Come October, costumes start appearing throughout the Forest Preserves of Cook County. Superheroes, ghosts, witches and other little monsters attend all the spooky events the Forest Preserves have to offer. But if you look beyond the trails and nature centers, the costume party has actually been underway all year.
Some insects and spiders are masters of disguise, changing their appearance, impersonating more intimidating creatures or covering themselves completely. These costumes are not for collecting candy. They can mean the difference between catching dinner and becoming it.
Goldenrod crab spider: The camouflage costume
Spotting a goldenrod crab spider can feel like finding something that was never meant to be found. These ambush hunters camouflage themselves among flowers, changing colors in between molts to match, where they wait for unsuspecting prey such as flies, bees and damselflies to venture close enough to grab.
For a predator that does not need to chase down dinner, blending into the background is an effective costume.
Marsh fly: The wasp costume
Marsh flies may cause a visitor to hesitate before getting too close. Its markings resemble those of a yellow jacket wasp.
That resemblance is part of a trick seen among many hover flies that imitate wasps. Looking like something capable of delivering a painful sting can be useful when potential predators are deciding what belongs on the menu.
Hummingbird clearwing moth: The bird costume
A hummingbird zips toward a flower, hovers in midair and reaches in for a sip of nectar. At least, that is what it might look like at first.
The hummingbird clearwing moth puts on a convincing impression. Unlike many moths, this species is active during the day, when it can be spotted hovering in front of flowers and unfurling its long proboscis[SD1] , or elongated appendage attached to its head, to feed. Its wings have large transparent areas and beat rapidly as this strong flier moves from bloom to bloom.
Case-bearing leaf beetle: The hand-me-down
For certain case-bearing leaf beetles, mom picks out the first costume.
A female begins creating a protective case when she lays her egg. After hatching, the larva adds to it and carries the case on its back as it grows. The materials involved can make this particular Halloween comparison a little gross: fecal matter is part of the construction.
Black swallowtail caterpillar: The snake costume
A black swallowtail caterpillar has a costume it keeps hidden until trouble arrives.
When disturbed, the caterpillar can extend a pair of appendages that resemble a snake’s forked tongue. The sudden appearance is designed to startle a would-be predator, buying the caterpillar precious time when something gets too close.