442 journal of economic entomology [vol. 12 



Life History 



There are two generations of the insects a year at Ithaca. The 

 first brood hatches in July from eggs laid in late May and June, and 

 the nymphs become mature in from 20 to 25 days after hatching. The 

 second brood eggs are laid in late July and August and the adults ap- 

 pear in late August and September. 



Hibernation. — The adults of the second brood hibernate among 

 the fallen leaves and in crevices of the bark. Many of them remain 

 on the leaves upon which they were feeding before the leaves fell. 

 They appeared the last of May and during early June at Ithaca in 

 1918 were feeding on the new Cratsegus leaves. As a rule only one 

 pair of adults was found on a leaf and they remained feeding and 

 o^dpositing on that same leaf for several days. After emergence from 

 the nymphal skin in September, the adults of the second brood con- 

 tinue feeding on the leaves until the latter fall, in late September or 

 October. The insects were feeding last fall after two heavy frosts. 



Egg. — The egg is subelliptical in shape, with the basal end rounded, 

 and the apical end bent slightly to one side and capped with a rather 

 broad cylindrical collar surmounted by a low cone with irregular 

 ridges extending from base to apex. From the apex of this cone there 

 sometimes arises a short blunt prolongation but often this is absent. 

 The egg is without waxy covering over the chorion which is smooth, 

 and unsculptured, and of a shining dark-brown color but somewhat 

 lighter toward the base. The cap or cone is often whitish. The egg 

 exclusive of the apical prolongation of the cap is 0.52 mm. long and 

 0.21 mm. broad at its greatest width. 



The eggs are laid on the under surface of the leaf in the axils formed 

 by the midrib and its lateral branches. Although the female has a well 

 developed, saw -like, four-valved ovipositor, the eggs are not inserted 

 into the leaf tissue. They are placed among the hairs on the veins and 

 are sometimes glued together with an adhesive material. Thej^ are 

 generally laid in small groups, some groups containing as many as 18 

 or 20 eggs and occasionally the eggs are laid singly. In counting the 

 number of eggs on 100 infested leaves I found an average of 49 eggs per 

 leaf. Occasionally a leaf had 75 or 80 eggs on it. The egg-lajdng 

 period extends over several weeks so that eggs, nymphs and adults 

 may be found at the same time in July and August. 



Eggs laid June 2 hatched on July 9 and 10 while the eggs of the 

 second brood, laid July 29 and 30, hatched August 15 and 16. This 

 indicates an incubation period of about 37 days in the cooler tempera- 

 ture of June and 18 days in July and August when the average tempera- 

 ture was higher. 



The conical egg cap is pushed up by the nymph as it begins to emerge 



