In lab trials, spiders caught 6 percent of the metalmark moths presented to them, as opposed to 62 percent of other moth species. What’s more, the spiders sometimes made territorial gestures at the metalmarks — and occasionally backed away.
Question: Now what would cause a spider to back away from a moth?
GrrlScientist provides one very very cool answer (for which she of course gets a peek above our garters!).
For most moths, the sight of a jumping spider makes them panic as they try to escape its lethal pounce. But not so for metalmark moths in the genus Brenthia. These moths stand their ground with hind wings flared and forewings held above the body at a slight angle.
These moths are relying on mimicry to save their lives.
Check. This. Out.
In the comments, Bev Wigney points us toward a post she did on mimicry back in March, with some other very cool mimicry going on, but the top prize for faking it definitely goes to Brenthia.
The original paper (with more and bigger pretty pictures) can be found on PLoS ONE.
Predator Mimicry: Metalmark Moths Mimic Their Jumping Spider Predators
Jadranka Rota*, David L. Wagner
Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, United States of America
From the paper:
All species of Brenthia which we observed possess the same adult behavior: during the day both males and females perch on upper surfaces of vegetation and adopt a peculiar posture (Fig. 2b). Their hindwings are fanned outwards and brought forward, perpendicular to the forewings; the forewings are raised and held above the body at approximately a 45° angle , . In this position, the alternating white and black fascia on the hindwings are reminiscent of salticid legs (Fig. 1). Moreover, both sexes move with short, rapid, jerky motions, in much the same fashion as jumping spiders (see video S2 of live B. hexaselena and B. monolychna). Their exceptional wing posture, in conjunction with spiderlike wing markings and movement, makes Brenthia moths salticid look-alikes.