Literature Review: Hairstreak False Heads

by Carl Strang

Occasionally when trawling through the scientific literature I turn up a study that I wish I had done myself. Such is the case with this week’s feature.

The southern (oak) hairstreak is related to the species in this study. Note the antenna-like extensions on the corners of the hind wings.

The southern (oak) hairstreak is related to the species in this study. Note the antenna-like extensions on the corners of the hind wings.

Andrei Sourakov. Two heads are better than one: false head allows Calycopis cecrops (Lycaenidae) to escape predation by a Jumping Spider, Phidippus pulcherrimus (Salticidae). Journal of Natural History, 2013; 1 DOI: 10.1080/00222933.2012.759288 He conducted experimental studies focused on the shape and color pattern of the lower outer wing corner of a hairstreak. Many of the small butterflies in this group have similar patterns that appear to mimic the head (complete with eyespots and threadlike extensions resembling antennae), at the other end of the insect, and have been speculated as providing some protection from birds. His tests showed that the mimicry was 100% effective against attack by a common jumping spider. The effectiveness appeared to be enhanced by the butterflies’ behavior, moving the wings in a way unlike other butterflies. The spiders always were successful against other butterfly and moth species lacking this pattern.

Another species in the group, the banded hairstreak.

Another species in the group, the banded hairstreak.

Jumping spiders in genus Phidippus have iridescent chelicerae, and the family’s characteristic large eyes.

Jumping spiders in genus Phidippus have iridescent chelicerae, and the family’s characteristic large eyes.

Jumping spiders are visual hunters that leap to capture their prey, so the effectiveness of the butterflies’ deception is a well-matched defense.

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