Blue Milkweed Beetle
Chrysochus cobaltinus
Classification
- Phylum: Arthropoda
- Subphylum: Hexapoda
- Class: Insecta
- Order: Coleoptera
- Suborder: Polyphaga
- Superfamily: Chrysomeloidea
- Family: Chrysomelidae
- Subfamily: Eumolpinae
- Tribe: Eumolpini
- Genus: Chrysochus
- Species: cobaltinus
Pronunciation
How to pronounce Chrysochus cobaltinus: /ˈkrɪsoʊˌkʌs koʊˈbɔltɪnəs/
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Summary
Chrysochus cobaltinus, known as the cobalt milkweed beetle, is a leaf beetle recognizable by its vibrant blue exoskeleton and adaptation to feed on toxic milkweed plants. It participates in complex mating behaviors and has established defensive mechanisms against predators. This species plays a significant role in its ecosystem but faces challenges in terms of hybridization with closely related species.
Physical Characteristics
C. cobaltinus has an iridescent cobalt-blue exoskeleton, ranges from 6–9 millimetres (0.24–0.35 in) in length, features clubbed antennae, and has a generally oval body shape.
Identification Tips
Easily identifiable by its cobalt-blue color and association with milkweed plants.
Habitat
C. cobaltinus typically resides on milkweed plants and dogbane in the High Plains and various habitats across western North America.
Distribution
Found from British Columbia to California, Nevada, Utah, and New Mexico, particularly in areas that host milkweed and dogbane plants.
Diet
Both adults and larvae feed on dogbane (Apocynum) and milkweed (Asclepias) species, with adults damaging leaves and larvae consuming leaf tissue and occasionally roots.
Life Cycle
Adults emerge in early summer, mate, and remain on host plants for about six weeks. Females lay eggs on host leaves, and larvae develop by feeding on the plants.
Reproduction
Females exhibit high polyandry, mating with multiple males, while males engage in prolonged post-copulatory mate guarding to increase their paternity chances.
Predators
C. cobaltinus has developed defensive strategies involving the release of toxic compounds from their glands to deter predators.
Ecosystem Role
C. cobaltinus plays a role in plant dynamics by feeding on milkweed and dogbane, which may influence plant health and diversity.
Evolution
C. cobaltinus and C. auratus are sister species, showing evolutionary adaptations for cardenolide resistance, beneficial due to their toxic diets.
Similar Taxa
Tags
- Cobalt Milkweed Beetle
- Chrysochus cobaltinus
- entomology
- beetles