194 



APPLIED ENTOMOLOGY 



it greatly resembles a tiny cicada. The insects pass the winter as adults hiding 

 in crevices of the bark or similar protected places and in spring lay their eggs 

 on the twigs, and particularly around the bases of the buds. These eggs hatch 

 in from 2 to 3 weeks according to the temperature. The nymphs (Fig. 

 185) suck the sap from the axils of the leaves and fruit stems and if abundant 

 gather around the bases of leaves and fruit stems and spread to the under surface 

 of the leaves themselves. They move about but little and secrete large amounts 

 of honey-dew, sometimes so much when they are very numerous, as to cover 

 the leaves and branches. They are broadly oval, flat creatures, yellowish at 

 first but blackish with reddish marks later and with bright red eyes. They 

 become adult in about a month and lay their eggs, this time on the under side 

 of the leaves or on the leaf petioles. These eggs hatch in a week to 10 days and 

 adults are produced in about a month. There are three or four generations a 

 year in New England and more in the South. 



FIG. 184. FIG. 185. 



FIG. 184. Adult Pear Psylla (Psyllia pyricola Forst.) about ten times natural size. 

 (From Britton, Third Rept. Ent. Conn. Agr. Exp. Sta. 1903, after Slingerland.) 



FIG. 185. Nymph of Pear Psylla, greatly enlarged. (From Britton, Third Rept. Ent. 

 Conn. Agr. Exp. Sta. 1903, after Slingerland.) 



Control. Methods for checking the injuries caused by these insects center 

 around their control in winter and early spring. Most of the adults winter 

 under the loose bark of the trees or in tufts of grass and rubbish near the trees. 

 Scraping off all loose bark and removal of the rubbish, followed during any 

 warm days in November or December by a thorough spraying of these places 

 with nicotine sulfate, standard formula, will kill large numbers. It should not 

 be cold enough for the spray to freeze on the trees. In spring, just as the clusters 

 of blossom buds begin to separate from each other, but before the blossoms 

 open, the lime-sulfur wash diluted at the rate of 1 part of the wash to 8 or 9 

 parts of water will kill the eggs and any newly-hatched nymphs. The fruit 

 spurs and the under sides of the twigs should receive particular attention with 

 this treatment. 



Family Aphididae (Plant Lice or Aphids). This is one of the most 

 important groups of insects from an economic standpoint, as all its mem- 

 bers are injurious, often very abundant, and a species usually doing little 

 harm may at any time become a serious pest. 



