REPORT OF THE Department of Entomology. P. J. PARROTT, Entomologist. HUGH GLASGOW, Associate Entomologist. TABLE OF CONTENTS. I. Plant lice injurious to apple orchards. II. The radish maggot. III. The cherry leaf-beetle. REPORT OF THE DEPARTMENT OF ENTOMOLOGY. PLANT LICE INJURIOUS TO APPLE STUDIES ON CONTROL OF NEWLY-HATCHED P. J. PARROTT, H. E. HODGKISS AND F. H. LATHROP. SUMMARY. This is the second report of life history studies and experiments with the apple aphides (Aphis sorbi, avene and pomi), which have for their object the establishment of efficient spraying practices for the protection of bearing apple orchards. The newly-hatched nymphs of the three species are tiny insects which are quite similar in general appearance and habits. They are readily separated by structural differences, principally of antennæ and cornicles. Descriptions are given of first instar nymphs and adults of first generation in which recognition characters are clearly indicated. In general, infestation of orchards in western New York during 1916 was not severe. At the outset the oat aphis outnumbered the rosy aphis and the green aphis in most orchards, altho their comparative numbers varied locally. The relative abundance of the three species exhibits a seasonal succession or cycle which, while probably varying somewhat from year to year, appears to be fundamentally constant. At Geneva activities began with the hatching of goodly numbers of the oat aphis on April 22. A few rosy aphides were detected on the buds at the same date, but this species did not reach maximum numbers until four days later. The green aphis was the last species to hatch and began to emerge on April 26. As during the preceding year, dwarfing of apples was chiefly the work of the rosy aphis; altho losses in fruit yields in this respect were rarely of serious extent. In experiments with the aphides all species attacked succulent tissues, as blossom and fruit stems, tender leaves and young apples. * Reprint of Bulletin No. 431, March, 1917. |