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Species Oncopeltus fasciatus - Large Milkweed Bug

Small Milkweed Bug - Oncopeltus fasciatus Large Milkweed Bug - Oncopeltus fasciatus Large Milkweed Bug - Oncopeltus fasciatus Large Milkweed Bug - Oncopeltus fasciatus Large Milkweed Bug - Oncopeltus fasciatus milkweed bug ? - Oncopeltus fasciatus LMB Nymphs - Oncopeltus fasciatus Bugs on Tropical Milkweed - Oncopeltus fasciatus
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hemiptera (True Bugs, Cicadas, Hoppers, Aphids and Allies)
Suborder Heteroptera (True Bugs)
Infraorder Pentatomomorpha
Superfamily Lygaeoidea
Family Lygaeidae (Seed Bugs)
Subfamily Lygaeinae
Genus Oncopeltus
No Taxon (subgenus Erythrischius)
Species fasciatus (Large Milkweed Bug)
Synonyms and other taxonomic changes
Oncopeltus fasciatus (Dallas)
Orig. Comb: Lygaeus fasciatus Dallas, 1852
7-8 spp. (in 2 subgenera) n. of Mex. (1)(2)
10-18 mm (adult)
Adult: overall black and orange - leathery portion of forewing with orange forward-pointing triangle anteriorly, and orange backward-pointing triangle posteriorly, separated by a black band in the middle; membranous portion of forewing black; pronotum black with orange lateral margins; freshly-molted young adults are very pale yellow, their color becoming darker and more orangish with age; adult males have a black band on the ventral side of the fourth abdominal segment; adult females have two black spots in that location
Nymph: early instars have a bright orange abdomen, developing black spots with age; later instars are more orangish-yellow; pronotum orange with black posterior margin; wingpads black, lengthening with age
Egg: oblong with three downcurved projections at tip; color initially yellow, changing to orange and then bright red before hatching
e NA to CA (CA-FL-NB-UT) (BG data)
Fields and meadows containing milkweed or dogbane
yr round in CA, TX, FL, otherwise mostly in late summer and fall (BG data)
Seeds of milkweed plants. They can be reared and fed other seeds such as sunflower, watermelon, cashew, etc.
Adults sometimes take nectar (and other plant juices).
Life Cycle
Eggs are laid in milkweed seed pods or in crevices between pods. About 30 eggs are laid a day, and about 2,000 over a female's lifespan, which lasts about a month during the summer. One or more generations per year.
They overwinter as adults. They can't survive cold winters, so they migrate south in the fall. They overwinter in the southern Atlantic and Gulf coast states where they feed and breed and gradually migrate north again in the spring and summer.
In the course of feeding these bugs accumulate toxins from the milkweed, which can potentially sicken any predators foolish enough to ignore the bright colors which warn of their toxicity.
See Also
Adults of the Small Milkweed Bug (Lygaeus kalmii) have a red "X" marking on the forewing, and a red transverse band on the pronotum, not orange lateral margins.
Small Milkweed Bug nymphs are more red than Oncopeltus nymphs, and have two diagonal black markings on the pronotum.

Adults of the Eastern Boxelder Bug (Boisea trivittata) and the Western Boxelder Bug (Boisea rubrolineatus) lack triangular orange patches on the forewing.

In the far south, other species of Oncopeltus such as the Six-spotted Milkweed Bug (O. sexmaculatus) have two large orange patches on the pronotum, whereas only the lateral margins of the pronotum are orange in the Large Milkweed Bug
Works Cited
1.American Insects: A Handbook of the Insects of America North of Mexico
Ross H. Arnett. 2000. CRC Press.
2.The Lygaeidae of Florida (Hemiptera: Lygaeidae).
Slater & Baranowski. 1990. Florida Dept. of Ag. and Consumer Services, Gainesville. xv + 211 pp.
3.Insects of North Carolina
C.S. Brimley. 1938. North Carolina Department of Agriculture.
4.Milkweed, Monarchs and More: A Field Guide to the Invertebrate Community in the Milkweed Patch
Ba Rea, Karen Oberhauser, Michael Quinn. 2003. Bas Relief Publishing Group.
5.How to Know the True Bugs
Slater, James A., and Baranowski, Richard M. 1978. Wm. C. Brown Company.