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The bold red color and black markings on red firebugs make them hard to overlook.

Courtesy Meredith Seaver, USU Extension

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Red firebugs can often be seen in groups.

Courtesy Meredith Seaver, USU Extension

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Firebug nymphs are red but lack the distinctive black markings you'll see on adult red firebugs. Instead, you'll see a line of 3 small black dots on their backs.

Courtesy Meredith Seaver, USU Extension

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Last year my flower and shrub beds were eaten by bugs that I never could catch in the act. This year the bugs are back and it’s easy to see them crawling around on the mulch and on some of the plants. They are black and red and I’m pretty sure they are firebugs. Now I wonder if they are responsible for all the eaten plants in that area, including weeds, bushes, trees?

There are two black and red bugs that we may often see in our landscapes. One is the boxelder bug, which is very common in landscapes with female maple trees. The other bug is the red firebug, a relatively new pest that was first seen in local landscapes in 2008. Adult red firebugs are easily identified by their bold and distinctive black and red markings. These bugs aren’t native to Utah, but they’re now well established in our area. Fortunately for local gardeners, the red firebug is harmless to people, pets and plants.

Red firebugs have piercing, sucking mouth parts, not chewing mouthparts. They feed on seeds, not foliage, so they aren’t responsible for the plants in your landscape that have chewing damage. This has been a big year for grasshoppers, and they may be to blame for the damage you’re seeing on your plants.

Because red firebugs are harmless and don’t cause plant damage, they’re considered nuisance pests and chemical controls aren’t recommended. They’re a nuisance nonetheless, and there are several things you can do to reduce their presence in your landscape or home.

Red firebugs tend to avoid direct sunlight by seeking shelter in foliage, under plant debris and in garden sheds or shady areas near homes, etc. They will also enter homes late in the season to find overwintering shelter. Avoid crushing red firebugs if you need to remove any from your home. They produce offensive odors and can also cause stains on carpets and other textiles, making them particularly unwelcome.

Good exclusion practices are the solution to this pest problem and other pests that may want to come indoors at certain times of the year. Elm seed bugs, boxelder bugs and spiders are just a few that come to mind. Seal up any openings that may provide an entrance to your home if you’ve been finding this nuisance pest indoors.

• Window frames should fit into walls tightly and windows should fit into the frame tightly. Expanding foam caulk can seal any small gaps.
• Screens should be in good condition and fit tightly as well.
• White duct tape can be used to seal off the tiny gap between screens and window frames.
• Weather stripping, door sweeps and good thresholds are also helpful.
• Expanding foam caulk can also seal up gaps where gas or electrical conduits enter the home. Check for any other voids in the exterior of your home.

Keep flower and shrub beds clean, especially near the foundation of your home. Plant debris provides attractive shelter for red firebugs and other nuisance pests. A monthly cleanup can keep the “pest shelter” to a minimum.

Promptly deadhead flowers when they fade. This will prevent seed set, which attracts hungry red firebugs. This is very important if you include malva, hibiscus, mallow, linden and hollyhocks in your landscape as these are favorites of the red firebug.

Good weed control will also help to keep red firebug populations low. There are many plants in addition to their favorites that serve as food sources for the bugs and some of them are considered weeds.

The young nymphs of red firebugs are fragile and easily injured or drowned. You can use strong sprays of water to hose down any bugs that you find congregating on exterior walls, tree trunks or mulch areas. Including insecticidal soap in the water will increase the effectiveness of this technique.

By employing a combination of the strategies I’ve mentioned throughout each season, you should see an improvement in your red firebug problems.

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