Hungry Insects, Leave my tomatoes alone!

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Master Gardeners go beyond the confines of the garden to answer and research gardening questions of all kinds throughout the entire growing season. We tend to notice trends. Those trends allow me to provide continued training for the Master Gardeners so that they can better serve the public.

The trends also give me insight into what people want to know. In the past few weeks, for instance, we have had numerous questions about blister beetles, green fruit beetles, lace bugs and tomato fruit worm.

Blister beetles are elongated, oval-shaped beetles with soft wings. Most of the ones I have seen have been Margined blister beetles, with black wings and ash gray bodies. They are called blister beetles because they spray a defensive oil that can cause blisters. Photo by Kelly Allsup.

Most found in the garden contain low amounts of this chemical and cannot harm the gardener. They feed on a wide range of garden plants, like tomatoes and potatoes, and can feed in large colonies, decimating plants before they move on. The larvae stage are considered beneficial insects because they eat grasshopper eggs in the soil.

They stop feeding in the middle of the summer, so some gardeners either knock them into a container of soapy water, use an organic product like neem oil or Spinosad, or ignore them.

Green fruit beetles, brilliantly green and rather large, fly around like little buzzing helicopters in July and August, feeding on thin-skinned fruits like raspberries and blackberries. They are not as much of a nuisance as their larvae, which feed on turf roots. The larvae burrow up to the surface to feed, making holes in the lawn. Photo by University of Kentucky.

Lace bugs look like tiny squares of lace feeding on the back of your leaves. The feeding injury is caused from the piercing and sucking mouth parts. Their excrement is strategically placed along the vein and secures the eggs to the leaf. Nymphs are small, shiny brown, and congregate while they are young. Damage from high populations is more severe in dry weather. I have seen lace bugs on sunflowers, oak leaves and sycamore. Hover fly larvae, lady beetles and lace wing larvae will prey on these garden pests. Daily water sprays until population is reduced can be highly effective. Photos by University of Illinois.

Tomato fruit worm can be a big disappointment to gardeners who have tended their tomato plants all season long. The bugs are also known as corn earworm. The larvae bore into the tomato and eat it from the inside out. The night-flying moths lay their eggs on the plants close to first flower. Once in the fruit, they exit through a quarter-of-an-inch hole. Fruit worms do not devastate the tomato crop; damaged fruit can be tossed without using insecticides. Photo by University of Kentucky.