92 
Journal New York Entomological Society. 
[Vol. IV. 
NOTE ON THE HEAD SET.® OF LEPIDOPTEROUS 
LARV®, WITH SPECIAL REFERENCE TO 
THE APPENDAGES OF PERO- 
PHORA MELSHEIMERII. 
By Harrison G. Dyar, Ph. D. 
The peculiar flattened antenna-like organs on the head of Cicinnus 
melsheimerii have long been known. Harris says : “ On each side, just 
behind the five ocelli, are two flexible, slender, spathulate antennae (?) 
which, however, seem to be without joints and incapable of motion.” 
Again he says: “On each side of the middle of the head there is a 
black flexible kind of antenna, very slender where it joins the head and 
broader toward the end like the handle of a spoon.” Dr. Packard re¬ 
marks : 1 1 This larva is especially remarkable for new structures not known 
to exist in any other caterpillars, viz., a pair of long appendages, the 
use of which is quite unknown. They arise by a slender stalk behind 
and a litde above the eyes, on each side of the head; the base is cylin¬ 
drical, but the appendage soon becomes flattened or compressed and 
flattened bulbous at the end. The structures are brittle, not flexible, 
and they easily break off.” From the foregoing it would appear that 
the homology of these structures has not been recognized, although it 
is a very simple one. The structure is an enlarged and flattened seta, 
exactly analogous to those on the body of Apatela funeralis and a few 
other larvae. That one of the head setae should assume this form is per - 
haps unique, but no more surprising than that some of the body setae 
should do so. As to its function we are ignorant, as is also the case in 
regard to the Apatela , though we may surmise that in both cases it is to 
present a terrifying appearance toward small enemies. In A. funeralis 
these grotesque setae certainly heighten the effect produced by the con¬ 
spicuous larval coloration, and it may be that in C. melsheimerii , when 
the head is protruded from the case, these setae on it have a similar 
deterrent effect. 
Figure i represents the front view of the head of a larva belonging 
to the Noctuina (Agrotides). I have numbered the setae on the epi- 
cranium from above downward. Setae i and ii are near the median 
suture, iii in the central part of the lobe, iv above and before the fourth 
ocellus (numbered from below upward), v behind the fifth ocellus, vi 
behind the eyes as a whole on a level with the third ocellus, vii is 
