STARTLE BEHAVIOR IN AN ASCALAPHID 
(NEUROPTERA) 
By Thomas Eisner 1 and Phillip A. Adams 2 
According to van der Weele (1908), male Ascalaphidae of the 
genera By as and Haploglenius have a peculiar hinged flap covering 
the pronotum. The flap is more or less developed in different spe- 
cies, and in some conceals a bright pronotal patch. No mobility or 
function was ascribed to the flap. On November 17, 1968, while 
blacklighting at the Smithsonian Tropical Research Station, Barro 
Colorado Island, Canal Zone, one of us (T.E.) had occasion to 
observe the response to manipulation of a male of Haploglenius 
luteus that had come to rest at the light. Every time the insect was 
poked or seized, it abruptly exposed its patch, which in this species 
is brilliantly white-pruinose and contrasts sharply with the drab 
remainder of the body (Figs. 1-3). We suggest that this “flashing” 
behavior is defensive in function. Whether it merely startles preda- 
tors or serves also as reinforcement of distastefulness cannot be said, 
since nothing is known about the palatability of Haploglenius (some 
ascalaphids have a bad stench and may be distasteful). The startling 
function need not be the only, or for that matter primary, function 
of the flap. Since the device is restricted to one sex, it probably 
serves also for signalling purposes in courtship. 
Literature Cited 
van der Weele, H. W. 
19C8. Ascalaphiden: Monographisch Bearbeitet. Coll. Zool. Selys 
Longchamps Fasc. VIII: 1-326 (2 Plates). 
Section of Neurobiology and Behavior, Division of Biological Sciences, 
Cornell University, Ithaca, New York 14853. 
department of Biology, California State University, Fullerton, California 
92634. 
Manuscript received by the editor February 10, 1976. 
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