258 STATE HORTICULTURAL SOCIETY. 



to measure an inch. They are elongate pyriform in shape, smooth and 

 shining, and of a light orange yellow color when first laid, becoming darker 

 before hatching. A short stalk on the larger end attaches the egg to the 

 bark, and a long thread-like process projects from the smaller end. 



The temperature conditions in the spring influence not only the time of 

 oviposition of the winter brood, but also the duration of the egj^ stage. 

 Eggs brought into the warm insectary on April 7 hatched in eleven days. 

 Other branches containing eggs were tied to trees near by, the end of the 

 cut branch being kept in a vial of damp sand; these eggs hatched in seven- 

 teen days. The weather remaining cool, the eggs upon the trees under 

 natural conditions did not hatch before May 10, or more than a month 

 after oviposition began. By May 18, most of the eggs had hatched; and 

 the hibernating adults had disappeared. 



Habits of the nymph. — Immediately after emerging from the egg, the 

 minute nymph seeks a suitable feeding place and is soon at work sucking 

 the sap with its short beak which appears to arise from between the front 

 legs. The favorite feeding places of the nymph, and to which their much 

 flattened bodies are well adapted, are in the axils of the leaf petioles and 

 stems of the forming fruit. A few nymphs emerged in the spring before 

 the leaves had expanded; these nymphs crawled into the buds out of sight. 

 When the axils of the fruit-stems and leaves become full, the nymphs 

 gather in closely packed clusters about the base of the petioles and stems; 

 if very numerous they gather on the under side of the leaves along the 

 mid-rib and often on the petioles of the leaf. The nymphs move about but 

 very little, sometimes becoming covered with their own honey-dew; if dis- 

 turbed they crawl about quite rapidly. The only times when the nymphs 

 seem to stop feeding is during the casting off of their old skin which has 

 become too small, and which gives place to a new and elastic skin formed 

 just beneath the old one. At the last moulting of the skin, which occurs 

 about one month after the nymph's emergence from the egg, the adult 

 insect appears. 



Habits of the adult. — The adult insect has quite different habits from 

 what it had when a nymph. The strong legs and wings of the adult enable 

 it to spring up and fly away with surprising quickness upon the slightest 

 unnatural jar or the near approach of the hand to its resting place. The 

 hibernating forms, however, are quite sluggish in their movements and are 

 readily captured when found. The summer forms fly readily from tree to 

 tree and could easily be borne by winds for long distances, and thus infest 

 neighboring orchards. The adults are provided with a beak with which 

 they feed upon the tissues of the leaves and tender twigs of the tree. They 

 seem to have no favorite feediug place. 



Oviposition of summer broods. — Three or four days after their trans- 

 formation from the nymph stage, the adults of the spring and summer 

 broods copulate and egg-laying begins for another brood. These eggs are 

 usually laid singly, sometimes several in a row or group, not on the twigs 

 but on the under side of the tenderest leaves among the hairs near the 

 midrib, or on the petiole near the leaf; sometimes the female very adroitly 

 places an egg or two in each notch of the toothed edge of the leaf. The 

 eggs of the summer broods do not differ from those laid by the hibernating 

 adult. The summer eggs, however, hatch in from eight to ten days under 

 the warmer and more even temperature conditions. 



Detailed account of a. single generation. — A detailed study was made of 

 the second generation of the pest to ascertain any peculiarities of any of 



