72 Journal of Agricultural Research voi. x. no. a 



rarely mottled with orange; the abdomen bears a certain amount of 

 bluish white pubescence, and on the caudal segment is a tuft of short 

 white "wool"; the cornicles are black, very short; the antennae are a little 

 over one-third the length of the body, dark greenish or yellowish brown, 

 joints III to VI bearing transverse sensoria ; the legs are light orange, the 

 apical third to half of the femora is dark brown, the base and apex of the 

 tibae and the tarsi are light gray ; the beak is pale yellow at base, elsewhere 

 dark grayish brown, reaching the second coxae; the stigma is a grayish 

 green. 



In 1 91 6 the earliest spring migrants transformed in advanced galls 

 exposed to maximum sunlight as early as June 8. On a young, par- 

 tially shaded cork elm in the laboratory premises at Walnut Creek, Cal., 

 the first migrants transformed on June 16, after a growing period of 

 about 24 days. By the fourth week in June nearly every gall examined 

 contained winged forms, and by July 10 large numbers of the earlier 

 galls had been forsaken, all the inmates destined to acquire wings having 

 transformed and flown off. By the end of July hardly a gall with living 

 inmates could be found. Between June 19 and July 24, records were 

 kept of the migrant production in three galls confined with cheeseclotU, 

 on a small cork elm. Respectively, 114, 107, and 76 winged individuals 

 issued from them; in the first case the last migrant developed on July 15, 

 in the second on July 21, and in the third on July 24. These galls were 

 imder the average size, and, moreover, at least as many larvae as per- 

 sisted forsook the galls, probably as a result of the handling to which 

 they were subjected. On July 17 a gall infestation, mostly on large 

 leaves, was examined, and over a thousand pupae and larvae were esti- 

 mated to be inhabiting the larger galls of from 2>^ to 3K inches maximum 

 diameter. To judge by the total counts made, it is probably not an 

 exaggeration to say that the gall of average size produced in 191 6 at 

 least 400 winged forms (migrants), and, as a heavily infested elm tree 

 may contain as many as 400 galls, the enormous number of spring mi- 

 grants produced can be imagined. Great numbers, however, were caught 

 in spider webs on the elms; many others, including pupae, became 

 "choked" through the honeydew deposits within the galls, while the 

 larvae and pupae suffered considerable loss in numbers through predatory 

 insects which were able to gain admittance to the interior of the galls 

 after the middle of June. Among these predators adults of Scymnus spp. 

 (Coccinellidae) and chrysopid larv^ae were most notable and abundant. 



Spring migrants were observed resting on pear foliage and actively 

 crawling up and down the lower part of pear trunks. Young deposited 

 by them were taken in spider webs at the base of pear trees, and it 

 appears that the young are normally deposited on pear trunks at or near 

 to the soil surface. Spring migrants when placed in petri dishes with 

 pieces of pear roots on wet sand deposited young which readily settled 

 and fed upon the roots and which precisely resembled in structure — albeit 



