The Assassins

Kelly’s Field Notes

Common Name: Assassin bugs, Ambush bugs (subfamily Phymatinae), Thread-legged bugs (Sunfamily Emesinae), Kissing bugs (subfamily Triatominae), Wheel bugs (genus Arilus), Grass assassin bugs (genus Lopodytes)  

Order: Hemiptera

Family: Reduviidae (the largest predatory family of Hemiptera, the true bugs)

Genus: There are 981 genera within family Reduviidae

Species: There are almost 7,000 species of Reduviidae

Notable species:

• Acanthaspis pedestris - this species and others in genus Acanthaspis camouflages itself with the corpses of their ant prey. Scientists speculate the ant pile changes the shape of the assassin bug nymph, confusing highly visual predators like jumping spiders (which were used in an experiment to test this hypothesis).

• Masked Hunter (Reduvius personatus) - this species camouflages itself with dust. They feed on pests and are sometimes kept as pets.

• Winchuka (Triatoma infestans) - this and other species of subfamily Triatominae are called kissing bugs, they can spread Chagas disease. It is speculated that Chagas disease from this species killed Charles Darwin. Darwin described the bite in his journal while on the beagle survey voyage as he “experienced an attack, & it deserves no less a name, of the Benchuca, the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over one's body; before sucking they are quite thin, but afterwards round & bloated with blood, & in this state they are easily squashed.”

• Subfamily Ectrichodiinae specialize in preying upon millipedes. This subfamily also exhibits sexual dimorphism and aposematistm, both uncommon in other reduviids.

• Feather-legged bugs (subfamily Holoptilinae) - these little guys have legs covered in fine setaes (hairs) and specialize in eating ants. They have trichomes (hairs attached to glands) on their abdomens that attract ants. While adults eat ants as they come, nymphs wait for the ants to bite the trichomes before piercing them in the head with its proboscis.

• Subfamily Phymatinae also called ambush bugs are sit and wait predators! They are stouter and squattier than their on the move cousins and have camouflage that blends into the flowers they hang out on.

• Subfamily Emesinae also called thread-legged bugs are often confused for stilt bugs (Berytidae) as they look less like their assassin bug cousins and more like stilt bugs with their long legs and elongated bodies.

• Genus Arilus also called wheel bugs have very cool looking crests on their pronotum (the upper part of the thorax). Scientists are not quite sure what the purpose of the wheel is, but it has been speculated to be a predator deterrent and/or a form of species recognition.

Description: 

Adult Reduviidae have elongated heads with fairly long bodies, about 1.2 to 3.6 cm in length (0.47 to 1.42 in). Their wings are folded over their backs. Long legs are also a common characteristic of this family. They range in colors from green, to red, to orange, sometimes speckled. Adults have long proboscises they use to drink hemolymph, the insect equivalent to blood, from their prey. But it also has a second use! The proboscis fits into a groove in the thorax. When threatened by predators, the adult can rub the proboscis along the ridges in the groove to produce sound (stridulation). While most assassin bugs can fly, females of genus Melanolestes have stunted non-functional wings - they tend to patrol the ground.

Nymphal assassin bugs are smaller than adults, with pronounced tiny little heads, long legs, and no wings. They are often brown, black, or reddish-orange in color, with lighter or darker patterns overlaid upon the main color. Many species have adaptations to hide from predators.

A Note About Leaf-footed Bugs: 

Leaf-footed bugs may look very similar to assassin bugs, but they are not closely related! Leaf-footed bugs belong to family Coreidae. Leaf-footed bugs are more closely related to stink bugs than they are assassin bugs.

Life Cycle: 

All members of order Hemiptera (true bugs) go through simple metamorphosis - egg, nymph, adult. Females lay their eggs on the undersides of leaves in warmer months. Once the eggs hatch the nymphs are off to hunt and grow. They will have 4 to 7 molts, depending on species, before becoming adults. Depending on species, adults may overwinter tucked away between tree bark and other shelter (similar to ladybugs).

Chagas Disease:

Chagas disease is caused by the parasite Trypanosoma cruzi. It is primarily found in Central and South America, though cases have also been reported in the United States and Europe. The main mode of transmission is through contact with the feces of triatomine bugs, (kissing bugs, vampire bugs, conenose bugs). These mainly nocturnal insects feed on vertebrate blood (over 150 species of vertebrates). After feeding, they defecate near the site of the bite, and the parasite can enter the body when the person scratches or rubs the area. As of 2019, 6.5 million people were infected with Chagas disease, which resulted in 9,490 deaths. Chagas disease was first described by Carlos Chagas in 1909.

