THE ENTOMOLOGIST. 111 
part, lives in a tube of silk, which it builds and extends often 
several inches beyond the trunk or stem in which it burrows, 
and from which it often, especially when young, issues to 
feed. In this, again, it approaches-the Hesperians, which 
are partial concealers, and live, when not feeding, within 
silken cases or tubes constructed among the leaves of their 
food-plants. 
The pupz of the Castnians, like those of all Heterocerous 
borers known to me, are, according to authors, armed with 
rings of minute spines on the hind borders of the abdominal 
joints—the spines serving a very useful purpose in assisting 
the pupa out ofits cocoon. Heterocerous borers also pupate 
in a more or less perfect cocoon, made either within or 
without the burrow; and, in the issuing of the imago, the 
mesothoracic covering generally collapses, the leg-cases 
become unsoldered, and those of the antenne are always 
separated and often curled back over the head in the exuvium. 
The Hesperians pupate within the silken cavity occupied as 
larva, or else in a separate slight cocoon: the pupa is 
generally attached to a silken tuft by the hooks of the 
cremaster, and sometimes by a silken girth around the middle 
of the body besides: it is not unfrequently covered with a 
slight powdery bloom, and is characterized by the prominence 
of the prothoracic spiracle: the exuvinm more nearly retains 
its form, the leg-cases remaining soldered, and even those of 
the antenne being rarely separated. In not having a well- 
formed cocoon, in being covered with bloom, in the characters 
of the exuvium, in the conspicuity of the prothoracic spiracle, 
but more particularly in the want of minute spines on the 
borders of the abdominal joints, Yucew is again Hesperian 
and not Castnian. Indeed, except in the broader anal flap, 
densely surrounded with stiff bristles, in place of an apical 
bunch of hooks, in the smaller head and larger body, it 
resembles Nisoniades in general form, colour, and texture. 
The typical Castnians, in the perfect state, have the wings 
large with loose and very large scales, and the hind-wings 
invariably armed, at costal base, with the long stout spine, or 
spring, which serves to lock the wings in flight by hooking in 
a sort of socket beneath the primaries, and which is so 
characteristic of the Heterocera, The venation resembles 
more nearly that of the Hepialians, and is totally unlike that 
