Hosts or Prey
Soft-bodied insects, insect eggs, and especially aphids
The adults (also called ladybugs or ladybird beetles) are dome shaped (convex) on top, flat on the bottom, and oblong when viewed from above. The hard, shiny body is 1/6 to 1/4 inch (4–7 mm) long. The head has short, clubbed antennae and chewing mouthparts, which commonly are pointed downward and may not be apparent when viewed from above.
Adult wing covers are orange and commonly have 13 black spots. Some individuals have fewer spots or no spots. The thorax is black with a white margin. The species is named for the two distinct white markings on the thorax that are angled towards each other (convergent markings).
Eggs are oblong, yellow, and about 1/25 inch (1 mm) long. They are laid on end in clusters of about 10 to 30 on leaves and green stems near aphids or other prey.
Larvae are active with long legs and resemble tiny alligators. They grow up to 1/4 inch (6 mm) long and are blackish with orange blotches that become more prominent on older instars.
Pupae are 1/5 inch (5 mm) long and glued to plant parts near where they fed as larvae. They initially are orange, but increasingly develop black blotches prior to adult emergence.
Numerous species of aphid-feeding lady beetles are orange with black spots. Most other lady beetles are more rounded when viewed from above, not distinctly oblong as with Hippodamia species. Unlike all other lady beetles, Hippodamia species have cleft (split, two-pointed) tarsal claws at the end of each foot.
At least ten species of Hippodamia in California have forms with converging white bars on the thorax. Hippodamia quinquesignata quinquesignata and Hippodamia quinquesignata ambigua have forms with black spots on orange wing covers and converging white marks on the thorax and cannot be reliably distinguished from convergent lady beetle based on external appearance. The species are reliably distinguished only by expert dissection and examination of male genitalia.
Lady beetles develop through four life stages: egg, larva, pupa, and adult. Adult females can lay several hundred eggs during their growing-season lifespan of about two months. After hatching, larvae develop through four increasingly larger instars.
Overwintering is in aggregations, commonly on low-growing vegetation at moist locations. A large portion of the California populations overwinter in foothills of the Coastal Range or Sierra Nevada. These adults migrate to the Coastal Range or Sierra in summer from coastal and valley locations, then in late winter migrate back to lower elevations. Convergent lady beetle has two or more generations per year in California.
The convergent lady beetle can be found in almost any habitat where plants are infested by aphids. Adults are good fliers and readily migrate among plants and locations.
Young lady beetle larvae usually pierce and suck the contents from their prey. Older larvae and adults chew prey and can consume the entire insect.
Convergent lady beetle adults are sold for release to control aphids. Commercially available Hippodamia are field collected from their overwintering sites using portable vacuum devices. These beetles are available for purchase via shipping services and from some retail garden stores.
Although resident lady beetles are important predators, purchased Hippodamia inherently disperse. Most will fly away from the release site within 1 or 2 days after they are released even if aphids are plentiful. However, each adult can consume about 100 aphids per day before it disperses.
Controlling aphids on roses can require about 1,500 beetles per shrub released at 1- to 2-week intervals as long as conditions are suitable for aphids. You may need to plan in advance and purchase the beetles through a shipping service to obtain large numbers of them when needed and for a reasonable price. If beetles are stored in the refrigerator (do not freeze them) and released periodically, warm beetles weekly to room temperature and feed them very dilute sugar water by misting them using a trigger-pump spray bottle. Do not refrigerate the lady beetles with food as they excrete an unpleasant odor.
To increase the effectiveness of resident natural enemies and any that are released
- Avoid the use of broad-spectrum, persistent insecticides and miticides (acaricides).
- Control ants and dust.
- Grow flowering plants that provide nectar and pollen for adults (insectary plants).
Wetting plants first and releasing beetles on the ground near the trunk and beneath plants in the late evening when it is cooler may slow beetle dispersal. See Lady Beetle Releases for Aphid Control: How to Help Them Work (PDF), Natural Enemy Releases for Biological Control of Crop Pests, Protecting Natural Enemies and Pollinators, and Vendors of Beneficial Organisms in North America for more information.
About 150 species of lady beetles occur in California. These include at least 17 Hippodamia species, of which Hippodamia convergens is the most common. Although some other Hippodamia species closely resemble the convergent lady beetle others have a different appearance. For example the sinuate lady beetle, Hippodamia sinuata, resembles the western striped cucumber beetle, a plant-feeding pest.
- The Coccinellidae (Coleoptera) of America North of Mexico, Journal of the New York Entomological Society
- Convergent Ladybird Beetle, Hippodamia convergens, UC Irvine
- Interactions Among Convergent Lady Beetle (Hippodamia convergens) Releases, Aphid Populations and Rose Cultivar (PDF), Biological Control
- Lady Beetle Releases for Aphid Control: How to Help Them Work (PDF), UC Retail Nursery & Garden Center IPM News
- Natural Enemies Handbook, UC Integrated Pest Management Program
- Protecting Natural Enemies and Pollinators, UC Integrated Pest Management Program
- Phylum: Arthropoda
- Class: Insecta
- Order: Coleoptera
- Family: Coccinellidae