PREDATORY CAPTURE OF BOMBARDIER BEETLES 
BY A TABANID FLY LARVA* 
By Stephen Nowicki and Thomas Eisner 
Section of Neurobiology and Behavior 
Cornell University, Ithaca, NY 14853 
While collecting bombardier beetles {Brachinus spp.) on the eve- 
ning of August 27, 1982, by a pond near Portal, Cochise County, 
Arizona, a group of us, including Rodger Jackman of the British 
Broadcasting Corporation and Maria Eisner, came upon an unusual 
phenomenon. Thousands of young adults of the spadefoot toad, 
Scaphiopus multiplicatus, were active beside the pond on that 
night, having just emerged from the water after metamorphosis. On 
close observation we noted a number of these toads that were dead 
or dying and in various stages of partial submergence in the mud. 
Each had been grasped from beneath by a larva of the horsefly 
Tabanus punctifer, a mud-dwelling predator, which had seized it with 
its hooked mouthparts, had pulled it partly into the substrate, and 
was embibing its body fluids. Details of this first known occurrence 
of predation by a fly larva on an adult amphibian will be published 
elsewhere. Our purpose here is to call attention to another extraor- 
dinary ability of this larva: the capture of bombardier beetles. 
We transported several of the larvae to our Cornell laboratories 
and established them individually in mud-filled enclosures, where 
they quickly buried themselves, leaving only their mouthparts 
exposed at the surface (Fig. lA). We maintained the larvae on 
young spadefoot toads, which they captured as they had in the field, 
and also on insects, which judging from published accounts on 
tabanid larvae (Webb and Wells, 1924; Oldroyd, 1964; Burger, 
1977), must be a principal staple of their diet. They proved capable 
even of capturing large crickets ( Teleogryllus oceanicus), which they 
hooked by a leg, drew partly into the mud, and then held for hours 
while sucking out their body contents. 
*Paper No. 73 of the series Defense Mechanisms of Arthropods. Paper No. 72 is 
T. Eisner and J. Meinwald, Psyche 89, 357-367, 1983. 
Manuscript received by the editor January 6, 1983 
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