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How to identify it
- The black and red (orange) coloring is distinctive, though highly variable: the usual form has alternating orange and black areas on the back, an orange or reddish-brown belly with each segment black at the front, and black legs with two yellow rings.[2]
- Females run about 15 to 18 mm long and males about 14 to 18 mm, roughly 1/2 to 3/4 inch, with a slender body, slender legs and a long, cylindrical head.[2]
- The rear corners of the shoulder plate (pronotum) are rounded, without spines, and the front part of the shoulder plate is raised; together with size and color, these separate it from similar species.[2]
- Like other assassin bugs it has stout, curved, strawlike mouthparts used to stab prey.[1][6]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Large milkweed bug | Some color forms of the milkweed assassin bug may mimic the milkweed bug. The assassin bug has a long, narrow head with a stout beak, a slimmer body and longer, slender legs.[2][1] |
| Pale green assassin bug and other Zelus | Several Zelus species live in Texas, and Texas A&M calls the milkweed assassin bug the most distinctive of them. The pale green assassin bug is green, with a pair of spines on the back corners of the shoulder plate; the milkweed assassin bug's corners are rounded.[1][6][2] |
Where it lives
The southern US, Mexico, Central America, the Caribbean, northern South America, Paraguay and southern Brazil. Texas A&M lists it among the most common assassin bugs around Galveston County. GBIF's US records since 1990 come mainly from Florida and Texas, then Louisiana, the Carolinas, Georgia, Alabama and Mississippi, with fewer from California.[2][1][8]
Biology and life cycle
Assassin bugs catch prey with a quick stab of the beak, inject a paralyzing venom that liquefies the prey's tissues, and suck up the fluids.[1][6]
It is a generalist predator. In south Florida sweet corn it hunts the picture-winged flies whose maggots damage ears, eating about five flies a day in lab feeding tests.[3]
In those Florida corn fields the bugs moved up the plant over the day with their prey: low and middle leaves in the morning, ears at midday and the top and tassel by late afternoon.[3]
In lab tests with fall armyworm caterpillars it attacked small, medium and large larvae equally often but succeeded more often with small ones, and given a choice it mostly killed the small ones, probably because bigger prey risks injury.[4]
Genus-wide, Zelus assassin bugs don't stick to particular host plants, which fits their generalist hunting.[2]
Damage and signs
- It does not feed on plants. Texas A&M describes assassin bugs as predatory insects of great benefit to gardeners.[1]
Health risk
It can deliver a painful bite if handled carelessly; Clemson says the pain comes from toxic saliva the bug uses to digest prey, and the Missouri Department of Conservation says crushing or slapping at assassin bugs usually causes them to bite. For an insect bite, MedlinePlus advises washing the site with soap and water, applying ice wrapped in a washcloth 10 minutes on and 10 minutes off, and watching over the next several days for signs of infection. Call 911 for trouble breathing, throat tightness, or swelling of the face or mouth.[5][6][7]
Control
Prevention
No control is needed. Texas A&M recommends against controlling assassin bugs in gardens because they are beneficial predators that are seldom abundant enough to need spraying.[1]
To avoid a bite, don't pick one up or slap at it; if one lands on you, brush it off.[1][6]
As a natural pest control
Florida corn researchers call it a promising biological control agent for picture-winged flies, though its numbers can vary between seasons. Texas A&M notes that assassin bugs are generally not very abundant.[3][1]
Common questions
- Is the long-legged orange and black bug on my plants a milkweed bug?
- It may be a milkweed assassin bug, a predator whose color forms may mimic the milkweed bug. The assassin bug has a long, narrow head, a stout beak and long, slender legs.[2][1]
- Does the milkweed assassin bug bite?
- It can if you handle it carelessly or crush it against your skin, and assassin bug bites are painful. Wash the bite, use a cold pack, and get emergency help for trouble breathing or facial swelling.[5][6][7]
- What does the milkweed assassin bug eat?
- Other insects. Assassin bugs take bugs, bees, flies and caterpillars, and studies of this species show it eating picture-winged flies in corn and fall armyworm caterpillars.[1][3][4]
Sources
- Texas A&M AgriLife Extension Service, “Wheel bugs and other assassin bugs, ENT-1003 (M. Merchant).” citybugs.tamu.edu/factsheets/landscape/others/ent-1003/ (accessed 2026-11-11)
- Biodiversity Data Journal (Pensoft), “A taxonomic monograph of the assassin bug genus Zelus Fabricius: 71 species based on 10,000 specimens (Zhang, Hart & Weirauch 2016), Zelus longipes account.” doi.org/10.3897/BDJ.4.e8150 (accessed 2026-11-11)
- Environmental Entomology, via PubMed, “Distribution of Zelus longipes in south Florida corn fields and its functional response to corn-infesting picture-winged flies (Kalsi et al. 2014).” pubmed.ncbi.nlm.nih.gov/25203811/ (accessed 2026-11-11)
- Journal of Applied Entomology (Wiley), via Crossref, “Influence of prey size on predation success by Zelus longipes L. (Cogni, Freitas & Amaral Filho 2002), abstract.” doi.org/10.1046/j.1439-0418.2002.00593.x (accessed 2026-11-11)
- Clemson Cooperative Extension Home & Garden Information Center, “Assassin Bugs (HGIC 2472).” hgic.clemson.edu/factsheet/assassin-bugs/ (accessed 2026-11-11)
- Missouri Department of Conservation, “Assassin Bugs, Field Guide.” mdc.mo.gov/discover-nature/field-guide/assassin-bugs (accessed 2026-11-11)
- MedlinePlus, U.S. National Library of Medicine, “Insect bites and stings (Medical Encyclopedia).” medlineplus.gov/ency/article/000033.htm (accessed 2026-11-11)
- Global Biodiversity Information Facility (GBIF), “Zelus longipes: US occurrence records since 1990 by state (GBIF occurrence search API).” api.gbif.org/v1/occurrence/search?taxonKey=2008843&country=US&hasGeospatialIssue=false&occurrenceStatus=PRESENT&year=1990%2C2026&facet=stateProvince&facetLimit=400&limit=0 (accessed 2026-11-11)
- iNaturalist, “Zelus longipes taxon page (order and family).” www.inaturalist.org/taxa/133826 (accessed 2026-11-11)