What Are the Red and Black Bugs on My House?
Updated: Nov. 15, 2022
Boxelder bugs invade homes each year, making them some of the most annoying fall pests. But they aren’t the only red and black bugs found around the home.
Each fall, boxelder bugs and Asian lady beetles search for a warm winter shelter. Unfortunately, your house may be the place they pick.
While you may find these red and black bugs throughout the year, fall is when they really become pests. Learn about these annoying fall pests as well as four other black and orange beetles that could be lurking in your yard. Once you know what you’re dealing with, keeping fall pests out becomes much easier.
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Boxelder Bugs
Many of the black and orange beetles on this list look similar. You can distinguish between them by their distinctive behaviors and markings.
If you have a large congregation of ovular, red and black bugs on the sunny side of your house each fall, your problem is probably boxelder bugs. They’re infamous for covering outer walls in search of the last rays of summer sun. Can you blame them?
You can get rid of boxelder bugs outside by applying pesticide and covering potential entryways. If they do make their way inside, know that they do not cause structural damage or breed within your home, unlike termites. Once they are inside the house, simply vacuum them up with a hose attachment. They may leave behind stains if you crush them.
Asian Lady Beetle
Asian lady beetles are often called ladybugs because the two insects look nearly identical at first glance. If you have small, round, black and orange beetles in your windowsills, the Asian lady beetle is the most likely culprit.
Like boxelder bugs, you may find these unwelcome pests in high numbers, but they don’t typically cover sides of buildings in quite the same way. Instead, they’ll weasel their way into your home to escape the oncoming winter, buzz around your light bulbs for a while, then drop dead before spring. They are a predator to the native ladybug. And although mostly harmless, sometimes they bite.
Keep lady beetles out of your house with physical and chemical deterrents.
Native Ladybug
Native ladybugs are less common than the invasive Asian lady beetle these days, but they are more desirable to gardeners. Unlike the Asian lady beetle, ladybugs do not bite or invade homes in the winter. Plus, their appetite for aphids and other plant-eating insects makes them a great natural pest control. Many garden centers even sell packages of them. The store-bought ladybugs can contain Asian lady beetles, though, so be sure to research the source before making a purchase.
To distinguish between these two red and black bugs, look at their size and markings. There are many species of true ladybugs, but they are usually smaller and rounder, with little white spots on their cheeks. Asian lady beetles have more white markings in general, including larger cheeks and an M shape where the head meets the body.
Scarlet Lily Leaf Beetle
Another red and black bug that could wreak havoc in your garden is the scarlet lily leaf beetle. These are particularly annoying for those who are fond of lilies. These beetles are red on top and black on the bottom.
According to Gardener’s Supply Company, the adult beetles munch on lily leaves and lay eggs on their undersides. Their larvae can decimate leaves, buds, and flowers.
Scarlet lily leaf beetles overwinter in the ground, so you don’t have to worry about them invading your home in the fall. These pests are worst in the spring — around the time daffodils and lilies bloom.
Firebug
If you haven’t heard of the firebug, it’s probably because they aren’t common in North America. According to the Natural History Museum of Utah, outside of Europe, these black and red bugs are only found in Utah. Don’t confuse these with fireflies as they’re not the same thing!
Actually, European firebugs look and behave much like boxelder bugs. They have an ovular body, long legs, and black and red markings on their backs. They may gather in large numbers on buildings and other structures. They can even leave behind stains when crushed. The main difference is that they cannot fly.
If you live in Utah and are encountering firebugs, preventative measures are the same as with boxelder bugs. Be sure to report your sightings to the Firebugs of Utah project so that their spread can be documented.
Milkweed Bugs
Common milkweed is one of the best flowers for bees, butterflies and other pollinators. It blooms with round clumps of small, mauve, good-smelling flowers. Most people plant milkweed to attract monarch butterflies. However, it can attract nuisance bugs as well.
If you have this plant in your yard, keep an eye out for the boxelder bug-like group of black and orange beetles known as milkweed bugs. The Save Our Monarchs Foundation gives an overview of four milkweed bugs. Only one species, the small milkweed bug (pictured), is harmful to monarchs.
Look for an X or hourglass shape on its back to distinguish the small milkweed bug from other red and black bugs.
