato beetles were present in usual abundance. This is one of the few insects about which it may be said that methods of control are almost universally known. Paris green is the standard remedy but it is being replaced to a large extent by a cheaper arsenical, arsenite of zinc, which has been recommended during the past three years by the State Entomologist. Wireworms {Elateridae) . Wireworms again occupied their place of importance among the grain pests of the state. Numerous inquiries were received as to what they were and how they could be destroyed. Confused Flour Beetle {TrihoJUnyv confiisium Duv.). A per- sistent pest of stored cereals, crushed feed, and other starchy food, was found in the feed bins of the poultry department of the Montana Experiment Station. Alfalfa Weevil {Phytonomiis posticus Gyll.). During the latter part of August a trip was made by automobile along the Oregon Short Line Railway from Dillon to Monida and through the Cen- tennial Valley in an effort to determine if the alfalfa weevil was spreading into Montana. Careful search of alfalfa fields revealed no evidence of the pest in this territory, which is the most exposed of any part of Montana to migrations of this insect from infested regions of Idaho and Utah. S MONTANA EXPERIMENT STATION Bui. 133 CURRENT ENTOMOLOGICAL PROBLEMS Some of the outstanding entomological problems of the present time are the following: PALE WESTERN CUT^VOR^[ For several years we have been giving attention to cutworms in garden and tield crops in Montana and gradually information of considerable value is being brought together. It is evident that there is a considerable variety of very destructive cutworms in the state, though in any one year the trouble is caused mainly by some one or another single species. The species which is best known in Montana is undoubtedly the army cutworm {Choriza§rotis aux- iliaris Grote) which at times has caused extensive damage to fall wheat, but during the past few years there has appeared another which is quite as serious. This is the pale western cutworm {PoTosa^votis orfJio^onia ^Morr.") which has been mentioned in previous reports, but which we are, year by year, recognizing as more serious than we had suspected. Without much doubt over a million dollars' worth of grain was destro^-ed in Montana in 1919. Similar extensive damage occurred in Canada, just north of Montana, in the same year. There appear to be four reasons why this is an unusually injurious cutworm. (1) It has a long period of larval feeding extending from the middle of April for upward of two months. In this it contrasts strongly with the army cutworm which, wlien abundant, attracts attention in April and is all through feeding by May 10, or about a month in all. (2) Its damage is done so late in the season that it is too late to put in a crop of spring grain, as can l)e done sometimes when the grain has been eaten off by the army cutworm. (3) The pale western cutworm feeds under ground and we know of no practical way to kill it. Poisoned bran mash scattered thinly over the surface, so effective in controlling the army cutworm, does not atfect this species. (4") It is not heavily attacked by parasites and continues year after year, gradually becom- ing more abundant and destructive. This cutworm has already become a serious problem in Montana and is receiving careful atten- tion from this office. Under our Experiment Station research funds we are studying its habits and control. Excellent progress has been made and we have much information of value but no satisfactory rcmedv has vet been worked out. SEVENTEENTH ANNUAL REPORT OF STATE ENTOMOLOGIST & GRASSHOPPERS The state collection of insects contains upward of one hundred species of Montana grasshoppers. With so many in the state it is not strange that one or another of them becomes abundant and injurious occasionally. In 1919 grasshoppers were more than usually injurious. Early in the season in May, reports began to reach the of^ce of a species w^hich was appearing in alarming num- bers in the far eastern part of the state. Specimens accompanying inquiries turned out to be Eritetix tricamanata. Mr. Strand went to the locality where this grasshopper was injurious in Tune and advised with the farmers on its control. Later in the season, the warrior grasshopper {Cannula pel- lucida) appeared in great numbers in most parts of the state. Our notes show it to have been present in great numbers in Gallatin, Missoula, and Beaverhead counties. In some localities this grass- hopper was present in enormous numbers, migrating more or less in the air and congregating in the foothills around the valleys for egg-laying purposes, where the ground was literally covered with these insects busily engaged in boring into the earth and depositing their pods of eggs. There can be little doubt that some trouble will be experienced in 1920 from the grasshoppers originating from these eggs unless steps are taken to destroy either the eggs or the young grasshoppers soon after hatching. While on a trip of searching for the alfalfa weevil in the counties of Gallatin, Beaverhead, and ]\Iad- ison, Mr. Parker and Mr. Strand encountered large numbers of the same species which was very abundant in Montana sixteen years ago, namely, the big-headed grasshopper (AuJocara elliotti Thomas). This is a true grass-feeding species and its occurrence in large numbers is always important. It is one of Montana's worst insect enemies to range grass. In earlier years I have seen the range completely bared of grass by this species. It is a remarkable thing that grasshoppers of the Melanoplus atlanis group which were very abundant and destructive in diflferent parts of Montana as recently as 1918, and especially one year earlier, were not abundant in the state in any place so far as we know in 1919. In 1917 and 1918 when Melanoplus w^as abundant we observed that wherever these insects were numerous, parasitic flies were also present in great numbers. We believe that tliese flies ]0 MU^■ TANA EXPERI:u:ENT STATION Bui. 133 were the cause of the disappearance of the grasshopper. It is