The One Kind of Bug You Want in Your Garden

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What Are Assassin Bugs? All You Need to Know About These Beneficial Bugs


If you’re like most gardeners, you spend an inordinate amount of time (and chemicals) trying to banish bugs that could destroy your harvest and strip your colorful blooms. While you can probably spot such culprits as aphids, squash bugs, and tomato worms, you might not know that other insects can be your secret weapon against them. Like characters in an espionage novel, there’s a whole class of assassin bugs lying in wait to wallop the crawlies you most despise. Learn to understand them here!

RELATED: The Good Guys: 8 Beneficial Bugs for Your Garden


Assassin bugs are members of the Reduviidae family, and true to their name, these tiny ninja warriors prey on the enemies of precious plants. So its no wonder that experienced gardeners view them as friends—especially those who take a natural approach and like to limit their use of pesticides. Assassin bugs blithely poison and then devour their victims, but there are caveats. For one thing, these killers don’t discriminate, so they’re just as apt to go after the lady beetles (also known as ladybugs) that also feed on small insects like aphids. They also can administer a painful bite to people and pets, so it’s wise to take care around them.

Assassin Bugs 101: All You Need to Know About Wheel Bugs


With more than 160 species of assassin bugs in North America (nearly 3,000 worldwide), you might wonder how it’s possible to identify the little buggers. Fortunately, they share some recognizable characteristics. As adults, they range from ½- to 1-¼-inch in length, and many are brown, gray, or black, although a few are brightly colored. They have round protruding eyes, six legs, long antennae, and a long narrow head that gives them the appearance of having a neck. Their most easily identifiable feature is a sharp, three-segmented hollow beak, called a “rostrum.”

Here’s the 411 on two common species.

Pest enemy number one: The most highly recognizable assassin is the wheel bug. At 1-¼-inch in length, it’s the largest species in North America, gray in color and sporting a raised semi-circular crest on its back that resembles a wheel with protruding spokes. It’s the easiest assassin bug to ID, and also the most common.

Assassins that ambush: Ambush bugs, a subfamily of assassin bugs (Phymatinae), are so named because they blend in with their surroundings and remain very still, catching their unsuspecting prey off-guard. They’re among the smaller assassin bugs, reaching only ½-inch as adults, but like their fellows have the same three-segmented rostrum and elongated head. The most common type of ambush bugs in North America are jagged ambush bugs, identifiable by their flat triangular bodies with serrated edges. Jagged ambush bugs come in a variety of colors, including green, which allows them to camouflage themselves easily on plant leaves.


With their needle-sharp rostrums, assassin bugs pierce the bodies of their victims and inject a lethal toxin that quickly kills the unlucky insect or caterpillar. The toxin also liquefies the insides of prey, and the assassin then sucks up the liquid through its hollow rostrum; when done feeding, it leaves behind just an empty shell. Assassin bugs can also use their long rostrums in self-defense when necessary, being able to squirt venom up to an inch in some cases.


What Are Assassin Bugs? All You Need to Know About These Beneficial Bugs



If you have a garden, even a small one, or a few outdoor container plants, odds are you have a few assassin bugs. Most have no preference for a specific type of plant, and they hang out in orchards, vegetable gardens, ornamental flowerbeds—virtually everywhere their prey is also found. Ambush bugs, however, are attracted to blooming plants and flowering trees; flowers with large blooms, such as sunflowers, are among their favorite hunting grounds.

In fall, the female assassin bug deposits her eggs under leaves and in plant crevices. The eggs overwinter and then hatch into nymphs (immature bugs) the following spring. The nymphs undergo several growing stages, each one accompanied by the shedding of its skin (molting), and by summer, the nymph reaches adulthood. Assassin bugs are resilient—nymphs, adults, and eggs can all survive temperatures below zero, so assassin bugs are capable of living several years.


What Are Assassin Bugs? All You Need to Know About These Beneficial Bugs



Assassin bugs can be a natural gardener’s best friend, controlling detrimental insects without chemical pesticides. If you have more plant-eating insects than assassin bugs, however, you may need to give them a leg-up by applying a narrow-spectrum pesticide designed to kill only a specific type of insect. A narrow-spectrum pesticide that kills only ants, for example, won’t harm assassin bugs. Since some assassin bugs are attracted to flowers, you may be able to entice these beneficial bugs to your vegetable garden by planting a few prolific bloomers among the rows of cucumbers and peppers. When the tomato worms and squash bugs show up, the assassin bugs will be ready and waiting.


Beware the Kissing Bug Bite


Although there are exceptions—such as the transmission of Chagas, a disease related to an insect known as the kissing bug—the bite of an assassin bug rarely requires medical attention. And while Chagas can come from a kissing bug bite, according to the Centers for Disease Control and Prevention, it’s most often transmitted through exposure to the bug’s feces or through the blood transmission of an infected person.

Bites from an assassin bug, however, can be very painful. The long rostrum the bug uses to kill its prey can easily pierce human skin. If you find an assassin bug on your body or clothing, flick it off sideways to remove it. Smashing it almost guarantees you’ll receive a painful bite for your efforts.