g- Pie 5 Biological 7 ff, oe & Medical S . University of Maine enals oY - os a ue ROVAL-CANADIAN te ESTITUTE Bo, ee 2 Mi Avricultural Expert rie et Staion BULLETIN 267 NOVEMBER, 1917 ———— THE APHID OF CHOKE CHERRY AND GRAIN. CONTENTS ; PAGE Description of Spring Generations on Choke Cherry........... 293 Weseummmon, of Grain Generations. 295 Summer Food Plants... On "Ve ae 295 7, (OS So SEO SL eo 295 SATE oo MS hc: ee See a 295 ree Grrr DINOS cOl Wimmer Fig. 32 MAINE AGRICULTURAL EXPERIMENT STATION ORONO, MAINE. THE STATION COUNCIL. PRESIDENT ROBERT J. ALEY, President DIRECTOR CHARLES D. WOODS, Secretary FREELAND JONES, Bangor, } : THOMAS V. DOHERTY, Houlton, Committee of FRANK E. GUERNSEY, Dover, __| Board: of Tee JOHN A. ROBERTS, Commissioner of Agriculture EUGENE H. LIBBY, Auburn, State Grange WILSON W. CONANT, Buckfild, State Pomological Society FRANK S. ADAMS, Bowdoinham, State Dairymen’s Association LEONARD C. HOLSTON, Cornish, Maine Livestock Breeders’ Ass'n. WILLIAM G. HUNTON, Readfield, Maine Seed Improvement Ass'n. AND THE HEADS AND ASSOCIATES OF STATION DEPARTMENTS, AND THE DEAN OF THE COLLEGE OF AGRICULTURE. THE STATION STAFE. \ CHARLES D. WOODS, Sc D. Director ADMINIS- _) \WARIAN AVERY Clerk TRATION | ESTELLE M. GOGGIN Stenographer RAYMOND PEARL, Pu. D., Biologist* FRANK M. SURFACE, Pu. D., Biologist* JOHN W. GOWEN, Pu. D., Assistant BIOLOGY SILVIA PARKER, A. B., Assistant JOHN R. MINER, A. B., Computer* MILDRED R. COVELL, Clerk HELEN A. RING, Laboratory Assistant | ween M.. BARTLETT, M: S;, Chemist ede = HERMAN. H. HANSON, M. S., Chemist LHEMISTERY 4 -HAROLD. 1 omING Bas: Assistant Pee J. SHATNEY, Laboratory Assistant ENTOMOL- ( EDITH M. PATCH, Pa. D., Entomologist OGY ) ALICE W. AVERILL, Laboratory Assistant WARNER J. MORSE, Pu. D., Pathologist PLANT | aticHaeL SHAPOVALOV, M. S., Assistant PATHOLOGY ) +GLEN B. RAMSEY, A. M., Assistant | VIOLA L. MORRIS, Laboratory Assistant : ue JACOB ZINN, Aer. D., Assistant Biologist poe LOU ) Cc HARRY WHITE, Scientific Aid FARM} JEREMIAH ‘E. SULLIVAN, Superintendent HIGHMOOR ( WELLINGTON SINCLAIR, Superintendent FARM }) WALTER E. CURTIS, Scientific Aid ROYDEN L. HAMMOND, Seed Analyst and Photographer CHARLES C. INMAN, Assistant * Absent on leave during period of war. + In collaboration with U. S, Department of Agriculture, BULLETIN 267 THE APHID OF CHOKE CHERRY AND GRAIN.! Aphis pseudoavenae sp. n. EpitH M. Patcu. Late in June, 1917, a group of choke cherries on the campus of the University of Maine were found to be heavily infested with a species of aphid which I had not previously taken, although specimens of the same thing were brought me from Fort Kent, Maine, July 6, 1916 where they were found by Professor C. L. Metcalf while collecting syrphids. Mounted specimens of this aphid would be most likely to be determined as Aphis avenae (i. e. of American authors) because of the constriction before the flange of the cornicle, the arrangement of the sensoria of the antennae, and the rather long, pointed stigma and the noticeably short second branch of M in the wing. However, the fresh colonies crowded close along the stem and ventral leaf would suggest at once the Aphis rumicis group on acount of the conspicuous areas of wax powder, and could not be mistaken for avenae in life. DESCRIPTION FROM LIFE. SPRING CHOKE CHERRY GENERATIONS. Apterous viviparous female: A rather old individual had body dark olive green irregularly mottled with still darker. Areas of powder especially noticeable in lateral rows of spots on abdomen, one on each side of segments just dorsad of promi- nent lateral crease, and over the tip of the abdomen caudad cornicles. These white areas are conspicuous on undisturbed colony but the powder is soon shaken off from collected material and then the aphids show only a general rather slight pulverul- ‘Papers from the Maine Agricultural Experiment Station: Entomol- ogy No. 95. 294 Maine AGRICULTURAL EXPERIMENT STATION. 