Length: 20-40 mm in the genus
These interesting beetles have two roundish light organs on the dorsum of the pronotum, and a third on the first abdominal sternite. Unlike fireflies, headlight beetles do not produce a flash pattern, but instead emit a continous light.
Charles L. Hogue notes, "In flight, both sexes produce a brilliant blue-green streak of light that dazzles the onlooker."
A number of traveller's tales describe this beetle's bright light and its light being utilzed by native peoples. Doubtless many of these stories are exaggerated. As early as 1516, Peter Martyr in his History of the West Indies wrote, "the islanders … go with their good will by night with two Cucuji tyed to the great toes of their feet: for the traveler goeth better by the direction of the light of the Cucuji, than if he brought so many candles with him" (quoted in Hogue, 1993).
Martyr's 1516 work suggested these beetles are useful not only as living torches but also as predators of mosquitos, but in fact headlight beetles as adults live on plant materials such as fermenting fruit. The larvae, on the other hand, live in the soil and feed on the larvae of other beetles.
The larvae and the pupae too have light organs and emit a greenish glow.
With their interesting biolumiscent properties, we could hard expect the headlight beetles to sport bright colors or jaunty markings, and in fact all members of the genus are dark brown and fairly plain. The antennae are serrate. As is typical in elaters, the rear pronotal angles each feature a backward-pointing "tooth."
Photo location: Arima Valley, Trinidad.