Predatory Beetles : Seven-spot lady beetles

Biology

The seven-spot lady beetle (Coccinella septempunctata) species is comparatively large (approximately 3/8 inch), with a white or pale spot on either side of the first section between the head and thorax. The body is oval and domed. The spot pattern is usually 1-4-2 (front to back), black on the orange or red wing cases. Larvae are alligator-like, dark gray with orange spots on segments 1 and 4, growing to the same length as adults. This exotic species is a relative newcomer to the Pacific Northwest, unknown before about 2000. Adults overwinter in protected sites and females may lay from 200 to more than 1,000 eggs during a period of one to three months commencing in spring or early summer. Eggs are usually deposited near prey, in small clusters of 10 to 50 in protected sites on leaves and stems. Larvae grow from 1/25 to 3/8 inch in 10 to 30 days depending on the supply of aphids. The pupal stage lasts from 3 to 12 days depending on temperature. Adults are most abundant in mid- to late summer and live for weeks or months, depending on availability of prey and time of year. One to two generations occur before adults enter hibernation. There are about 90 species of lady beetles in the Pacific Northwest. The five species most likely to be seen in Washington gardens include the transverse, convergent, seven-spot, multi-colored and mite-eating lady beetles.

Prey or Pest Targeted

• Lady beetles are industrious predators of not only aphids but also many other soft bodied arthropods like mites, thrips, insect eggs, scale insects and mealybugs.

Attracting and Keeping Natural Enemies and Pollinators in Your Yard and Garden

• Avoid regular use of synthetic, broad-spectrum pesticides. Infrequent use of certain narrow-spectrum pesticides is more compatible with some beneficials but generally the less chemical inputs there are, the greater and more diverse the beneficial insect community will be. Extensive lawns are also not conducive to attracting and retaining a diversity of beneficial insects, mites and spiders. Minimize lawn areas and maximize shrub and bush plantings. Many beneficials reside naturally in riparian and other ‘natural’ areas near to many back yards. Natural dispersion from these refuges ensures that some beneficials will visit back yards but they will not stay unless food, host and shelter resources are available. Native plants have closer affinities with native insects and therefore provide most of these resources. A garden with a good diversity of local native flora in and around back yards, will improve the abundance and diversity of local, beneficial arthropods. Native flora also provides natural overwintering sites for many beneficial insects and it is useful to leave at least a small area of native vegetation undisturbed during fall and winter.
• Some kinds of beneficial insects (e.g. lady beetles, lacewings, predatory mites) are available for purchase from commercial suppliers. However, benefits from introducing these beneficials are usually limited and short-lived. Upon release, commercially obtained lady beetles and lacewings often disperse and may rapidly leave your backyard despite the presence of prey and suitable nectar resources. Generally, it is more effective and sustainable to create a garden habitat that will be colonized by beneficials naturally.