10 Red and Black Bugs You Can Find in Your Garden

Learn to Tell These Red and Black Bugs Apart

When you're a small bug in a big world, you'll use every trick in the book to avoid being eaten. Many insects use bright colors to warn predators to avoid them. If you spend even a short time observing the insects in your backyard, you'll quickly notice there is an abundance of red and black bugs out there.

While lady beetles are probably the best known red and black bugs, there are hundreds of red and black true bugs (Hemiptera), and many share similar markings that make them tough to identify. The 10 red and black bugs in this list represent some of the true bugs that gardeners and naturalists might encounter and wish to identify. Some are beneficial predators, like assassin bugs, while others are plant pests that might warrant control measures.

01
of 10

Cotton Stainer Bug

Cotton stainer bug.
The cotton stainer bug. Flickr user Katja Schulz (CC license)

 The cotton stainer, Dysdercus suturellus, is a pretty bug that does ugly damage to certain plants, including cotton. Both adults and nymphs feed on the seeds in cotton bolls, and stain the cotton an undesirable brownish-yellow in the process. Before the advent of chemical controls for this crop pest, the cotton stainer caused serious economic damage to the industry.

Unfortunately, the cotton stainer doesn't limit its attention to cotton plants. This red bug (that's the actual name for the family, Pyrrhocoridae) damages everything from oranges to hibiscus. Its U.S. range is limited to mainly to southern Florida.

02
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Two-Spotted Stink Bug

Two-spotted stink bug.
A two-spotted stink bug. Louis Tedders, USDA Agricultural Research Service, Bugwood.org

 Stink bugs are also true bugs, and can usually be recognized by their characteristic shape. Like all true bugs, stink bugs have mouthparts designed for piercing and sucking their food. What they eat, however, varies a great deal. Some stink bugs are plant pests, while others are predators of other insects and therefore considered beneficial.

One of the more striking species of stink bugs, the two-spotted stink bug (Perillus bioculatus) is identified by its bold and distinctive markings. The two-spotted stink bug isn't always red and black, but even in its less brilliant color forms, it can be identified by the presence of two spots just behind the head. The species is also called the common name double-eyed soldier bug, and the scientific name bioculatus actually means two eyes.  

Two-spotted stink bugs are among the beneficial predators in the family Pentatomidae. Although a generalist feeder, the two-spotted stink bug has a known preference for eating Colorado potato beetles.

03
of 10

Scarlet Plant Bug

Scarlet plant bug.
A scarlet plant bug. Getty Images/PhotoLibrary/Dr Larry Jernigan

Scarlet plant bugs (genus Lopidea) belong to the plant bug family, and are among the insects that feed on and damage their host plants. Individual species are often named for their host plants, like the scarlet laurel bug, which feeds on mountain laurels.

Not all Lopidea are red and black, but many are. They're typically brilliant scarlet around the outer margins, and black in the center. Scarlet plant bugs are quite small at 5-7 mm in length, but attention grabbing thanks to their bright colors. Almost 90 species belong to this group, with about 47 scarlet plant bugs in the U.S. and Canada.

 

04
of 10

Fire Bug

Fire bug.
A fire bug. Getty Images/Oxford Scientific/Ian West

​While the firebug (Pyrrhocoris apterus) is not native to the Americas, it is occasionally found in the U.S. and a population of firebugs is established in Utah. Its striking markings and colors will definitely attract your attention, should you find one. During their mating season, they're often seen in mating aggregations, making them easier to spot.

The firebug is one of the smaller red and black bugs, measuring perhaps 10 mm in length as an adult. Its identifying marks include a black triangle and two distinct black spots on a red background. The firebug is typically found around lindens and mallows in the places where it resides in the U.S.

 

05
of 10

Milkweed Assassin Bug

Milkweed assassin bug.
The milkweed assassin bug. Ann Schulz, Insects Unlocked Project (public domain)

The milkweed assassin bug (Zelus longipes) doesn't prey on milkweed plants, of course. It is a true assassin bug that hunts all manner of soft-bodied insects, from caterpillars to beetles. Its common name comes from its resemblance to the large milkweed bug, Oncopeltus fasciatus. These very different true bugs share similar markings, making it easy for the amateur observer to misidentify them.

This beneficial predator is also known as the long-legged assassin bug (longipes actually means long-legged). Its body, from head to abdomen, is mainly red or orange in color, with distinctive black markings on the thorax and wings. They usually overwinter as adults.

