
No. 427.] HAIRS OF LEPIDOPTEROUS LARVA. 575 
Differing from the hairs just described, there are distributed 
over the surface of the body of the larva of the Io moth spine- 
like clusters, prolongations of the body 
wall (Fig. 22); most of these spines are 
tipped with short, strong, chitinized caps, 
and a few with long, slender, hairlike 
processes. These spines when touched 
to the tender surface of the hands pro- 
duce swellings which are slightly painful. 
Numerous specimens stained by methylen : 
blue demonstrated fine nerves running ri; simple hair from Chisio- 
into these spinous processes and extend- fmit mp: 
ing almost to the tips, but no bipolar nerve cells were demon- 
strated. Evidently here we have glandular hairs, but not 
sensory hairs; however, in the same 
specimens there were found hairs of the 
usual type, much smaller than these proc- 
esses of the body wall or spines; these 
true hairs were located both on the bases 
of the spines and upon the body wall 
between the spine clusters (Fig. 22, A). 
No difficulty was experienced in demon- 
strating a bipolar nerve cell at the base, 



y 
Fic. 18. — Silver-spotted ue of each of these true hairs. 
To summarize briefly : all lepidopter- 
ous larvas studied have their bodies clothed with hairs, and all 
the hairs are sensory, having a bipolar nerve cell at their base 
and supplied with a minute nerve fiber, \ 
with the possible exception of the 
poison spines of Io caterpillars. 
To carry the generalizations a little 
further, the following observations are 
useful. In the larvae of May beetles 




; : g 
the hairs of the body surface are sup- Fic. 19. — Large, probably glandular 
plied with bipolar nerve cells (Fig. 23), 
and in Orthoptera, as already spoken of by Duboscq (97), the 
hairs have a bipolar sense cell at their base. In the larva of 
Corydalis, bipolar nerve cells with their fibers supply each of 
