Hosts or Prey
Aphids and psyllids especially but also various other soft-bodied insects, such as whiteflies
Identification
All stages of the ashy gray lady beetle (ladybug or ladybird beetle) occur openly on plant leaves and stems. The adult is 1/6 to 1/4 inch (4–6 mm) long and oval to rounded when viewed from above and dome shaped (convex) when viewed from the side. The thorax and wing covers of adults are commonly gray or pinkish gray with more than a dozen black spots. There is also a form that is black with two red spots and another form that is gray with a large black blotch on each wing cover plus several small black spots.
The oblong eggs are yellowish and about 1/25 inch (1 mm) long. They occur in irregular groups. Larvae resemble tiny alligators with distinct segments and long legs. First instars (larvae) are black and about 1/16 inch (1.5 mm) long. Later instars are blackish with whitish and yellow markings. The fourth (last) instar is about 5/16 inch (7 mm) long.
The convex, rounded pupa is mostly gray with black spots. As it ages, distinct appendages develop folded against the body.
Lookalikes
Several other lady beetle species in California resemble the O. v-nigrum form that is black with two red spots. These include Axion plagiatum, Chilocorus cacti, C. fraternus, C. kuwanae, and the twicestabbed lady beetle (C. orbus).
Unlike ashy gray lady beetle, on the adults of the Axion and Chilocorus species the margins of the wing covers flair outwards as a distinct ridge. Adults of these other species also lack the pale (gray to whitish) coloration that is on both the head and thorax of the various color forms of ashy gray lady beetle. Larvae of the lookalikes are spiny unlike the relatively smooth surface on larvae of ashy gray lady beetle.
Life Cycle
Lady beetles develop through 4 life stages: egg, larva, pupa, and adult. Adult females lay eggs on their end in a loose group of about 1 to 3 dozen. The first instars are relatively inactive and commonly feed on and remain near the empty shells of eggs from which they hatched. Larvae develop through 4 increasingly larger instars before pupating openly on plant foliage or stems.
Development time from an egg to a reproductive adult is about 3 weeks when temperatures average 77ºF. Olla v-nigrum has multiple generations per year.
Habitat
Ashy gray lady beetle occurs mostly in trees and shrubs including in fruit tree and nut crops, landscape trees and shrubs, and woody wildland plants. To improve biological control
- Control ants because they attack lady beetles and other natural enemies of various pests.
- 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. Olla v-nigrum is the only Olla species reported in the United States. Three Olla species that closely resemble the gray and black-spotted forms of O. v-nigrum occur in Central America, South America, or Mexico but these lookalikes have not been reported in the United States.
More Information
- The California Beetle Database, Santa Barbara Museum of Natural History
- The Coccinellidae (Coleoptera) of America North of Mexico, Journal of the New York Entomological Society
- Revision of the New World Lady Beetles of the Genus Olla and Description of a New Allied Genus (Coleoptera: Coccinellidae), UC Berkeley, Annals of the Entomological Society of America
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Coccinellidae
