Observations on the Life Histories of Some Leafhoppers (Homoptera: Cicadellidae) Occurring on Apple Trees, and Their Control with Insecticides

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Abstract
Accounts are given of the life histories of six species of leafhoppers of the subfamily Typhlocybinae found breeding on apple trees at East Mailing in each of the years 1956 to 1959. Erythroneura alneti (Dahlb.) and Typhlocyba froggatii Baker were the most abundant, Typhlocyba rosae (L.) and Erythroneura flammigera (Geoffr.) occurred in smaller numbers, and populations of Empoasca flavescens (Fabr.) and Typhlocyba quervus (Fabr.) were so low that little information on their life cycles was obtained. E. alneti and T. froggatti overwinter as eggs and are uni- and bivoltine respectively. T. rosae overwinters in the egg stage and is bivoltine ; apple is a host of the second generation but not, apparently, of the first, which occurs on Rosa and other hosts. E. flammigera overwinters as an adult on evergreen plants ; it is usually univoltine, but the evidence suggests that a partial second generation occurred in 1956. The effects on nymphal populations of various insecticides applied primarily for control of codling moth, Cydia pomonella (L.), were determined. The materials were applied in late June, when nymphal populations of E. alneti and T. froggatti were at or near their peak levels, and again in mid- or late July, when second generation nymphs of T. froggatti and T. rosae were beginning to hatch. Treatments of o∙1% carbaryl, 0∙04% azinphos-methyl, o∙6% ryania, and 0∙1% DDT emulsion gave excellent control for the remainder of the season ; unlike the emulsion, o∙1% DDT wettable powder did not entirely prevent the development of populations of second generation T. froggatti and T. rosae ; 0∙02% diazinon was effective against young nymphs for only two weeks ; 0∙2% lead arsenate had little or no effect on nymphal populations in 1956 and 1957, but some reduction was observed in 1958.

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