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Garden Help Desk: Red fire bugs are harmless pests

By Meredith Seaver usu Extension - | Apr 3, 2021
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Red fire bugs are non-native insects that are relatively new to Utah. They feed on mature, dry seeds and are not harmful to people, pets or landscape plants. They become a nuisance when they come indoors during the summer to escape the heat.

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Organic matter in the soil, such as bits of wood or dead vegetation that hasn't broken down yet, can be a food source for beneficial fungi and bacteria.

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Small pieces of wood on the surface of the soil spent the winter and early spring covered by a dense mat of leaves -- the perfect habitat for beneficial fungi that break down wood.

Question: I am wondering what type of bug this is in my photo and how to manage it so that they don’t ruin my plants? There are quite a few of them in my yard. Any help would be appreciated!

Answer: These are red fire bugs, a relatively new insect in our area that may have arrived in imported plant material. I noticed a few of them in my own yard last year. They are native to central Europe and were first found in Salt Lake County in 2008. For the past few years, red fire bugs have become more common in parts of Utah County. These insects are harmless to you and your pets and don’t bite or sting, but they can cause stains on carpets and upholstery if they manage to get inside your home.

Red fire bugs are members of the same large order of insects that includes other true bugs such as boxelder bugs, squash bugs and elm seed bugs. Just like elm seed bugs and boxelder bugs, red fire bugs congregate in groups and can be found on exterior walls, on plants, in mulch or under leaf litter. They seek out shade during the day and may enter buildings during the summer to escape the heat.

These bugs are seed feeders and have a wide host range in their native habitat. We don’t know much yet about their preferred hosts in Utah, but since they use their straw-like mouthparts to feed on mature, dry seeds, it’s unlikely you’ll see much plant damage in your own landscape.

Red fire bugs are nuisance pests because of the habit of congregating on buildings and plants and because they find ways to get into homes and other buildings. Since they don’t cause damage to our landscape plants and the adults can tolerate many insecticides, chemical controls aren’t the first option you should consider when you’re having problems with this pest. There are non-chemical methods that can be helpful.

Here are some things to try first:

— Tolerate the presence of red fire bugs if they aren’t actually causing problems.

— Insects in the true bug order can be easily drowned, especially the younger ones. Directly spraying groups of red fire bugs every day or two with a stiff spray of water can reduce problems with this pest.

— Soapy water sprays are another option you can try. One gallon of water combined with one-half cup of dishwashing liquid can be sprayed directly on the bugs. The soapy water won’t have any residual effect after it dries, but it will kill the bugs you’ve sprayed.

— You can reduce the number of red fire bugs that get into your house by sealing openings such as gaps between window frames and walls, openings where gas, electrical and plumbing service enters your home and other cracks and gaps with caulk. Weather stripping and door sweeps plus good thresholds also will help.

— Any red fire bugs that do manage to get into your home can be vacuumed up and disposed of.

Question: We have a white powdery mold on our garden dirt after I raked up the pile of leaves. Is that something I need to remove before we plant our vegetables or is it fine?

Answer: Not all of the fungi and bacteria in soils and composts are harmful. There also are many beneficial organisms that play an important role in breaking down organic matter. Your photo looks like you had some of these good guys hard at work decomposing organic materials in your garden. One of these microorganisms, called white mold, grows on wood, when it is in the soil or under dense or matted layers of leaves or other debris where oxygen is less available. If you take a closer look at your photo, you’ll see that the white material is on small bits of wood that haven’t quite broken down yet, not growing on the soil itself. This same fungus has been active in my own garden and I’ve included a photo of fungi I found when I was turning the soil.

Your soil is safe to use; there’s no need to remove it or the wood bits before you prepare and plant your garden.


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