How to Identify an Assassin Bug: Types and Nymphs

Look for a narrow head that sticks out like a neck, a thick, curved beak and long legs on a slim or oval body.

• Head: long and narrow, with a groove behind the eyes that makes it look like the head sits on a neck.
• Beak: the University of Kentucky notes the beak has three segments. It is short, stout and curves under the head, ready to swing forward.
• Size: most are 1/2 to 1 1/2 inches (1.3 to 3.8 cm) long.
• Legs: long, often with thick front legs for gripping prey.
• Colour: brown, black, grey, bright green or orange with black bands, depending on the species.
• Behaviour: slow and deliberate. They wait on flowers and leaves, then grab insects that come close.

They are not beetles, even though some people call them assassin beetles. Like stink bugs, they are true bugs, with piercing mouthparts and wings that fold flat over the back.

Several kinds turn up in gardens and on porches, and colour is the quickest clue. Sizes are approximate, from the University of Kentucky and Texas A&M AgriLife.

The milkweed assassin and the pale green assassin are the slim, long legged reduviids most people find on garden plants.

• Milkweed assassin (Zelus longipes): Texas A&M AgriLife names it among the common species. It is orange to red with black markings and very long legs.
• Pale green assassin: slender and bright green, so it blends into leaves. The University of Kentucky notes Zelus species are bright green and about 3/4 inch (1.9 cm) long.
• What they eat: caterpillars, flies, beetles, aphids and other soft insects.

Despite the name, the milkweed assassin does not feed on milkweed. It hunts on many plants. The large milkweed bug, by contrast, is a plant feeder that eats milkweed seeds.

The nymphs look like small, wingless adults, often with brighter colours and very long, thin legs.

• Colour: Texas A&M AgriLife notes nymphs are often brightly coloured. Many are red, orange or green, so they stand out on leaves.
• Wings: none, only small wing pads that grow larger with each molt.
• Body shape: a narrow head and curved beak, the same as the adults.
• Behaviour: they already hunt, so you may see them holding small insects on leaves.

The biggest source of confusion is the young leaf footed bug, which is also red or orange with long legs. The comparison below shows how to tell them apart.

Check the head and the beak first. A predator holds a short, curved beak under a narrow head, while plant feeders hold a long, straight beak flat along the belly.

A few stink bugs, such as the spined soldier bug, hunt other insects too. See our stink bug guide for the common types. Squash bugs are close relatives of leaf footed bugs and also have the straight beak of a plant feeder.

Ambush bugs are small, chunky relatives that hide on flowers and grab visiting insects with thick front legs.

• Size: the University of Kentucky notes they are up to 1/2 inch (1.3 cm) long.
• Look: pale, blotchy colours that help them hide in blooms.
• Front legs: thick and grasping, similar to a praying mantis.
• Where: often on goldenrod and other late summer flowers.

They are not aggressive, but they can bite if you pick them up or press them against your skin, and the bite is painful.

• Pain: Texas A&M AgriLife describes the bite as immediately and intensely painful.
• After the bite: pain, redness and swelling at the spot that usually fade over hours to a few days.
• Can they kill humans? Garden reduviids are not known to be deadly.
• Poisonous? No. They inject saliva to digest prey, but they are not poisonous to touch.

The important exception is the kissing bug, a blood feeding relative that can carry the parasite that causes Chagas disease. See our kissing bug guide. To avoid bites, wear gloves when gardening and move them with a stick or a jar. For help with a bite, use the Bug Bite Identifier. Seek medical care for a bite with spreading redness, signs of infection or swelling of the face or throat. This information is for general education and is not medical advice.

Yes. Most are beneficial predators that eat caterpillars, beetles, aphids and other pests.

• Leave them be: they rarely cause any harm to plants or people outdoors.
• Avoid broad sprays: insecticides kill these predators along with the pests.
• Indoors: one that wanders inside can be moved out in a jar.

They live across North America in gardens, fields, woods and on porches, with the most species in warm southern states.

• Plants and flowers: milkweed, pale green and bee assassins wait on leaves and blooms.
• Trees and shrubs: wheel bugs hunt on trees and shrubs.
• Ground and debris: the black corsair hides under stones, boards and leaf litter.
• Homes: one may wander onto a porch or inside by accident, but they do not live or breed indoors.