- Transverse Lady Beetle doing its thing: pigging out on aphids.
That's OK; that's what lady beetles do - eat pestiferous insects that cause great harm to Monarch caterpillar food and the agricultural and landscaping business.
The problem is, as is often the case with the way Man does things, if a little is good, we think that a whole lot more is better - like pesticides. Not so with lady beetles. Unfortunately, the free enterprise system that we all operate within, depend on to make a living and find things in the grocery store got carried away with ladybugs.
There are hundreds of sites advertising lady beetles for "natural control" of agricultural pests, with pitches like:
"LIVE LADYBUGS In stock and ready to ship! Ladybugs are general predators that feed on a variety of slow-moving insects including aphids, moth eggs, mites, scales, thrips, leafhoppers, mealybugs and other slow-moving insects. Ladybugs are a must-have for organic gardening or organic farming. A ladybug eats insects during both the adult and larval stages, so you can buy ladybugs as adults and continue to have live ladybugs eating through other parts of their life cycle as they reproduce."
Isn't that wonderful! Just release the little buggers and your aphid problems are solved, and the best part is you DO NOT HAVE TO SPRAY, or at least shouldn't.
There are a few problems, however. Commercial collectors distribute beetles that have been "harvested" from natural winter aggregation sites. If lady beetles are collected in the dormant state and transported for field release, even among yummy aphid infestations, they usually migrate before feeding and laying eggs. But there's an even more serious problem: The beetles you paid good money for may be parasitized. If that's the case, then you are introducing parasites from some other place (Brazil, for example) that have no known control in Oregon.
Most lady beetles in North America are beneficial as both adults and larvae, feeding primarily on aphids, mites, small insects and insect eggs. However, the two exceptions are the introduced Mexican bean beetle and the squash beetle. The adults and larvae of both species feed only on plants, the same ones being eaten by the aphids that the lady beetles supposedly are trying to help you eliminate.
Then there's the real "stinker," the Asian lady beetle. Although lady beetles are an effective biological control agent in agricultural and landscape environments, this bug has become a major nuisance to homeowners because of its habit of invading houses and buildings in multitudinous numbers while searching for protected sites to over-winter. When you're ready to start using biological controls, do your homework BEFORE you buy. You'll be happy you did, and so will your garden's ecosystem.