Invasive Insects Calling Caldwell County Home

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There are a bunch of invasive insects that now call Caldwell County home. Most of these insects do not directly affect homeowners. However, indirectly these new invasive insects affect all of us. These news pests range from tracheal mites and small hive beetles which bother honey bees to the kudzu bug and the brown marmorated stink bug which like to snuggle up with us in our homes during the winter.

The list of recent invasive insects is actually very long. Many homeowners are familiar with hemlock wooly adelgid, ambrosia beetle, and the emerald ash borer. However, one of the newer insects causing problems is spotted the wing drosophila (SWD). The SWD is a new invasive fruit fly that is causing problems for farmers and home gardeners.

Native fruit flies infest overripe fruit. This is fruit that is well past its prime, stuff we would not eat. However, the SWD lays its eggs in unripe fruit. This a concern for farmers and gardeners. Customers do not like to consume fruit that has fruit fly larva inside and there is zero tolerance in the industry for this pest. Crops most at risk from SWD are strawberries, figs, raspberries, blackberries, cherries, grapes, and blueberries. In addition SWD can also reproduce in peaches, plums, pawpaw, mayapple, honeysuckle, elderberry, persimmon, autumn olive, pokeweed, and japanese yew.

South Carolina strawberry growers had early season SWD infestation. This early season infestation is being attributed to the mild winter. In North Carolina, there is an active monitoring program to detect SWD.

I expect this summer we will see problems in home gardens. Gardeners will notice fruit spoils quicker than usual.

Two spotted wing drosophila larvae in a fresh strawberry. (Dr. Hannah Burrack)

Two spotted wing drosophila larvae in a fresh strawberry. (Dr. Hannah Burrack)

There will also be tiny white larvae in the fruit. These little larvae are only slightly larger than a strawberry seed.

There are monitoring traps for SWD, but the best course of action for the home garden is sanitation. Sanitation reduces SWD populations.

Traps for SWD insects

This is an NC State Extension experiment to determine which traps are best for monitoring spotted wing drosophila. Yeast and sugar as baited traps performed the best in North Carolina trials. (Dr. Hannah Burrack)

Basically, harvest ripe fruit every day and don’t leave overripe fruit in the garden/orchard. Pick and destroy old fruit and all that has fallen to the ground.

The fallen fruit and infested fruit should be placed it in a plastic bag and seal it tightly. Put the old/fallen fruit into a clear plastic ziplock bag put in the sun or in the freezer to kill any SWD larvae. Plastic bags can also be placed in the trash. I don’t recommend composting this old/fallen fruit because it may not kill the SWD.

If your fruit looks fine but you still suspect an infestation, place it in the refrigerator. Chilling will slow or stop the development of larvae and the fruit can be eaten.

Although sanitation is the first step for SWD infestations, fruit can also be protected by with common garden insecticides. One of the safest insecticides on the market that is effective against SWD is spinosad. This product is sold under such brand names as Captain Jack’s Deadbug Concentrate and Conserve Naturalyte.

For additional information on SWD visit our webportal on this topic at and for answers to your other agricultural questions, call the Caldwell County Extension Center at 828-757-1290, or visit us online anytime at