Photo: Pale Green Assassin Bug nymph, Judy Gallagher
Judy Gallagher is an ASNV board member and a regular surveyor of local wildlife who also captures photos of what she sees, in particular the less common species.
Pale Green Assassin Bug nymph. Note the large piercing mouthpart, Judy Gallagher
Alfred Lord Tennyson famously described nature as being red in tooth and claw. So, you may not be surprised to hear that there is a family of insects called assassin bugs. There are around 7,000 species worldwide, with at least 50 species found locally. Most assassin bugs have a relatively narrow neck, sturdy build, and a long piercing mouthpart called a proboscis or rostrum.
Sinea species Spined Assassin Bug with Spotted Cucumber Beetle prey, Judy Gallagher
Predatory assassin bugs use their piercing mouthpart to inject saliva into their victim. The saliva contains proteins and other chemicals that liquify the prey's insides, and the assassin bug sucks out the liquid and feeds on it. Assassin bug saliva components vary by species. One species' saliva contains a protein that is toxic to E. coli, a bacterium that can be harmful to humans, and scientists are studying assassin bug saliva to determine if it contains other substances that could be useful to humans.
Some assassin bugs, including Spined Assassin Bug males, females and nymphs, can make sounds by drawing their proboscis back and forth through a ridged groove in the underside of their thorax. This seems to startle predators.
Pale Green Assassin Bug with prey, showing its sticky front legs, Judy Gallagher
Assassin bugs typically sit motionless waiting for prey to come to them. But some species like the Pale Green Assassin Bug have hairs called sundew setae on their front legs. The bug secretes a sticky substance onto the hairs and insects become trapped on the legs. It then pierces the hapless prey with its proboscis.
Newly hatched assassin bugs (Wheel Bug), Judy Gallagher
Newly hatched Pale Green Assassin Bugs can't yet manufacture the sticky substance needed to coat their hairs. But when the mother lays eggs, she coats each egg with viscous fluid, and the newly hatched nymphs spread the sticky substance on their legs.
Black Corsair , Judy Gallagher
Many assassin bugs lack the hairy legs that can be coated with sticky substances. The Black Corsair has protuberances on its legs to help grasp prey or grip its mate. Female Black Corsairs don't have fully developed wings, but the males can fly. They feed on insects such as caterpillars, crickets and beetles, and also sometimes eat earthworms.
Thread-legged Assassin Bug (Emesaya sp.), Judy Gallagher
Although most assassin bugs are a bit chunky, thread-legged assassin bugs are slim. They resemble walking-sticks, but are not closely related to them. They are usually nocturnal, and often steal prey from spider webs or feed on the spiders themselves.
Bee Assassin Bug with bee prey. Note the flies that are also waiting for a meal, Judy Gallagher
Many assassin bugs are generalist predators, taking any prey they can capture. They are useful biological controls in the garden. But Bee Assassin Bugs specialize in capturing bees, and there are other assassin bug species that specialize in millipedes, termites, ants or spiders.
Wheel Bug on Goldenrod, Judy Gallagher
The Wheel Bug, as its name implies, has a wheel-like structure on the top of its pronotum. It is a generalist predator, but is one of the main predators of the invasive Brown Marmorated Stink Bug. Note the pollen on its head. While Assassin Bugs are not important pollinators, it is possible!
Bloodsucking Conenose - Triatoma lecticularia, Judy Gallagher
You may have painful aftereffects for months if you are unlucky enough to be stabbed by an Assassin Bug, but they are unlikely to stab you unless you handle them. But there is one Assassin Bug subfamily that you should avoid, the Kissing bugs or Bloodsucking Conenoses. They feed on blood, including human blood, typically biting their victim on the face near the mouth or eyes. Bloodsucking Conenoses can be a vector for Chagas Disease, but thankfully we don't have that illness in our area.
Assassin bugs help keep your nuisance insects under control. Don't handle assassin bugs, but rejoice if you see them in your garden.
View more of Judy’s Observations from Meadowood articles here.