# Small milkweed bug (Lygaeus kalmii) > A small red-orange and black seed-feeding bug commonly found on milkweed; harmless to people and mostly a seed predator of milkweed plants. Source: https://insectscanner.com/species/small-milkweed-bug/ (updated 2026-10-10) ## Is it dangerous? **Non-toxic.** Small milkweed bugs do not have a medically important bite or sting. They may give a mild, brief bite if handled roughly, which can be slightly irritating but is not dangerous. Wash the area with soap and water if bitten and treat any mild irritation with standard first aid. **Pets:** Not known to be toxic to pets. Because they may taste bad (sequestered milkweed compounds), pets usually avoid eating them; ingestion could cause mild gastrointestinal upset in sensitive animals. ## Quick facts - Scientific name: Lygaeus kalmii - Order: Hemiptera (True bugs, cicadas, hoppers) - Family: Lygaeidae (Seed bugs) - Size: 10-12 mm long - Colours: Orange-red, Black, White (small wing spot), Dark brown (legs/antennae) - Habitat: Meadows, roadsides, fields and gardens where milkweed (Asclepias) and similar plants grow; sometimes edges of woodlots and disturbed ground. - Range: Widespread across much of North America, from southern Canada through the United States. - Active: Active from late spring through autumn, peak abundance in summer and early fall; diurnal (active by day). - Lifespan: Adults live through the summer into autumn; some adults overwinter and can live up to several months depending on conditions. - Effect on plants: Seed predator - Pest: no ## Overview Lygaeus kalmii is a moderately common true bug that feeds primarily on the seeds of milkweed and related plants. Adults and nymphs congregate on milkweed pods and flowers during summer and autumn. They are not dangerous to people — they do not have a medically significant bite or sting — and are generally considered a natural specialist of milkweed seed pods. These bugs are often seen in gardens, meadows, roadsides and fields where milkweed grows. They may occasionally wander into buildings in autumn while seeking overwintering shelter, but they do not infest homes or reproduce indoors. ## How to identify it Adults are about 10-12 mm long and mostly black with a bold red-orange X-shaped band across the forewings. The head is black with a red spot, and the pronotum is red-orange at the front with black behind. The black wing membrane has white spots, a useful diagnostic mark. Legs and antennae are black. Nymphs are wingless and bright orange-red with black markings; later instars develop black wing pads. - Black body with a red-orange X-shaped band across the back and white spots on the black wing membrane. - Adult length about 10-12 mm; nymphs are wingless and bright orange-red with black markings. - Found congregating on milkweed seed pods and flowers during summer and fall. - Smaller and with a white wing-spot compared with the larger Oncopeltus (large milkweed bug). ## Lookalikes - **Large milkweed bug** (Oncopeltus fasciatus): Larger (about 10-18 mm) and orange with broad black bands across the back rather than a red X; lacks white spots on the wing membrane. - **Milkweed assassin bug** (Zelus longipes): Predatory and more elongate with raptorial front legs; not the red-and-black seed-feeding pattern of Lygaeus kalmii. ## Life cycle - **Egg:** Females lay clusters of small elongated eggs on stems, leaves or near seed pods of host plants. Eggs hatch in about 1-2 weeks depending on temperature. - **Nymph (immature):** Nymphs pass through several instars. Early instars are wingless and bright orange-red; later instars develop black markings and wing pads. Nymphs feed on developing seeds and pods. - **Adult:** Fully winged adults appear after the final molt. Adults mate and continue feeding on seeds; some survive to overwinter in sheltered places. ## Diet and predators - Young eat: Feed primarily on seeds and fluids from milkweed seed pods and developing seeds; may also feed on other seeds and plant juices. - Adults eat: Mainly milkweed seeds and other dry seeds; sometimes nectar and plant sap. - Predators of the young: Spiders, predatory insects (assassin bugs, mantids), and some birds; however the bugs can be distasteful due to milkweed compounds. - Predators of adults: Birds, spiders and predatory insects; bright colors and sequestered plant toxins reduce predation by some predators. ## Effect on plants and gardens Adults and nymphs feed on seeds of milkweed and related plants by piercing seed pods and sucking out contents. Heavy local feeding can reduce seed production but usually does not kill plants or seriously harm wild milkweed populations. ## Where and when to find it Look on milkweed plants (Asclepias) — seed pods, flowers and stems — in meadows, roadsides and gardens. Nymphs and adults are both found on the same plants. - Best time: Summer through early fall, during daylight hours when plants are warm and seeds are maturing. - Tips: Approach slowly and photograph from the side to capture the dorsal pattern; check seed pods and the undersides of leaves for nymphs. ## Fun facts - They concentrate on milkweed seeds and can be seen in groups on pods as the seeds mature. - Their bright colours warn predators that they are unpalatable after feeding on milkweed chemicals. - Nymphs and adults look similar in colour, making them easy to spot throughout development. ## Frequently asked questions ### Do small milkweed bugs bite? They are not aggressive; a bite is rare and only a mild, brief annoyance if you handle them roughly. No medical treatment is normally required. ### Are small milkweed bugs harmful to my garden plants? They mainly eat milkweed seeds. They rarely harm the health of the plant; the main effect is reduced seed set if many bugs feed on pods. ### Why are there so many on my milkweed? They congregate where seeds are available. A single milkweed patch with many pods is an attractive feeding and breeding site. ### How do I get rid of small milkweed bugs? If control is desired, handpick and remove bugs or shake pods into a bucket of soapy water, or use a vacuum. Insecticidal soaps and pyrethroid sprays will reduce numbers but also affect beneficial insects. Removing seed pods reduces food and breeding sites. ### Will they come into my house in autumn? They sometimes wander into shelters while seeking overwintering sites but do not infest homes. Seal gaps and screens to prevent entry and remove bugs if they appear indoors. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/62045), [Wikipedia](https://en.wikipedia.org/wiki/Lygaeus_kalmii). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.