Friday, February 16, 2018

Cracker Butterflies

Crackers are butterflies found from Arizona and southern Texas south across most of Central and South America. Nine species are found in Costa Rica. We found two species at the Hotel de Campo on 11 July. Both perched on tree trunks. Crackers always perch with their heads pointed downward. They feed on fruit and tree sap.

The first is a Starry Cracker, the second is a Gray Cracker. Males make a loud crackling sounds when the fly from their perches. The sound comes by their “twanging a pair of spiny rods at the tip of the abdomen against bristles on the anal claspers” (Dennis Paulson, pers. com,). They make these noises as part of their territorial displays and also when predators approach. Just how these butterflies hear their noises is not well understood, and they may have more than one kind of hearing organ located in their wings. They can hear each other and also hear bats’ sonic calls.

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