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.

More Mayslake Lepidoptera (and others)

by Carl Strang

A couple days ago I updated the dragonflies and damselflies I have been finding at Mayslake Forest Preserve in my first year there. Today I’ll continue with newly sighted butterflies and a moth. These include black swallowtails, both female

black swallowtail female b

and male.

Black swallowtail male b

I have not seen larvae, but there are plenty of Queen Anne’s lace and other members of the family Umbelliferae that are potential food plants. When I saw the following hairstreak, I made sure to get photos.

Banded hairstreak b

This proves to be a banded hairstreak. A year ago I was alerted by Forest Preserve District invertebrate biologist Tom Velat to watch for southern or oak hairstreaks. That alert was prompted by the following photo I took of that species at Fullersburg, which I failed to identify correctly.

Southern (oak) hairstreak b

The hairstreaks require a close study of patterns in the lines of dots beneath both wings, and the arrangement of colors in the corner of the hindwing. I have one moth to share this time, the reversed haploa.

Haploa reversa Reversed haploa b

Haploa is a genus of tiger moths. I’ll close with three insects of milkweeds. The first is a familiar butterfly, the monarch, here visiting a purple coneflower in Mayslake’s Historic Garden.

Monarch Echinacea b

Monarch caterpillars feed on the leaves of milkweeds, in the process sequestering defensive poisons which then protect the specialist insect from its own consumers. Other insects have solved the milkweeds’ chemical challenge, and gone on to advertise their own poisonous status with bright colors. Two species in this category which recently have appeared at Mayslake are the red milkweed beetle

Red milkweed beetle b

and the large milkweed bug.

Large milkweed bug b

I’m sure I have barely scratched the surface of Mayslake’s Lepidoptera.

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