 

06
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Bee Assassin Bug

Bee assassin bug.
The bee assassin bug. Flickr user Joe Flannery (CC by SA license)

The bee assassin bug, Apiomerus crassipes, is not just a threat to bees. This generalist predator will readily consume any arthropod it encounters, including honey bees and other pollinators. Like other cunning assassin bugs, the bee assassin lies in wait for prey, resting on flowering plants until a suitable meal lands within reach. Bee assassins have sticky hairs on the first pair of legs that enables them to grip their prey. While most assassin bugs are poor fliers, the bee assassin is a notable exception.

Bee assassin bugs are mostly black, with red (or sometimes yellow) markings along the sides of the abdomen. Within the species, individual bee assassins can vary quite a bit in size, with some as small as 12 mm and others as long as 20 mm. Although generally docile, a bee assassin bug will bite in self-defense if handled carelessly

07
of 10

Bee Assassin Bug

Bee assassin bug.
The bee assassin bug. Alejandro Santillana, Insects Unlocked Project (public domain)

​Another bee assassin bug, Apiomerus spissipes, illustrates the similarities between members of this genus. Like its close cousin, Apiomerus crassipes, this bee assassin doesn't limit its meals to bees alone. It is a generalist predator that will readily ambush any arthropod that crosses its path when it is hungry.

This species is even more stunning than A. crassipes, thanks to the bright yellow markings that accent its red and black coloration. The bee assassin bug was even honored with a U.S. postage stamp in 1999.

08
of 10

Large Milkweed Bug

Large milkweed bug.
The large milkweed bug. Flickr user David Hill (CC license)

Anyone who grows milkweed for monarchs will be familiar with this common red and black bug, the large milkweed bug (Oncopeltus fasciatus). Those who aren't in the know may mistake them for boxelder bugs. 

Large milkweed bugs feed on the seeds of milkweed plants, and occasionally on the nectar. As the milkweed seed pods mature, they'll often attract dozens of large milkweed bugs, both nymphs and adults. Bugguide notes that they overwinter as adults, and large milkweed bugs from colder climates will migrate south for the winter. 

Large milkweed bugs aren't actually all that large at 10-18 mm long. They can be identified by their markings: black diamonds on a reddish orange background at front and back, and a solid black band across the middle.

09
of 10

Small Milkweed Bug

Small milkweed bug.
The small milkweed bug. Flickr user Denise Krebs (CC license)

The small milkweed bug (Lygaeus kalmii) also hangs around the milkweed patch, feeding on seeds when they are available. Its feeding habits aren't entirely clear, however. Some observers report small milkweed bugs feeding on flower nectar, scavenging on dead insects, or even preying on other arthropods.

Small milkweed bugs reach only 12 mm or so in length at their largest. They are easily identified by the presence of a reddish orange "X" on the back, although the lines forming the "X" don't completely meet in the center.

 

10
of 10

Eastern Boxelder Bug

Eastern boxelder bug.
The eastern boxelder bug. Flickr user Katja Schulz (CC license)

If you live east of the Rocky Mountains, you may discover eastern boxelder bugs when they gather in large numbers on the sunny side of your home. Boxelder bugs (Boisea trivittatus) have an unfortunate habit of invading homes in the fall, and for this reason, people often consider them pests. A similar species, the western boxelder bug (Boisea rubrolineata) inhabits the western U.S. states.

Both adult and larval boxelder bugs feed on sap taken from the seeds, flowers, and leaves of their host trees. They mainly feed on maples, including the boxelder maples from which they get their name. However, their diet isn't limited to Acer spp., and oaks and ailanthus are also likely to attract them.

The eastern boxelder bug measures a half inch long at most, and is clearly outlined in red along the outer edges. A red stripe down the center of the pronotum is also a key identifying mark.

 

Sources:

  • "Twospotted Stink Bug," Biological Control Information Center, Department of Entomology, North Carolina State University website. Accessed online May 9, 2017.
  • Cotton Stainer, Featured Creature, Department of Entomology and Nematology, University of Florida website. Accessed online May 9, 2017.
  • "Boxelder Bugs," Jeff Hahn and Mark Ascerno, University of Minnesota website. Accessed online May 9, 2017.
  • "Bee Killer Assassin Bug," by Candice Hawkinson, Galveston County Master Gardeners, Texas A&M University website. Accessed online May 9, 2017.
  • Milkweed Assassin Bug, Featured Creature, Department of Entomology and Nematology, University of Florida website. Accessed online May 9, 2017.
  • Pyrrhocoris apterus, Firebug, British Bugs website. Accessed online May 14, 2017.
  • Bugguide.net. Accessed online May 14, 2017.