Chagas disease has two stages, an acute stage and a chronic stage. The acute stage occurs two weeks after the bite. While often asymptomatic, one can experience headaches, fever, tiredness, swollen lymph nodes, and a swollen nodule at the bite site. In very rare cases, acute symptoms may be enlargement of the spleen and/or liver or inflammation of the brain. The chronic stage can also be asymptomatic or pretty terrible resulting in eventual heart or digestive system failure. This may occur in 20-30% of infected people.

Chagas disease can also be transmitted through blood transfusions, organ transplants, and from mother to child. There are currently no vaccines. We recommend checking out the episode of This Podcast Will Kill You on the subject.

Super Powers:

• Stabby Stabby - the proboscis of assassin bugs is used to pierce prey or stab predators. Venom and/or digestive fluids are injected after penetration.

• Warning Sounds - using the proboscis and a groove in the thorax, adult assassin bugs can create sound to deter predators.

• Camouflage - nymphs of genus Acanthaspis cover themselves with ant corpses to confuse predators. Members of subfamily Phymatinae also have excellent camouflage to blend into flowers, where they sit and wait for prey to come to them. Reduvius personatus nymphs cover themselves with small debris to hide in plain sight.

• Raptorial Forelegs - members of subfamilies Phymatinae and Emesinare have lightning fast forelegs, much like a preying mantis.

• Flight - most assassin bugs can fly, but they are pretty bad at it. They are meant more for short bursts than actual sustained flight. The exception to this is the bee assassin (Apiomerus crassipes) which is an excellent flier. They patrol flowering plants bees are visiting.

• Pest Control - assassin bugs are now being used as biocontrol agents, protecting our crops from pests.

References:

“Assassin Bugs & Ambush Bugs of Kentucky.” University of Kentucky Entomology, www.uky.edu/Ag/CritterFiles/casefile/insects/bugs/assassin/assassin.htm.

“Assassin Bugs / UC Statewide IPM Program (UC IPM).” UC IPM, 2015, ipm.ucanr.edu/natural-enemies/assassin-bugs/#gsc.tab=0.

‌‌CDC. “Chagas Disease.” U.S. Centers for Disease Control and Prevention, 26 Apr. 2024, www.cdc.gov/chagas/index.html.

“Chagas Disease.” Wikipedia, 18 Nov. 2019, en.wikipedia.org/wiki/Chagas_disease.

“Ectrichodiinae.” Heteropteran Systematics Lab, 13 July 2023, heteroptera.ucr.edu/assassin-bugs/ectrichodiinae. Accessed 17 May 2025.

Li, Hu, et al. "Mitochondrial phylogenomics of Hemiptera reveals adaptive innovations driving the diversification of true bugs." Proceedings of the Royal Society B: Biological Sciences 284.1862 (2017): 20171223.

‌“Masked Hunter.” Penn State Extension, extension.psu.edu/masked-hunter.

‌“Reduviidae.” Wikipedia, 31 Oct. 2022, en.wikipedia.org/wiki/Reduviidae.

Stromberg, J. “This Insect Uses Its Victims’ Carcasses as Camouflage.” Smithsonian Magazine, www.smithsonianmag.com/science-nature/this-insect-uses-its-victims-carcasses-as-camouflage-83656246

“Triatoma Infestans.” Wikipedia, 9 Mar. 2025, https://en.wikipedia.org/wiki/Triatoma_infestans

Weirauch, Christiane, and Gerasimos Cassis. "Attracting ants: The trichome and novel glandular areas on the sternum of Ptilocnemus lemur (Heteroptera: Reduviidae: Holoptilinae)." Journal of the New York Entomological Society 114.1 (2006): 28-37.

“Wheel Bug, Arilus Cristatus” Loyola University Center for Environmental Communication, lucec.loyno.edu/natural-history-writings/wheel-bug-arilus-cristatus.

‌‌Ye, Fei et al. “Mitochondrial Genomes from Two Specialized Subfamilies of Reduviidae (Insecta: Hemiptera) Reveal Novel Gene Rearrangements of True Bugs.” Genes vol. 12,8 1134. 26 Jul. 2021, doi:10.3390/genes12081134