Some, like earthworms, are helpful because they aerate the soil and convert unusable materials into something plants can utilize. Others, including many types of moth larvae, feed on vegetable plants and are detrimental to gardens. Jarratt said earthworms and insects that may look like worms are two totally different types of creatures. The larvae of moths often look like worms because they are elongated and crawl like worms, but they are actually insects. Insect larvae usually pose the greatest threat to garden yields.
Gardeners have several insects that can damage their vegetables.
The average tomato grower in Mississippi is more likely to see damage from the tomato horn worm, which only feeds on tomatoes, than the tomato fruit worm, which also likes corn. The cabbage looper feeds on many types of greens, including cabbage, lettuce, turnip greens and broccoli. Jarratt said this insect becomes less of a problem as the weather heats up because the green vegetables go out of season. In addition to the many larvae insects that damage gardens, beetles also pose a threat. There are a number of beetles that feed on the foliage of peas and beans.