noted now that these parasitic flies are not present in connection with the outbreaks of the three grasshoppers listed above as injurious in 1919. \\'e look upon this as indicating that the grasshopper diffi- culty will be continued through several years. SUGAR-BEET WEBWORM The common name, sugar-beet webworm, is not a satisfactory one for the insect (Lo.rostege sticticalis Linn.) w^hich in recent years has been unusually abundant and has caused general apprehension among farmers and gardeners. During the season of 1919 this insect occurred in large numbers, though probably not quite as abundantly as during the preceding year, and was the occasion of a considerable amount of correspondence aii-ing over the central and northern portions of Montana. There were two broods, the first appearing in May and early June and the second mainly in August. The injury done w^as chiefly to garden plants and to the Russian thistle. The presence of large numbers of this insect in grain fields, feeding on the Russian thistle, caused the farmers to become anxious in many cases and they wrote to us for information regarding what might be expected. It was feared that they w^ould attack the grain when the Russian thistles were all gone. Experience has indicated that this w^ebworm does not attack wheat and w^e were able to assure the farmers that no damage would be done. In some cases farmers were afraid to plant a new crop of grain because they knew that this insect was still in the soil from the preceding year, appearing there as larvae in long silken tubes, ver- tically placed in the soil. A number of letters were wn-itten to such farmers. Real injury, however, was done in gardens where beets, spinach, and a few other plants were eaten. This insect is capable of doing extensive damage in sugar beet fields. ALFALFA The alfalfa weevil (Phytonomus posticus Gyll.), which attracted the attention of the residents of Utah in the year 1901 and has spread and caused extensive loss to growlers of alfalfa and stockmen in that state, has continued to spread to the northward. This very injurious insect has in a relatively brief time extended into parts of three states by direct spreading and during the same time has made two jumps, one "into Colorado and another into western Idaho, SEVENTEENTH ANNUAL KEPOKT UF STATE ENTuMOLO'ilST 11 and is continuing- to extend itself. According to information recently secured from the Bureau of Entomology office at Salt Lake the following counties in Idaho now have the weevil : Madison, Fremont, Bonneville, Bingham, Bannock, Bear Lake, Franklin, Oneida, Power, Cassia, Ada, Payette, Canyon, and Washington. One of these coun- ties, Fremont, is the first county over the boundary from Montana. The weevil has been spreading perhaps fifty miles a year and with- out much doubt during the next year or two will be found to occur in Montana. It takes several years after being introduced for this insect to multiply in sufficient numbers to do real damage or to become sufficiently numerous to be discovered. It may be, tlierefore, that this insect already occurs undetected in Beaverhead, Madison or Gallatin County. The quarantine which we now have in force is effective only against the transportation of the weevil by rai^ Such transportation would lead to its establishment in more or less remote localities, while by spreading overland it gradually spreads across the country. AVith the coming of this insect into Montana we will be con- fronted by an entirely new and a very serious condition. This insect is primarilv injurious to alfalfa and seriously reduces the tonnage, making it necessary to do a large amount of work in order to pro- duce a profitable crop of hay. It is also of much importance to stockmen who are vitally interested in the alfalfa crop and the prices which they must pay. The coming of this insect into Montana will, therefore, be looked upon eventually as a serious matter. The state of Idaho has recently removed the quarantine between the counties that are infested and those that are not in the state, thereby making it possible to move hay without restriction in that state. For this reason it will be necessary for Montana to establish a quarantine against the whole of Idaho in order that our own inter- ests may be protected. FOUL BEOOD OF BEES Our first knowledge of the presence of American foul brood of bees in Montana came in the spring of 1911 when a sample of this disease was sent in from Joliet. In the report of the State Ento- mologist for 1911 a recommendation was made that a law be passed providing for inspection and control. The nature of the legislation needed was pointed out in the ninth report. In the tenth report, 12 MONTANA EXPERIMENT STATION Bui. 133 one 3'ear later, the subject was again briefly discussed, pointing out the situation and obvious needs. In nearly every report since that time we have called attention to the progress that the disease is making in its spread over the state, to the seriousness of the situation in the bee industry, and to the legislation needed. Nothing has been done. Meantime, American foul brood disease has spread extensively and has entered practically every important honey-producing section of the state. Many beekeepers have been put out of business . Aban- doned colonies of bees containing infectious material have been left where the bees died, continuing to spread the malady. Representatives of the State Beekeepers Association called upon the State Entomologist in their official capacity in December, 1919. asking that this ofifice cooperate with them in an effort to draw up a suitable law and once more make an effort to have it passed by the legislature. Accordingly, we are engaged in a review of the various bee laws in the United States and intend to have a bill ready before the next meeting of the legislature which shall have the combined support of the beekeepers of the state and of the State Entomologist. THE CODLING MOTH (CAEPOCAPSA POMONELLA LINN.) The codling moth, the general insect enemy of the apple, has been present in Montana for at least twenty-five years, although isolated