SECOND SERIES: PEMPHIGUS TESSELLATA FITCH. 15 



and head, whereas the ventral side of the body was densely covered 

 with a short and white secretion. 



September H^ 1897. — A lot of migrants from alders were placed in 

 a tube to obtain their progeny. By the following day they had de- 

 posited a number of larva? which, on examination, proved to be the 

 sexes, or males and females, of this species, both of them without 

 a rostrum. The females were about twice as large as the males and 

 of a bright yellow, whereas the males were greenish or greenish 

 yellow. The antennae and legs of both were colorless. Each of the 

 females contained only one egg. 



Most of the males were dead about 7 days later, whereas most of the 

 females were still alive, active, and mature. These females had 

 cast four skins, which in most cases were still attached, in a con- 

 tinuous string, to the end of the body. None of the females had in- 

 creased in size, and they looked the same as before. Some had 

 secreted a quantity of rather long and woolly secretion, which covered 

 the posterior half of the body. 



September %1^ 1897. — On examining the trunks of maples near 

 Eosslyn, Va., I discovered one of the sexual females in a crack of the 

 bark, in the company of a migrant from alder. 



SepteTYiber 30, 1897. — Examined the trunk of a European alder on 

 the Agricultural grounds, the branches of which were still covered 

 with this insect; on the trunk were also a few migrants, though I 

 failed to find any of the sexes or the winter eggs ; there were, however, 

 on the rough bark and tucked away in cracks or cavities large num- 

 bers of hibernating larvae, while others were still coming down. 



November <§, 1897. — Reexamined the same tree, and found again 

 numerous hibernating larvae in cracks and in empty egg-cases of 

 spiders, but none of the sexes or winter eggs ; these larvae were either 

 covered with a bluish-white secretion or ornamented with 6 dorsal 

 rows of squarish, mealy patches, giving them a pretty, checkered 

 appearance. 



After an unavoidable intermission of a number of years, observa- 

 tions on this particular aphis were again taken up in 1903. 



Jcmiiary 11., 1903. — While again examining alders on the Agricul- 

 tural grounds, large numbers of colonies of this species were seen 

 on the shoots, all of them being covered with cottony secretion. On 

 examining these colonies it was found that all of the apterous females 

 wore dead, having evidently been killed by the late frosts, but under- 

 neath them, and between, were found live and active hibernating 

 larvae, which evidently had been protected against the wintry blasts 

 by the covering of their dead mothers. 



September ^7, 1905. — A few colonies on alder were found near the 

 Chain Bridge, District of Columbia, and among them numbers of 

 return migrants. 



