Texas Beetle Information

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Cobalt Milkweed Beetle

Chrysochus cobaltinus LeConte

Family Chrysomelidae, Subfamily Eumolpinae, Tribe Eumolpini

cf: C. auratus 

Trail Creek Cyn, White Mountains, Esmeralda Co., NV
June 12, 2005 (M Stangeland & K Davis)

Chrysochus cobaltinus State Records

Map Source: Riley et al, 2003

Range: High Plains west to California and British Columbia. (Not present in Texas.)

Adult Activity: Adults emerge in early summer and persisting in host plant patches for approximately six weeks

Larval Hosts: C. cobaltinus readily eat both Apocynum spp. and milkweeds, including Asclepias speciosa and A. eriocarpa.


Larvae are obligate root feeders, and adults eat the leaves of larval host plants. Females are highly polyandrous, males engage in extended periods of post-copulatory mate guarding.

Similar Species: This genus includes 19 species and is Holarctic in distribution (Arnett et al, 2002)

North American Taxa:

Chrysochus auratus (Fabricius) - Throughout the eastern North America, west to the Rocky Mountains
Chrysochus cobaltinus LeConte - High Plains west to California and British Columbia

Web Link:


Type Specimen:

Chrysochus cobaltinus LeConte, 1857


Arnett, R.H., Jr., M.C. Thomas, P.E. Skelley & J.H. Frank. (editors). 2002. American Beetles, Volume II: Polyphaga: Scarabaeoidea through Curculionoidea. CRC Press. 861 pp.

Cabrera-Mireles, H. 1998. Most Polyandrous Pp. 89-91 In: Walker (editor) University of Florida Book of Insect Records, University of Florida, Gainesville.

Clark, S.M., D.G. LeDoux, T.N. Seeno, E.G. Riley, A.J. Gilbert & J.M. Sullivan. 2004. Host plants of leaf beetle species occurring in the United States and Canada (Coleoptera: Megalopodidae, Orsodacnidae, Chrysomelidae exclusive of Bruchinae). Coleopterists Society, Special Publication no. 2. 476 pp.

Dickinson, J.L. 1995. Trade-offs between postcopulatory riding and mate location in the blue milkweed beetle. Behav. Ecol. 6: 280286.

Dussourd, D.E., & T. Eisner. 1987. Vein-cutting behavior: insect counterploy to the latex defense of plants. Science 237:898901.

Peterson, A. 1951. Larvae of Insects: Part II, Coleoptera, Diptera, Neuroptera, Siphonaptera, Mecoptera, Trichoptera. Edwards Bros., Inc., Ann Arbor. 416 pp.

Peterson, M.A., S. Dobler, J. Holland, L. Tantalo, & S. Locke. 2001. Behavioral, Molecular, and Morphological Evidence for a Hybrid Zone Between Chrysochus auratus and C. cobaltinus (Coleoptera: Chrysomelidae). Annals of the Entomological Society of America, 94(1): 1-9

Riley, E.G., S.M. Clark, & T.N. Seeno. 2003. Catalog of the leaf beetles of America north of Mexico (Coleoptera: Megalopodidae, Orsodacnidae and Chrysomelidae, excluding Bruchinae). Coleopterists Society, Special Publication no. 1, 290 pp.

Weiss, H.B., & E. West. 1921. Notes on insects of the spreading dogbane, Apocynum androsaemifolium L., with a description of a new dogbane midge by Dr E. P. Felt. Canadian Entomologist, 53: 146-152.

28 Aug 2008   Mike Quinn / mike.quinn@tpwd.state.tx.us / Texas Entomology / Texas Beetle Information