Crackers

[Jeff Crolla/Martha Hancock]

LOL! well Mary Beth maybe others from the SW or central america can provide more info, but in the interests of keeping you from "cracking" yourself, hope this helps!

from The Butterflies of North America by James A. Scott, Stanford University Press, Stanford, California, 1986 (there is info on 8 species of Cracker - may be in a local library)
under Gray Cracker (Hamadryas februa): "Hamadryas adults land upside down with the barklike wings flattened against tree trunks for camouflage. To await females, males perch on trees and dart out at passing butterflies, insects, even people, often making a "cracking" sound with the abdomen. Males of all Hamadryas species - except perhaps H. atlantis and H. iphthime, which are poorly studied - share this behaviour, which males evidently use to discriminate males from females (males may pursue only non-cracking adults), and which accounts for their common name. Hamdryas males have two long lateral spiny rods extending backward from abdomen segment 8, which probably produce the cracking sound when the valvae twang the rods (using a spiny dorsal part of the valva; the spiny parts and rods are longer in species that often crack). The sounds are produced only in flight, for unknown reasons. Both sexes have tympana on the under forewing base, which S. Swihart proved detect sound but cannot produce it."

pictures of larva & pupa of Gray Cracker and info:

http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/TX/16.htm

picture of adult Gray Cracker here:

http://www.mesc.usgs.gov/butterfly/latin_america/latin_america.html

article from American Butterflies with some info on etymology of the Cracker names:

http://www.naba.org/pubs/ab97d/p36.html

pictures of 5 species of Cracker here under Subfamily Limenitidinae:

http://nitro.biosci.arizona.edu/zeeb/butterflies/oldsorlist.html

all best
Jeff

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