CAPTURE OF BOMBARDIER BEETLES 
BY ANT LION LARVAE' 
By Jeffrey Conner and Thomas Eisner 
Section of Neurobiology and Behavior 
Cornell University, Ithaca, NY 14853 
Ant lions (larvae of Myrmeleontidae) are well-known for their 
unique method of prey capture (Wheeler, 1930). They construct a 
conical pit in the sand and lie buried at the bottom with only their 
sickle-shaped mandibles, or head and mandibles, exposed. When an 
ambulatory arthropod falls into the pit it is seized and pierced by the 
mandibles and sucked dry. Bombardier beetles, like other Carabi- 
dae, are ground foragers and thus may be expected to fall into ant 
lion pits. However, due to their singularly effective chemical defense, 
some question remained whether they might be vulnerable to cap- 
ture by ant lions. Bombardier beetles respond to attack by ejecting 
an aimed spray of hot (100° C) repellent quinones from the tip of the 
abdomen (Eisner, 1958; Aneshansley et ai, 1969). The spray is an 
effective deterrent to a number of insectivores (Eisner, 1958; Eisner 
and Dean, 1976). Several authors (Turner, 1915; Wheeler, 1930; 
Lucas and Brockmann, 1981) have observed that ant lions may pull 
their prey under the sand after grasping it. Lucas and Brockman 
(1981) suggest that this behavior may protect ant lions from aggres- 
sive prey. We here report that ant lions can capture bombardier 
beetles providing the ant lions have pulled their head beneath the 
sand by the time the beetles eject their spray. 
Our observations were made at the Archbold Biological Station, 
Lake Placid, Highlands County, Florida, where the ant lions {Myr- 
meleon crudelis larvae) and bombardier beetles {Brachinus spp.) 
were taken. Fifteen ant lions were placed in each of three metal 
boxes (30 X 44 X 18 cm high) filled with sand to a depth of 8 cm. 
After the ant lions had constructed pits, bombardier beetles were 
released individually into the boxes and observed until they slid or 
walked into a pit and were seized by an ant lion. Two things were 
noted each time a beetle “fired” after being grasped: (1) whether the 
'Paper No. 75 of the series Defense Mechanisms of Arthropods. Paper No. 74 is T. 
Eisner and S. Camazine, Proc. Nat. Acad. Sci., in press. 
Manuscript received by the editor February 25, 1983. 
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