. Manual of fruit insects. FiG. 153. —Aphid eggs on apple twig. Fig. 154. —Apple leaf aphis on quince. 142 APPLE INSECTS 143. ously injured, the leaves being badly curled and the growth ofthe tree checked. The aphids secrete a sweet liquid known ashoney-dew in which a black fungus de-velops and gives the infested foliage andtwigs a sooty appearance. In large, bear-ing apple orchards, these plant-lice some-times appear in incredible numbers andnot only curl and kill some of the ter-minal leaves but attack the young fruits,preventing their full development andgiving them a knotty, stunted appear
. Manual of fruit insects. FiG. 153. —Aphid eggs on apple twig. Fig. 154. —Apple leaf aphis on quince. 142 APPLE INSECTS 143. ously injured, the leaves being badly curled and the growth ofthe tree checked. The aphids secrete a sweet liquid known ashoney-dew in which a black fungus de-velops and gives the infested foliage andtwigs a sooty appearance. In large, bear-ing apple orchards, these plant-lice some-times appear in incredible numbers andnot only curl and kill some of the ter-minal leaves but attack the young fruits,preventing their full development andgiving them a knotty, stunted appear-ance (Figs. 157, 158 and 159). The threespecies of these aphids now common onapple trees throughout the United Statesare Aphis pomi, Aphis sorhi and Sipho-coryne avence. The interesting and somewhat compli-cated life histories of these plant-lice havenot been fully worked out. The last twospecies breed on the apple trees for only a few generations inthe spring and early summer, then migrate to other food-plants,but return to the trees in the fall, where the hibernating eggsare laid. The first species remains on the tre
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbenefic, bookyear1915
