s 353.9 E3R 1916 NO. 13 1 MONTANA Agricultural College Experiment Station F. B. LIN FIELD, Director HLLLF/nX NO. 109 Thirteenth Annual Report of the State Entomologist of Montana The Cottonwood Leaf Beetle, Una scripta Fab. BY R. A. COOLEY BOZEMAN, MONTANA FEBRUARY. 1916 SMPOBLICmsCOLLEC™ OCT 3 12007 . MONTANA STATE LIBRARY 1515 E. 6th AVE HELENA, MONTANA 5^620 Montana Agricultural College Experiment Station BOZEMAN, MONTANA Helera Great Falls Missoula Billings Bozeman Helena Butte Dillon Libbv Bozeman Bozeman Bozeman Bo.'^eiiiaii STATE BOARD OF EDUCATION SAMUEL V. STEWART, Governor ) J. B. POINDEXTEH, Attorney General [ Ex-Officio H. A. DAVEE, Sup't Public Instruction ) 8. D. LARGENT ....... C. H. HALL ....... WARD H. NYE ....... W. S. HARTMAN ...... JOHN DIETRICH ...... J. BRUCE KREMER ...... A. L. STONE ....... LEO EAUST EXECUTIVE BOARD JAMES M. HAMILTON, President J. H. BAKER, Vice-President . . . . • W. S. DAVIDSON ....... GEORGE R. CALLAWAY, Secretary and Treasurer STATION STAFF F. B. LINFTELD. B. S. A., Director R. A. COOLEY, B. Sc, Entomologist ALFRED ATKINSON, M. S., Agronomist C. N. ARNETT, B. S., Animal Husbandman EDMUND BURKE, B. S., Chemist and Meteorologist DEANE B. SWINGLE, U. S., Botanist and Bacteriologist O. B. WHIPPLE, B. S., Horticulturist HOWARD WELCH, D. V. M., Veterinarian WM. P. SCHOPPE, M. S., Poultryman H. E. IMURDOCK, C. E., M. E., Agricultural Engineer E. L. CURRIER, B. Sc, Farm Management J. B. NELSON, Assist. Agronomist REUBEN M. PINCKNEY, B. S., A. M., Assist. Chemist L. F. GIESEKER, M. S. A., Assist. Agronomist H. E. MORRIS, B. S., Assist. Botanist and Bacteriologist J. R. PARKER, B. Sc, Assist. Entomologist G. E. SMITH, B. A. Sc, Assist. Chemist B. W. WHITLOCK, B. S., Superintendent Grain Laboratory E. J. QUINN, B. S., Assist. Chemist R. R. DODDERIDGE, B. S., Assist. Animal Husbandman C. C. STARRING, B. S., Assist. Horticulturist R. S. JONES. B. S., Assist. Chemist OSCAR TRETSVEN, Assist. Animal Husbandman D. C. WOOD, B. S., Assist. Farm Management E. W. JAHNKE, B. S., Assist. Grain Laboratory NOTICE. — The Bulletins of the Experiment Station will be mailed free to any citizen of Montana on request. Please state whether all the publications are desired as issued or only those specified. Give name and address plainly. All communications to the Experiment Station should be addressed to THE MONTANA EXPERIMENT STATION, Bozeman Montana Montana State Library 3 0864 1004 0621 7 Thirteenth Annual Report of the State Entomolocjist of Montana INSECT PESTS OF 1915 The amount of damage caused b}' insects in Montana durini; the season of 1915 was greater than in any other year since the office of state entomologist was created. The outstanding feature of the year was tlie abundance of grain pests, the worst of wliich was the army cutworm. This insect aL>ne destroyed at least 10i.),0tH) acres of grain. The more imjiortant insects which came to our notice during the year are brieHy discussed and recorded. ACARINa Leaf Blister Mite {Ki-iophyes ])i/ri Pgst). For several years the leaf blister mite has been increasingly injurious in the apple orchards of the Bitter Root X'alley and during the past season it is reported to have done more damage than any other orchard pest. Clover Mite {Bryohia prafensis Garman). Several letters were recei\ed complaining that this mite was inxading houses. In one instance it was reported as injuring clover lawns. Red Spider {Teti-anyclnis hiniacitlatus Harvey). In the \-icinity of Flathead Lake red spiders were unusually injurious to raspberries. Spotted Fever Tick ( Derm acev for reiuisfris Iianks). One of the striking- features of the season of 1915 was the appearance of this tick in large numbers in eastern Montana where it previouslv had attracted but little attention. A number of cases of spotted fever were also reported for the first time from this locality. ORTHOPTERA Grasshoppers (.Icridldae). Not a single report of grasshopper injury was received during the season, which is rather remarkable considering the abundance of insects in general. Coulee Cricket (Peranahnis scahracollis Thom.). This large, clumsy cricket, which attracted much attention in Washington during the past summer, also appeared in western Montana on the Flathead Reservation. In several places it caused considerable injury. HEMIPTERA Capsid injury to wheat {Capsus ater Linn). An unusual injury 152 MONTANA EXPERIMENT STATION to winter wheat was reported from Plains in April. An examination disclosed numerous black capsids sucking the juice from the plants, which