14 
of May or early in June; the remainder leaving the galls gradually 
till the end of June or early in July, by which time the last ones have 
disappeared. Frequently, however, a few stragglers may be met with 
as late as the end of July issuing from belated galls, the product of 
a few stem-mothers, hatching from eggs deposited very late in fall 
during an exceptionally favorable season. 
There is but a single migratory generation in each gall, all of which, 
after casting four skins, become winged and leave the gall after hav- 
ing fully matured and migrate to birches, where they deposit their 
larve on the underside of the leaves, which, in favorable years, 
become frequently covered with migrants. So keen and unerring 
must be the instinet of these migrants to discover their secondary 
Fia. 5.—Hormaphis hamamelidis; Second generation; a, young larva; b, pupa; c,spring migrant; 
d, antenna.—Much enlarged (original). 
host that they frequently fly great distances in search for birches, 
which may not be growing in the immediate neighborhood of witch- 
hazels, as is the case in some localities along the shore of the Potomae 
River, which they are compelled to cross in order to reach young 
birches on the opposite shore. 
Second generation, first stage (Fig. 5).—The young larve of this 
generation are at first pale purplish and slightly covered with a white 
powder; they soon change to a dark purplish-brown, the eyes are 
black, and the antennee and legs pale dusky. They measure about 
0.3" in length, and are of a regularly oval shape; the front of the 
head is almost straight, and the surface of the body appears to be 
densely granulated. There are two rather long bristles on the front 