and confined largely to some of the older towns in which large apple trees are growing. Considerable attention was given to its habits and control in earlier years and various publications have been issued from this office. With the growth of the orchards in the fruit-growing sections and the development of the orchard industry, this insect has come into more prominence in recent years, due to the increase in its numbers under favorable conditions found on the larger trees. Fruit growers in western Montana have recently brought to the attention of this office the fact that the codling moth occurs in injurious numbers and that it is necessary to adopt ener- getic means of control. During the past year we received also letters from other parts of the state asking for assistance. We believe that the reason for the greater interest in this subject in 1919 was due to the unusually w^arm season. The weather dried off and became hot early in the year and made it possible for a destructive SEVENTEENTH ANNUAL EEPORT OF STATE ENTOMOLOGIST 13 second brood of the moth to develop. I do not expect that in other years the codling moth will be as serious in Montana as in some other states because of the natural limitations placed upon a second brood. It will, however, be sufficiently abundant to cause loss to fruit growers and energetic measures should be adopted to hold it in control. Fruit growlers who have codling moth should spray for it. Most fruit growlers have more than one insect pest or fungous disease and all should adopt a spraying program which should be consistently carried out year after year. LEAF-EOLLER OF THE APPLE Our attention has been called to the leaf-roller which appeared in injurious numbers on apple trees in the Bitter Root Valley in 3 919. In some instances large numbers of trees w^ere more or less completely denuded. It is impossible for us to say at the present time which one of two species is the cause of the trouble. The fruit-tree leaf-roller {Archi-ps argyrospUa \\''alker) is sometimes spoken of as the Colorado leaf-roller and growers locally have spoken of this as being that insect. However, in past years we have in a number of instances reared the oblique-banded leaf-roller (Aj'cJiips rosaceana Harris) from the Bitter Root Valley. In some instances this latter insect has done rather serious damage to a limited number of trees. We shall have to wait for further developments of next season before we can determine which of these species is present. Satisfactory results in control can be secured by the use of miscible oils applied as a spray in the spring as soon as the weather warms up sufficiently to make spraying operations possible. It is not believed that this will be a pest which will continue year after year. Its history has been that it has occurred intermittently. FLEA BEETLES The season of 1919 was notable for the number of flea beetles which occurred. These minute beetles, with swollen hind legs enabling them to jump away when disturbed, are present more or less generally in small numbers each year but in the past season they occurred in such numbers as to cause rather extensive damage in gardens, on tomato and potato plants, and in sugar-beets. These insects work early in the season, destroying young plants soon after they come out of the soil. The stand in sugar-beet fields is some- times seriouslv reduced bv great numbers of flea beetles completely :i MONTANA EXPERIMENT STATION Bui. 133 destroying- a large proportion of the seedlings. The following species were sent in during 1919 or have been collected in earlier years: Epitrix siihcTuiita , Phyllotreta albionica, Phyllotreta pusilla, Psylliodes punctulata, Crepidodera lielxines. Epitrix sudcrinita was the species most injurious during the past season. SERIOUS LACK OF FUNDS. Requests for information concerning insects and aid in con- trolling them have increased to such an extent that a full time assistant is now employed the year around. During the summer months this assistant goes about the state demonstrating methods of control and organizing control campaigns in counties where serious insect outbreaks occur. The services of this assistant are in constant demand throughout the summer and many thousands of dollars have been saved to the farmers of the state as a result of his work. During the winter months talks are given at farmers' meetings and at county agent conferences. Considerable time is also given to preparing information on insect control, making por- table exhibits of insect life history, and developing the collection of state insects. The total appropriation for the work of the State Entomologist is now only $3300 a year. The salary of the assistant entomologist is $2000, leaving only $1300 for traveling expenses, student labor, scientific journals and supplies. During the past summer the demand for aid in controlling grasshoppers was so great that our funds for traveling expenses were exhausted by midsummer and many requests for aid were refused because we had no means of getting about the state. The condition was so serious that a request for funds was made to the special session of the legislature. A bill carrying an appropriation of $5000 was introduced by Senator Featherly and was passed by the Senate. The bill was not approved by the House Appropriation Committee and was consequently killed. If this money had been provided thousands of dollars" worth of crops could have been saved last summer, and by scouting during the fall breeding grounds could have been located and the eggs or young 'hoppers destroyed. As the situation now stands we are facing what promises to be one of the worst grasshopper years in the historv of the state, we are threatened with an invasion of the SEVEXTEEXTH ANNUAL REPORT OF STATE ENTOMOLOGIST 15 alfalfa weevil, wliich is even now almost to our state line, and our working funds are not sufficient to carry out the routine work of an average year. Unless the State Entomologist's appropriation is materially increased, we will not be able to render the service expected from this office by the farmers of the state. Ji