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Psyche 
[Vol. 90 
Figure 1. (A) Mouthparts (arrow) of a buried T. punciifer larva, projecting just 
above the surface of the mud, as the animal lies in wait of prey. (B) Bombardier 
beetle, caught by a submerged larva and partly drawn into the mud, in the process of 
being eaten (the larvae can also pull beetles into drier mud than here shown). (C) Full 
grown T. punctifer larva beside an average-sized bombardier beetle. Reference bars = 
5 mm. 
Bombardier beetles are doubtless among the most invulnerable of 
insects. The quinone-containing spray that they eject from their 
abdominal defensive glands when attacked is hot (100°C) and is 
aimed accurately toward the predator by rotation of the abdominal 
tip (Eisner, 1958; Aneshansley et al., 1969). A number of broadly 
insectivorous predators have been shown to be repelled by the 
spray, including ants, spiders, preying mantids, and toads (Eisner, 
1958; Eisner and Dean, 1976; Dean, 1980). 
We staged encounters between bombardier beetles and T. punc- 
tifer larvae by releasing the beetles singly onto the mud in the larval 