became spotted at the point of attack. But little loss resulted from the attack. Green Apple Aphis (Jpliis jx/mi l)e G.). Present in about normal numbers. Cabbage Aphis {tJphis hrassicae L.). Not as injurious as in 1914. Grain Root Aphis [Fordti occiilenfalis). This plant louse occurs very commonly upon the roots of wheat and is often blamed for the injury caused by Ih-aclnjcohts tritici. In no instance has Fordo, l)een observed to seriously injure its host plant. Western Grain Aphis [llnichijcolns tritici Gillette). This aphid which has l^een increasing and spreading in Alontana for several years was highly injurious to winter wheat, in some instances com- pletely destroying entire fields. Considerable time was spent in studying this important pest and its life history and a method of control have been worked out. Absolutely clean summer fallow is a sure preventive of injury. Aphids in heads of grain. During August daily reports were received of aphids infesting heads of grain. Generally the specimens sent in were badly mashed and accurate determination was not always possible. Genera recognized were .Ifarrosiplunn , To.voptera and Apltis. Little damage was done as the grain was well advanced when the insects first appeared in numbers. Sugar Beet Root Louse ( I'rmplii'Jiifi hetae Doane). Investiga- tions concerning this important sugar beet pest were carried on under the Adams fund as in previous years. It is hoped that a system of irrigation may be worked out which will reduce injury from this insect to a minimum. Woolly Aphis (Srliizoneiira lanigera Hanseman). In the Bitter Root \ alley this insect appears to be spreading and becoming more firmly established each year. LEPIDOPTERA Army Cutworm {Clioriza gratis auxiliaris Grote). !Many sec- tions of the State were devastated bv armies of cutworms belonging for the most part to the above named species. This was by far the THIRTEEXTH AXXUAL REPORT OF STATE EXTOMOLOGIST lo3 most destructive insect of tlie ycai- and is nKire fully discussed else- where in this report. Mourning Cloak Butterfly ( Kiivanessa antlopa L.j. The spiny caterpillars of this species were abundant in many parts of the State and were frequently sent in with the report that they were feeding^ on elm and willow foliai^e. Noctuid working' in Cottonwood bark { I'orosn e received into our collection. Bumble Flower Beetle (Kiiplioria iiula L.). In the Yellowstone \'alley this beetle was again reported as injuring ctjrn l)y working in the kernels at the tip of the ear. False Wireworm (Eleodes e.rfricata var. rojircvim/ lis Idaisdell). False wireworms were very abundant in many localities and in several instances were injurious to newly sprouted grain. Cottonwood Leaf Beetle (Liiui scripta Fab.). During July and August this was the insect concerning whicli there was the greatest demand for information. Cottonwood and willow trees were attacked in all |)arts of the Stale. AA'hile this pest seldom kills trees outright, it causes the foliage to turn l:)rown and greatly weakens the ^•itality of the tree. A drawing of the adult beetle ap]:)ears on tlie cover of this pul:)lication. Dung Beetle (,l])ha(/iifs iju/jiinafv.^ Abst.). I'or the past two seasons tliis insect has ap])eared in enormous numl)ers and has attracted much attention. In tlie fall on warm, still days the air frequently appears filled with the adults, and horse droppings are com])lelely worked over in a few minutes. Wireworms (Ehiteri(hie). Numerous reports of wireworm iiijury were received during the course of the year, including injury to potatoes, corn and grain. THIRTEENTH ANNUAL REPORT OF STATE ENTOMOLOGIST 155 Some of tlie Principal State Interests in Entomology in 1915 THE ARMY CUTWORM The uutstandin<>- feature of tlie vear in .Mciiiana from the stand- point of the entomologist was an unprecedented outbreak of the army cutworm (CJiorizagTotis (in.vi /i'u-is). On April 'i we received a report of the presence of this insect in eastern ]^lontana and after this many other reports came in from other parts of the State in rapid succession. The outbreak was quite general and severe. While some cutworms were reported from western Montana practically all of the damage was done east of the divide. This insect is a very general feeder and refuses almost no plants that come in its way, yet practicall\- all >7 history. Accordingly certain experiments and studies were under- taken under the Federal Adams fund, which have resulted in gather- ing facts of the greatest importance. These will he prepared for