The Elements of Evolution (43-15-16) Lepidopteran Defense


Many lepidopterans (moths and butterflies) have coloration patterns that act as camouflage. As insectivorous birds have caught on to the ruse, adaptation has furthered the camouflage cycle.

Quite a few lepidopterans have false eyespots that mimic birds of prey that prey upon the small birds that prey upon them. These spots are often displayed with behaviors that startle a predator into thinking that the tables have been turned on it.

Birds are not the only worry for butterflies. Lepidopterans may be laid low by small jumping spiders which can leap on their heads and deliver venom that instantly paralyzes.

The red-banded hairstreak is a butterfly endemic to the southeastern United States. If feeds on fallen tree leaves which are frequently crawling with spiders.

Besides the striping that begat its name, the hairstreak has a pattern on its hind wings that looks like its head. On the ground in the presence of spiders, the hairstreak constantly moves its hind wings to elevate the effect of its false head being real. Spiders are suitably seduced: jumping at the false head, thereby saving the hairstreak from a bad hair day.

The spiders get frustrated with futile attacks. They learn not to bother with prey that they cannot capture. This enhances the efficacy of the hairstreak’s false head.