Predatory Beetles : Transverse lady beetles

Biology

The transverse lady beetle (Coccinella transversoguttata) adult is approximately ¼ inch long and rounded. The wing covers (elytra) are orange-red with distinct, narrow transverse black markings. The body and pronotum (area between the head and wing cases) are black with small white or yellow patches. The yellowish-orange, elongated eggs are laid upright in batches. The alligator-shaped larva is purple-blue with orange markings. Transverse lady beetles are native to North America but appear to be declining in abundance. In some years, C. transversoguttata is common, but more frequently it is scarce; the cause of this population decline is unknown. Adults may consume up to 100 aphids or mites a day depending on temperature. Larvae are also voracious feeders. When prey is scarce adults can survive (but not reproduce) on nectar, honeydew, and pollen. Larvae molt through four instars before pupating. The life cycle from egg to adult takes approximately 3-4 weeks during summer. 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.