One of the many reasons only numb-skulls douse their whole gardens with insecticides nowadays is that we've come to realize that many insects help plants by eating bugs that devour plants. Among the coolest of beneficial insects are the aptly-named assassin bugs. These ninjas of the insect world fearlessly stalk, attack, and consume many harmful and annoying pests without you ever knowing they were there.

Take a gander at the drama unfolding below. A milkweed assassin bug, distingusihed by its red-and-black body, has set its sights on a pesky fly. Any guesses how this scene turns out?


Many genera and species of assassin bugs exist in the world. And though some tropical species seek out people, those in the U.S. are entirely beneficial. They range from about 1/2-inch to 1-1/2 inches long, and depending on the species and stage of life, may be green, red, orange, yellow, black, brown, or gray. Narrow heads with very long antennae are trademarks. Assassin bugs are active hunters and target caterpillars, aphids, leafhoppers, beetles, spiders -- really, anything they can catch, even prey much larger than themselves. Once they spot a victim, they uncoil their weapon -- and what a weapon it is.


It's a long, jointed proboscis or beak that works like a hypodermic needle. The assassin bug keeps it curved beneath its head when not in use. But when the dinner bell rings, it straightens out the beak and plunges it into its next meal. Toxin paralyzes the victim, while digestive juices turn its insides into goo that the assassin bug sucks out. Mmmm-mmmm, good.


Unlike most insects, assassin bugs produce only one generation a year. So if you wipe them out through indiscriminate spraying, you're nuking your garden's own troops. Assassin bugs are harmless to people unless you're dumb enough to handle one. In that case, you may find yourself on the receiving end of a painful bite. The worst offender in this regard is the largest assassin bug (show below), called the wheel bug. Named for its wheel- or sawblade-shaped crest, it won't hesitate to bite you too. (Remember the gross scene from "Starship Troopers" where the smart bug shoves its beak into the head of a trooper and sucks out his brain? It's kinda like that.)


This morning, I spotted a little juvenile assassin bug (like the green one eating dinner pictured above) on my red coleus, so I took his picture (below) to show you the relative size.


I sometimes spot assassin bugs in the house too, inevitably having hitched a ride on a plant brought in. Each time, I carefully coax them to crawl onto a piece of paper and take them outside to my garden. My plants could use some more assassins. How about yours?

Thanks to Steve, motleypixel, clicksy, and accent on eclectic for the cool pix.