"Ladybugs are probably the premier predators in the garden," the Brigham Young University entomologist said.

In one day, the polka-dotted fliers can eat several times their own body weight in aphids, common garden pests.

One particular breed of ladybug, a group imported from Asia, has caught Booth's attention. When compared with American ladybugs, Asian counterparts can keep eating at lower temperatures.

In theory, this is a good thing. If you have Asian ladybugs on your plants, they will eat predators longer than native ladybugs, meaning more predators are removed, Booth said.

But there are questions about how well Asian and American ladybugs get along.

"The Asian species is coming, and appears to be displacing the native species," he said.

Booth recently published a study comparing the ladybug breeds in the journal Environmental Entomology. Part of the research dealt with whether the Asian ladybugs' competitive advantage is a threat to home-grown breeds.

Booth put ladybugs from the United States and Asia in special chambers to measure their body heat, respiration and how much carbon dioxide they exhale.

Although they look the same, the Asian version seems to keep chowing down in the lower temperatures that prompt American ladybugs to take a siesta.

It remains unclear what this means for native species. Perhaps the two breeds could work well together, but there is also a chance the Asian strain could take over.

Booth said the Asian ladybugs are now found across the United States, with some collected in Logan.

The Utah Department of Agriculture and Food advises against importing any ladybugs that are not native to the United States, said Larry Lewis, department spokesman.

When Willard Bay Gardens launches its annual assault on aphids, it relies on native ladybugs, said Della Barnett, co-owner of the plant nursery.

Employees unleash thousands of ladybugs in greenhouses and on nearby fields each spring.

"Larvae are what you're really after," Barnett said. "They're the cleanup crew."

Ladybugs released in the spring will mate and lay eggs. When the larvae hatch, they start feasting on any unwanted creatures hanging out on your plants.

"They're known for aphids, but they also eat other small insects," she said. Their menu also includes thrips, whiteflies and grubs.

Releasing ladybugs now might still do some good for Utah gardens, but they are more effective when set out in early- to mid-April, Barnett said.

glavine@sltrib.com

Tips for courting a ladybug

* Ladybugs are attracted to pollen and nectar from sunflowers, cosmos, dill, anise, fennel, alyssum, daisies and coreopsis.

* Gardeners can create their own "Eau de Ladybug" solution to help lure ladybugs:

1. Mix 5 ounces of sugar in 1 quart of water.

2. Shake well.

3. Pour into spray bottle.

4. Apply to plants with aphids or scales.

Source: Trowel & Error: Over 700 Shortcuts, Tips and Remedies for the Gardener, by Sharon Lovejoy