Hosts or Prey
Scale insects mostly
Identification
The adult lady beetle (ladybug or ladybird beetle) is metallic dark blue, green, or purple and about 1/8 to 1/6 to inch (3–4 mm) long. Females are uniformly dark. Males have orange or yellow on the head and outer margins of the pronotum. Adults are round when viewed from above and dome shaped (convex) when viewed from the side. They have a distinct outward flare (ridge) on the bottom margins of the wing covers.
Eggs are a little less than 1/25 inch (1 mm) long. They are football shaped, pale orange to yellow, and laid on end in a loose group. Larvae have numerous short, branched, spines. They are pale yellow to whitish and about 1/25 inch (1 mm) long when they hatch. As they age, larvae develop blackish to dark gray blotches on top the abdomen and rear portion of the thorax. Mature larvae are about 1/5 to 1/4 inch (5–6 mm) long.
Pupae are about 1/5 inch (5 mm) long. They occur within the blackish and whitish, spine-covered skin of the last instar. When the skin of the last instar (puparium) splits open to reveal the pupa, the pupa is initially pale but darkens as it ages and develops appendages folded against the body.
Lookalikes
Exochomus metallicus is a dark metallic blue lady beetle that is also about 1/8 to 1/6 to inch (3–4 mm) long. It was introduced into California from Ethiopia in 1954 to control black scale and citricola scale. Both E. metallicus and H. chalybeus can occur together in at least coastal counties of Central and Southern California. Unlike the smooth, hairless surface of steelblue lady beetle the adults of E. metallicus are covered with fine, short hairs.
Life Cycle
Lady beetles develop through four life stages: egg, larva, pupa, and adult. Adult females lay eggs on plants near prey, mostly near various species of scale insects. After hatching larvae develop through four increasingly larger instars. At maturity larvae pupate openly on plant parts.
Adults eat about 1 dozen scales per day and larvae each consume about 10 scales per day, varying by the size of the hosts and lady beetle. Adults commonly overwinter in aggregations in protected places, such as organic litter on the ground or in lower portions of plants with a dense canopy.
Egg to reproductive adult development time is about 5 weeks when temperatures are warm. The steelblue lady beetle has several generations per year.
Habitat
Halmus chalybeus (then incorrectly named Orcus chalybeus) was introduced from Australia into Southern California in 1892 for the biological control of mealybugs and scale insects infesting citrus. It now occurs in at least coastal areas of Central and Southern California.
Its prey is mostly scales including armored scales, eriococcids, and soft scales. It also feeds on other plant-sucking insects formerly called Homoptera, such as aphids and psyllids.
To improve biological control
- Control ants because they attack lady beetles and other natural enemies.
- Grow flowering insectary plants to provide nectar and pollen to feed adult natural enemies.
- Reduce dustiness that disrupts the activities of natural enemies (e.g., periodically hose off small plants).
- Avoid the application of broad-spectrum, persistent insecticides for all pests because they are toxic to natural enemies.
See Protecting Natural Enemies and Pollinators for more information.
Species
At least 191 species of lady beetles occur in California. Halmus chalybeus is the only member of its genus reported in the United States.
More Information
- The Coccinellidae (Coleoptera) of America North of Mexico, Journal of the New York Entomological Society
- Halmus chalybeus (Boisduval), Ladybirds of Australia, CSIRO
- Species Halmus chalybeus - Steelblue Lady Beetle, BugGuide, Iowa State University
- Steelblue Ladybird - Halmus chalybeus, New Zealand Factsheets
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Coccinellidae
