In past episodes, Bug of the Week visited several ferocious predators like the six spotted green tiger beetle, fiery searcher, and multicolored Asian lady beetle that make their living actively hunting, capturing, and consuming hapless prey. Ah, but speed and power are not the only wiles employed by predators. Sometimes stealth and deception work just as effectively as strength and speed when it comes to earning dinner. The warm days of September are a time when many members of the aster family put on their finest show. Bright yellow blossoms of goldenrod are like magnets to dozens of pollinators including bees, wasps, flies, and beetles (see“The goldenrod gang”, and “Beautiful in yellow and black”).
Little do they know that lurking among yellow flowers are deadly masters of disguise such as ambush bugs and the crab spiders. The irregular body outline and beautiful patchwork of yellow and brown enables the ambush bug to blend with the yellow and brown patterns of the goldenrod flower. These sly killers sit and wait motionless for hours until an unsuspecting victim lands nearby to collect pollen or sip nectar. With a flick of its greatly enlarged raptorial front legs, the ambush bug snares prey as large as or larger than itself. It is so adept at capturing honeybees that some beekeepers consider it a pest.
With legs outstretched a stealthy crab spider waits for the kill.
With the victim in its grasp, the ambush bug inserts its beak into its prey and injects paralytic saliva. Digestive enzymes break down the tissues of the immobilized victim and its liquefied remains are sucked through the beak into the gullet of the ambush bug. Yum! Tucked among the blossoms is another secretive killer, the crab spider. It too sports a camouflaged costume of pale yellow with bands and patches of brown. Two pairs of extra long front legs resembling claws of a crab and give crab spiders their common name. With legs outstretched legs, the spider awaits a bee or fly to blunder within reach. Outstretched legs snap shut with surprising speed and embrace the victim while a bite from venom-laden fangs bring a quick end to the prey. Like the ambush bug, the crab spider secretes digestive enzymes to liquefy the tissues of its feast. Some crab spiders may change color to better match flowers in which they hide. Sometime over the next several weeks take a few moments to wander into a meadow or along its edge to investigate goldenrod and the stealthy predators that lurk within.
References:
We thank Melissa for sending her image of an ambush bug that served as an inspiration for this story. An Introduction to the Study of Insects by Borer, De Long, and Triplehorn and the National Audubon Field Guide to North American Insect and Spiders by Milne and Milne were used as references for this Bug of the Week. To learn more about ambush bugs and crab spiders, please visit the following web sites.
http://www.uky.edu/Ag/CritterFiles/casefile/insects/bugs/assassin/assassin.htm
http://www.uky.edu/Ag/CritterFiles/casefile/spiders/crab/crab.htm