Hosts or Prey
Aphids, ground-dwelling invertebrates, and various other soft-bodied insects
Identification
Adult soldier beetles are elongate and usually dark brown to black with orange, red, or yellow. The head is commonly bent downward. The antennae are 11-segmented, threadlike, and commonly held forward of the body. The pronotum is usually wider than the head and wider than long. The wing covers are smooth to velvety appearing and soft and flexible, giving rise to the common name leatherwings. Adults range from 1/16 to 1-1/8 inches (1.5 to 28 mm) long, varying by species.
Larvae are elongate, cylindrical except flattened on top, and have distinct, rounded segments. In common species larvae are dark brown or dark yellowish and grow up to 3/4 inch (18 mm) long.
Lookalikes
Adults can resemble those of several other families of beetles. Lookalikes include some species of blister beetles (Meloidae), fireflies (Lampyridae), and glowworm beetles (Phengodidae).
Life Cycle
Soldier beetles develop through 4 life stages: egg, larva, pupa, and adult. Adults are relatively short lived and usually are observed only in spring through early summer. Adult females lay eggs in a mass in organic litter or topsoil. Eggs hatch in about 1 week.
Most of the life cycle is spent as ground-dwelling larvae, which can live 1 to 3 years. Overwintering is as larvae in topsoil. Pupation occurs in a cell in soil. Soldier beetles can have 1 or 2 generations per year.
Habitat
Larvae are ground-dwelling and mainly predators of eggs, larvae, and pupae of various arthropods. At least some species additionally feed on seeds and fleshy roots, but are not pests.
Adults of some species (e.g., Chauliognathus species) feed only on honeydew, nectar, and pollen. In other genera (e.g., Cantharis species) adults are also predaceous, preying on aphids and other soft-bodied Sternorrhyncha (plant-sucking insects, formerly Homoptera).
Adults are active during the day and usually observed on flowers or leaves infested with aphids or other honeydew-excreting insects. When disturbed, adults may withdraw their legs and drop to the ground as if dead. Adults' blackish and red coloration alerts vertebrate predators that cantharid beetles are distasteful; adults, larvae, and pupae can excrete noxious, defensive chemicals from specialized abdominal glands.
Species
About 160 species of soldier beetles in 11 genera occur in California. Common genera include Cantharis, Chauliognathus, and Podabrus.
More Information
- Cantharidae (Soldier Beetles), UC Irvine
- Family Cantharidae - Soldier Beetles, BugGuide, University of Iowa
- Natural Enemies Handbook, UC Integrated Pest Management Program
- Protecting Natural Enemies and Pollinators, UC Integrated Pest Management Program
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Cantharidae