publication during the winter. THE ALFALFA WEEVIL General interest has continued in the effort to prevent the intm- duction of the alfalfa weevil into Montana from Utah. Idaho, and Wyoming where it now exists. Several reports of the weevil in Montana have been looked up. but in no instance have we found this insect, excepting in shipments coming from Utah. The work of the lesser clover weevil (PJn/fononnis nigrirostria) closelv resem- bles that of the alfalfa wce\il and the larvae of the two insects are very much alike. A destructive colony of the lesser clover weevil appeared in the western part of the State this }ear and there is small wonder that farmers were alarmed. Every effort is being made to keep the alfalfa \vee\il I'Ut of Montana. If it should be introduced and if it should be as injurious here as it is in Utah, where it is continuing to be \ery destructive year after year, it would lie a very serious tiling for Montana where the alfalfa crop takes such a ])rominent ])Iace in the agriculture of the State. Until further information is received, at least, it will be the policy of this office to recommend maintaining a reasona1)le quar- antine in order that the chances of introducing this insect may be reduced to a minimum. THE WESTERN WHEAT APHIS The outbreak of army cutworms and the ne\vsi)a])cr comments upon it in various parts of the State directed unusual attention to other ]:)ests of wheat. Farmers in looking for cutworms found other insects and wrote us aliout tliem. Some of these are (if considera1:)le importance. A number of rc])orts of damage 1)_\- tlie western wheat aphis, lii-iicJij/m/ IIS tiHici. were received. Ihis insect was first brought to our attention sexeral years ago and as i)ractically nothing was known regarding its life-liistory and the means of controlling it we ha\e given sjiecial attention to it. Wheat i)lants aff'ected by the wheat a])liis have a characteristic a])])earance \\hicli is easily recognized wlien once seen. Voung infested plants show a thick- loS MONTANA EXPERIMENT STATION ening- and l)roadening- of tlie leaf blades. A very few aphids on a plant may have a surprisingly injurious effect. Some plants show in the later stages of injury a characteristic twisting of the stem and a deformed head. The injury often appears only in spots in the held, but sometimes entire fields are affected and much damase results. The only literature on the life-history and control has been issued by this office. \\'e have been able to recommend an effective method of control and we feel that when grain growers become familiar with the insect and the wav to control it the damase will be much reduced. One important scientific paper on this subject has been pub- lished during the year* and it is intended to print and distribute a l>ulletin during the coming vear. A NEW CUTWORM A little known cutworm (Ei(.xoa neai qnadTidentata) was brought to our attention by Senator T. O. Larson of Choteau who reported damage to wheat near Brady in Teton County. A con- siderable number of acres of grain had been severely damaged and some alarm was felt in the neighborhood. This insect was studied in the insectary where valuable information was received and it will be given further attention as Ave have opportunity. It is not prol)able that it will be found to be nearly so important a pest as the army cutworm. THE WHEAT STEM MAGGOT Farmers in western Montana reported a peculiar injury to grain in ]\lay. Injured plants when examined were f(^und to contain small, white maggots in the axis. These turned out to l)e the voung of the wheat stem maggot. Ccrodmifha fciiioi-dHs. These maggots bore down through the stem, completely destroying tlie plant, and go out through the crown into the earth Avhere they pupate. The eggs are laid on the leaves l)v the parent fiies whicli are \-erv small and not easil}- found. The li\ing insects were studied in the insectary and the stages of (le\elopment were worked out. It is hoped that further study may devise a method of controlling this little known ]:)est. * Parker, J. R. The western -uheat aphis. In Journal of Eoouomie Entomology, Vol. 9, No. ], 1916. THIKTEEXTH ANNUAL EEPOKT OF STATE ENTOMOLOGIST 15t» Along with this insect we ftHi.ul also sheath maggots (Afrininiizd aineTicana and ,1/. ni ^riventris) which were cluing some damage, but less than the stem maggots. A study (jf these maggots will be continued. THE SPOTTED FEVER TICK In tlie Twelfth Annual Repi.rt of the State ICntonMliigist a brief review^ of the status and organization of the work