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Should I Purchase Ladybugs to Release in My Garden?

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Commercial sellers collect ladybugs from their overwintering sites.

Commercial sellers collect ladybugs from their overwintering sites, where they aggregate in large groups. The ladybugs are marketed to gardeners as an organic pest control. But does releasing ladybugs work?

Scott Bauer, USDA Agricultural Research Service, Bugwood.org
Question: Should I Purchase Ladybugs to Release in My Garden?

I've seen catalogs where you can purchase ladybugs to control the aphids and other pests in your garden. This sounds like a good alternative to using pesticides, so I'm thinking of releasing beneficial ladybugs in my home garden. Does this work, and how do I do it?

Answer:

Great question. In general, releasing ladybugs in a home garden is not very effective for controlling aphids or other small insect pests. Beneficial insect releases work well in greenhouses, where the environment is enclosed and they can't just fly away. But in the home garden, ladybugs have a tendency to disperse.

Here's the problem. Commercial vendors collect the ladybugs during the winter or early spring, when the beetles have aggregated in large numbers at their overwintering sites. They keep the ladybugs inactive by refrigerating them until it is time for shipping.

In their native environment, the ladybugs become active again as temperatures rise. When spring weather arrives, the first thing they do is disperse to find food. So, when vendors ship these ladybugs, still groggy from their winter diapause, they are genetically programmed to disperse. And they will, unless you do something to make them stay.

Some catalogs sell "preconditioned" ladybugs, which means the ladybugs have been fed prior to shipping. This makes them less likely to disperse upon release, so if you are going to try a ladybug release, go for the preconditioned kind.

If you are shopping for ladybugs to release, make sure to look for a species that is native to your area. Vendors sometimes sell exotic ladybug species, like the Asian multicolored lady beetle. As a result of these releases, our native ladybugs are forced to compete for food and habitat.

Timing is important if you are going to try a ladybug release. If you've got too few pests for them to feed on, the ladybugs will fly off in search of a better food source. If your aphids or other pests are already abundant, the ladybugs may stay around, but it will be too late for them to make a dent in the pest population. Your goal should be to release the ladybugs when pests are at moderate levels.

If you do release ladybugs in your garden, do so in the evening. Give your garden a light misting first, so there is plenty of moisture for the ladybugs. Since the beetles are active during the day, this will encourage them to settle in for the night and you'll have a better chance of keeping them around.

You can also try making a beneficial bug food to invite the ladybugs to stay in your garden. These mixtures usually contain sugar and some other substances, like yeast, and are sprayed on your plants or applied as a paste to wooden stakes.

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