Lady Beetles
Coccinellidae
predator · generalist predator · both
Last updated
Lady beetles are among the most recognized beneficial insects in home gardens. Both adults and larvae are voracious predators of aphids, scale insects, and mealybugs. Adults consume 50 to 60 aphids per day, while a single larva can eat 200 to 400 aphids over the course of its development. Approximately 90 species have been recorded in the Pacific Northwest, most of them native.
The convergent lady beetle (Hippodamia convergens) is sold commercially for augmentative release, though wild populations sustained through conservation practices generally provide more reliable long-term control. Avoid broad-spectrum insecticides during the growing season to protect all life stages. The spiny, alligator-shaped larvae are often more effective predators than adults but are frequently mistaken for pests and killed.
Target Pests (41)
- Aphid
- Aphid (Manzanita leafgall aphid)
- Apple Mealybug
- Apple rust mite
- Asparagus aphid
- Bean aphid
- Black cherry aphid
- Black citrus aphid
- Blister mite
- Bow-legged fir aphid
- Cyclamen mite
- Dryberry mite
- Eriophyid mite
- False spider mite
- Giant conifer aphid
- Giant willow aphid
- Grape mealybug
- Hop aphid
- Leaf curl plum aphid
- Lecanium scale
- Lettuce root aphid
- Linden aphid
- Pear psylla
- Pear rust mite
- Pearleaf blister mite
- Powdery pine needle aphid
- Prunus rust mite
- Raspberry beetle (aka Western raspberry fruitworm)
- Redberry mite
- Rose aphid
- San Jose scale
- Scale insect
- Spider mite
- Spruce aphid
- Syneta beetle
- Thrips
- Tuliptree aphid
- Twospotted spider mite
- Western flower thrips
- Woolly apple aphid
- Woolly pine needle aphid
Quick Reference
Lifecycle & Phenology
Complete metamorphosis with egg, four larval instars, pupa, and adult stage. Females oviposit clusters of 10-50 bright yellow eggs on undersides of leaves near aphid colonies. Larvae feed voraciously through four instars over 10-15 days. Pupation occurs on plant surfaces, lasting 3-12 days. Adults emerge and continue feeding. Most species overwinter as aggregated adults in leaf litter, bark crevices, or structures. Multiple generations per year in maritime PNW. Spring emergence coincides with early aphid buildup.
| Generations per Year | 2-5, depending on species and temperature (UC IPM, 2024) |
| Overwintering Stage | aggregation |
| Egg Capacity | 200-1,000+ eggs per female lifetime depending on species; H. convergens averages 200-500, Harmonia axyridis up to 1,642 (Koch, 2003; Hodek et al., 2012) |
| Larval Duration | 10-15 days through four instars at summer temperatures (UC IPM, 2024) |
| Development Duration | 20-35 days egg to adult at 20-25°C (Hodek et al., 2012) |
| Adult Lifespan | 30-90 days during active season; overwintering adults can survive several months in diapause (Hodek et al., 2012) |
| Active Months | April through October; peak activity June-August |
Habitat & Conservation
Adults and larvae require proximity to prey colonies. Adults feed on pollen and nectar when prey is scarce, requiring access to flowering plants, particularly Apiaceae and Asteraceae. Overwintering requires undisturbed leaf litter, bark, or ground cover. Reduced or no pesticide exposure is critical for population persistence.
Nectar & Pollen Sources
Pesticide Sensitivity
| Product Class | Impact | Notes |
|---|---|---|
| Neonicotinoids imidacloprid, clothianidin, thiamethoxam | lethal | Systemic uptake into pollen and nectar; lethal to foraging adults and larvae. Soil applications can persist for months (Xerces Society, 2016). |
| Pyrethroids bifenthrin, permethrin, lambda-cyhalothrin | lethal | Broad-spectrum contact toxicity; residual activity 2-4 weeks on treated surfaces |
| Carbamates carbaryl | lethal | Highly toxic to all coccinellid life stages on contact |
| Spinosad spinosad | moderate | Toxic on wet contact; low residual toxicity after drying. Less harmful than pyrethroids if applied in evening when beetles inactive |
| Horticultural oils mineral oil | low | Direct contact only; no residual. Safe for coccinellids when applied carefully with adequate drying time |
| Insecticidal soaps potassium salts of fatty acids | low | Direct contact only; no residual activity. Minimal impact on coccinellids after spray dries |
Commercial Availability
1,500-4,500 adults per 1,500 sq ft (UC IPM, 2024); commonly sold in units of 1,500 or 72,000
Dusk or early morning releases reduce dispersal; pre-watering the release area improves retention (UC IPM, 2024)
Refrigerate at 35-45°F for up to 2 weeks; longer storage reduces viability (commercial product literature)