"92 Journal New York Entomological Society. [Voi. iv. 



NOTE ON THE HEAD SET^ OF LEPIDOPTEROUS 



LARVAE, 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 

 mehheimerii have long been known. Harris says : " On each side, just 

 behind the five ocelli, are two flexible, slender, spathulate antennje ( ? ) 

 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 : ' ' 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 {q\n 

 other larvae. That one of the head setse should assume this form is per- 

 haps unique, but no more surprising than that some of the body setse 

 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 sette certainly heighten the effect produced by the con- 

 spicuous larval coloration, and it may be that in C. melsheiinerii, when 

 the head is protruded from the case, these seta^ on it have a similar 

 deterrent eff"ect. 



Figure i represents the front view of the head of a larva belonging 

 to the Noctuina (Agrotides). I have numbered the set^e on the epi- 

 cranium from abo\e 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 