1917. ency. There is a deep purplish area (internal) at the base of each cornicle. Tibiae and base of antennae pale, cauda and cornicles black. Cornicles with constriction before flange with perhaps a suggestion of constriction at middle. Beak short, scarcely reaching second coxae. Alate viviparous female: Head and thoracic lobes glis- tening black, general body color dark olive green. Breastplate, anal plate, cauda and cornicles black. Cornicles constricted before flange and tendency toward a very slight midconstriction. There are three large, heavy, black spots along lateral line of abdomen cephalad the cornicles, and an irregular black patch at base of cornicle, caudad. The second branch of M is typically near margin of the wing, though there is considerable variation in the length of this branch. The shape and length of stigma is variable but it is always pointed and rather elongate. The rela- tive length of the antennal segments and the number of sensoria are also unstable factors. The drawings show what is a good average. Sensoria are always present on III (25 more or less), and IV (10 more or less) and usually on V (a few). The beak reaches about half way between first and second coxae. Spring nymph developing to alate female: The newly dropped or newly molted nymph is yellowish or pale brown, with rusty area (internal) at base of cornicle. The nymph soon colors to dark olive green. INSTAR ANTENNA BEAK Ist. 4-segmented just caudad 3rd coxae 2nd. 5-segmented reaches 3rd coxae 3rd. 6-segmented 2nd coxae or beyond 4th. (pupae) 6-segmented not reaching 2nd coxae. In the pupal instar this nymph is dark olive green, with five lateral powder spots on each side of abdomen cephalad cornicles and a solid powder area caudad the cornicles. Powder spots are present on base of head and on prothorax. There is a dark rusty area at base of cornicle due to internal substance showing through the body wall. Cauda is pale at base with black tip, and the cornicles are black. Tue Apuip or CHOKE CHERRY AND GRAIN 295 GRAIN GENERATIONS. Apterous viviparous female. Unlike their choke cherry pro- genitors, the summer colonies do not share pulverulency in any instar. In general body color they are soft dark green, dull amber greenish, to very pale greenish; always unmarked by any darker green streaks and always with strong rusty space at base of cornicles and often connecting them, a color being due to internal structure showing through the body wall. Alate viviparous female. The laboratory bred specimens had olive green abdomens with black lateral spots, a black patch at caudal base of cornicle and some black median dashes caudad the cornicles. SuMMER Foop PLANTS. Migration tests were made by placing the winged June forms on various grasses. The progency of the migrants accepted the following: Timothy, Kentucky bluegrass, sheep fesque, meadow fesque, red top, barley and oats. The test was continued through one generation only, except with the oats which was used during the summer for the material under observation. eine ACVCLE No data are yet available for the stem female as the first choke cherry collection was made June 25. At this time both apterous and alate viviparous females were present, the latter being recently developed as was evidenced by the abundance of individuals in the pupal instar. The migrants were already taking wing on June 25th and the process continued for a week or so longer. No collections were taken in the field in the summer here but in the laboratory material continued to live on oats until about the first of September, the colony dying out at that time partly from unknown causes. Discussion OF NAME. Whatever the ultimate fate of the name proposed for this species may be, there seems to be no safely established American 296 Maine AGRICULTURAL EXPERIMENT STATION. 1917. aphid to which to refer it. It is not the avenae of American authors which has well defined characteristic dark green longi- tudinal streaks entirely absent in pseudoavenae. It is not the avenae of Theobald (Canadian Entomologist, 1916 p. 235). It is not the padi described and figured by Koch and Buckton. Is it the padi of Van der Goot (1915 p. 241)? Possibly, “in part”, though it is certainly not in accord with his collection from Mespilus and Pirus malus. No such aphid has previously been recorded on its spring host in this country as it is none of the species listed from choke cherry. That it has been taken on grain and confused with the apple grain aphid, the so called “avenae” of American authors seems not improbable as these two species are so much alike in structural characters that they would be distinguished with diff- culty from mounted material. In life, however, they are readily separable especially in the spring generations with a simple hand lens, the characteristic dark green longitudinal lines of our so called “avenae’ being entirely absent from all generations of pseudoavenae and the powder areas of the spring generations of pseudoavenae being particularly noticeable. Both species have a rusty internal area near the bases of the cornicles. 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