TACHINID PARASITES OF THE GIPSY MOTH. > gies 
as illustrated in figures 39 and 40. In this stage the larva breathes 
through the spiracle of its host, to which the ‘funnel,’ which is 
apparently formed by the adventitious growth of a main branch of 
the trachea, is directly attached. 
But few of the parasites, the early stages of which have been studied 
at the laboratory, exhibit a more clearly defined physiological rela- 
tionship with their 
host than does Ble- 
pharipa. This re- 
lationship is com- 
parable in many 
ways to that be- 
tween the cynipid 
gall-makers and the 
oak tree which 
serves as their host. 
As is well known, 
many species of cy- 
nipids are closely 
restricted to one 
species of oak, Or, Fic. 38.—Blepharipa scutellata. First-stage larvee: a, Natural size; b, 
at least to: several greatly enlarged; c,c, c, greatly enlarged in situ in atrophied tissue of 
‘ * host. (Original.) 
nearly allied spe- 
cies, and the same is to be expected of parasites like Blepharipa and 
others here spoken of as physiological, and thus limited in their host 
relationships. The gipsy moth itself is comparable to the parasites 
in which the host 
relations are deter- 
mined by physical 
rather than by 
physiological con- 
ditions. Inits 
choice of food, al- 
though it prefers 
oak to almost any 
other of the native 
trees, it can =p 
does attack all « 
nearly all varieties 
of deciduous trees, and even conifers and herbaceous plants when 
necessity demands. 
The development of the Blepharipa is directly correlated to the 
development of the host, and as a parasite of the gipsy moth, its 
larva awaits the pupation of the host before assuming the aggressive, 
and destroying it (Pl. X VIM, fig. 1). Its own pupation is accom- 
plished in the earth (Pl. XVIII, fig. 2), and the pupa develops adult 
Fia. 39.—Blepharipa scutellata: Second-stage larva in situ ina portion of 
its tracheal ‘“‘funnel.’’ Greatly enlarged. (Original.) 
