Insects displaying striking red and black patterns often capture attention. These vivid color combinations can serve as a natural warning to predators, signaling that the insect might be unpalatable or toxic. Understanding these common red and black insects helps appreciate their roles in various environments. This article identifies several common species and explains their typical interactions with humans and the ecosystem.
Identifying Common Red and Black Insects
One of the most recognized red and black insects is the ladybug. These small beetles typically have a round or oval, dome-shaped body, measuring about 0.3 to 0.4 inches in length. While often bright red with black spots, their coloration can vary, including orange or even black with red markings. Ladybugs are commonly found in gardens, shrubs, and trees, often congregating in protected areas for overwintering.
Boxelder bugs (Boisea trivittata) are slender, flat-bodied insects, approximately 0.5 inches long. They are predominantly black with distinct reddish-orange markings, including lines along the edges of their wings and a central stripe on their thorax. When at rest, their wings often overlap, forming an ‘X’ shape on their backs. Younger boxelder bugs, known as nymphs, appear mostly red and lack fully developed wings. These insects are frequently observed on boxelder, maple, and ash trees, and they tend to gather on the sunny, south-facing sides of buildings.
Milkweed bugs are primarily associated with milkweed plants. The large milkweed bug (Oncopeltus fasciatus) measures about 0.75 inches long, with an orange-red body and a prominent black band across its back. Its wings also feature black markings, sometimes forming an X-shaped pattern.
A related species, the small milkweed bug (Lygaeus kalmii), is similar in appearance but generally smaller, up to 0.5 inches. It can be distinguished by a reddish-orange X-shape on its back and a red band on its pronotum. Both large and small milkweed bugs are typically found on milkweed plants, where they feed on seeds, leaves, and stems.
The California bordered plant bug (Largus californicus) is a true bug found in western North America. Adults have a black body with striking orange or red edges along the thorax and abdomen, reaching about 0.5 to 1 inch in length. Nymphs are metallic blue with a red spot that develops at the base of the abdomen. These insects inhabit grasslands and forests, and are often seen in residential areas, particularly on patios.
Understanding Their Impact
Ladybugs are widely regarded as beneficial insects, especially in gardens and agricultural settings. Both adult ladybugs and their larvae are predators that consume soft-bodied pests, such as aphids, mites, and mealybugs, which can damage plants. A single ladybug can consume thousands of aphids over its lifetime, making them natural pest control agents. Some species, particularly the Asian lady beetle, may enter homes in large numbers during cooler months in search of overwintering sites, becoming a nuisance. When disturbed or crushed, they can release a foul-smelling fluid and may stain surfaces.
Boxelder bugs are primarily considered nuisance pests. They do not typically bite humans or transmit diseases. Their feeding on the sap of boxelder, maple, ash, and fruit trees can occasionally cause minor deformities in leaves or fruit, but usually does not significantly harm the trees. The main concern arises when they congregate in large numbers on homes, seeking warmth in the fall. Inside structures, their excrement can stain curtains, furniture, and walls, and crushing them releases an unpleasant odor.
Milkweed bugs, both large and small, feed on the seeds and sap of milkweed plants. While they can be abundant on milkweed, they generally cause little significant damage to the plants themselves, acting more as a nuisance. They can, however, interfere with seed production if the goal is to harvest viable milkweed seeds. These insects are not known to bite humans or pets.
California bordered plant bugs primarily feed on plant sap, often from flowers and fruits. They typically do not cause significant damage to ornamental plants. These bugs are generally considered non-toxic and do not pose a health risk to humans.
Managing Their Presence
For beneficial insects like ladybugs, the most appropriate approach is typically to leave them undisturbed. If ladybugs enter a home, they can be gently swept or vacuumed and released outdoors. Allowing them to remain in the garden supports natural pest control efforts.
Managing nuisance insects like boxelder bugs often focuses on preventing their entry into homes. Sealing cracks and openings around windows, doors, and foundations with caulk or weatherstripping can help deter them. Vacuuming is an effective method for removing bugs that have already entered a home. Removing female boxelder, maple, or ash trees from the immediate vicinity of a home, or clearing fallen seeds, may reduce their populations, though bugs can fly in from neighboring properties.
Milkweed bugs generally do not require intervention due to their minimal impact on milkweed plants. If their presence is undesirable, such as when seed production is a priority, handpicking them off plants and dropping them into soapy water is an effective method. Removing leaf litter and spent plant stalks in the fall can also help reduce overwintering sites.
For California bordered plant bugs, management is rarely necessary as they cause little plant damage. If their populations become very high, general eco-friendly pest control strategies can be considered. These include encouraging natural predators, using physical barriers like fine mesh netting, or applying natural repellents such as neem oil or insecticidal soaps.