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New Mexico State University

New Mexico State University

News Center

Early Garden Insects May Damage Delicate Seedlings

LAS CRUCES -- With the onset of warm weather, New Mexico gardeners are anxious to get digging. Many already have planted crops like onions and snow peas. But their soil may contain insects that will damage the young seedlings, said a New Mexico State University entomologist.

"The first insects that we have to deal with are those that overwintered in the soil in our garden -- cutworms, grubs and wireworms," said Mike English, with NMSU's Cooperative Extension Service .

Cutworms will feed on a variety of green plants. They cut the plant off at ground level, pull it back into their hole and begin to eat. "They generally don't eat the whole plant," English said. "Instead, after a few bites, they'll just march down the row to the next plant."

White grubs, the larvae of June bugs, feed underground on the plants' roots. "Compost piles are common overwintering sites for grubs," he said. "Examine your compost carefully before applying it to young plants."

Because last year's June bug populations were high, English predicts grubs will be a common problem in the state this year.

The third early garden insect to watch for is the wireworm -- the click beetle larva. The jointed, copper-colored larva also feeds on plant roots and can cause severe damage.

Plots with sod or ground cover are more prone to soil insects and may need treatment. English recommends turning the soil over several weeks before planting. "If you notice a large number of these insects, it's probably a good idea to pretreat the soil with an insecticide."

Granular insecticides should be tilled into the garden two to three weeks before planting. After the garden is planted, larger cutworms and grubs can be seen easily. For gardeners who prefer not to use insecticides, English suggests removing pests by hand. "Keeping the soil tilled also does a lot to control soil insects," he said.