Ladybugs, a diverse group of insects in the Coccinellidae family, are commonly known for their distinctive red and black spotted appearance. However, these beetles exhibit a wide spectrum of colors and patterns, including yellows, oranges, black, and even metallic blue. This varied coloration often leads to questions, especially when encountering a ladybug that deviates from the familiar red, such as a brown one.
Identifying Brown Ladybug Species
The term “brown ladybug” frequently refers to specific species that naturally display brown or tan variations. The multicolored Asian lady beetle (Harmonia axyridis) is one of the most commonly encountered, exhibiting a wide range of color forms, including tan, orange, and red, with varying numbers of black spots or no spots at all. These beetles are typically oval and convex, measuring approximately 0.2 to 0.3 inches (5.5 to 8.5 mm) in length.
Beyond the Asian lady beetle, several native brown ladybug species exist. The Larch Ladybug (Aphidecta obliterata) is often tan to brown with a distinct M-mark on its pronotum and a black head, frequently found on coniferous trees. The Cream-Spot Ladybug is a reddish-brown beetle with 14 white spots on its wing cases and a white spot on either side of its thorax. The Striped Ladybug (Myzia oblongoguttata) is chestnut-colored with creamy-white spots and stripes, while the Heather Ladybug (Chilocorus bipustulatus) is dark brown with two reddish-orange spots. These native species typically range from 0.12 to 0.20 inches (3 to 5 mm) in length.
Distinguishing Features and Behaviors
Distinguishing brown ladybugs from other insects or more typical red ladybugs involves observing specific features and behaviors. The multicolored Asian lady beetle often has a prominent “M” or “W”-shaped black marking on the whitish area behind its head, which is a key identification characteristic. Their physical size is generally larger than many native ladybug species. These beetles are known for their tendency to aggregate, especially as autumn approaches, seeking sheltered locations to overwinter.
Unlike many native ladybugs that overwinter outdoors in sheltered sites, multicolored Asian lady beetles frequently seek hibernation sites inside and around buildings. When disturbed, these beetles can secrete a foul-smelling, yellowish fluid from their leg joints, a defense mechanism known as reflex bleeding. This fluid can stain light-colored surfaces. While ladybugs generally do not bite humans, multicolored Asian lady beetles are known to occasionally bite, feeling like a pinprick, particularly when searching for moisture or food.
Ecological Role and Human Interaction
Brown ladybugs, particularly the multicolored Asian lady beetle, play a dual role in ecosystems and human interaction. As predators, they are beneficial in controlling agricultural pests, primarily consuming aphids and scale insects. An adult beetle can consume hundreds of aphids per day, making them effective biological control agents. This predatory behavior extends to other soft-bodied insects, contributing to plant health in gardens and agricultural settings.
Despite their benefits, the multicolored Asian lady beetle is considered an invasive species in many regions outside its native Asia. Their voracious appetite and high reproductive rate allow them to outcompete native ladybug species for food resources and even prey on native ladybug eggs and larvae. This competition can lead to declines in native ladybug populations.
These beetles often become a nuisance in the fall when they seek warmth and shelter, invading homes and buildings in large numbers. Their tendency to secrete fluid can cause staining on indoor surfaces, and large infestations can sometimes trigger allergic reactions in sensitive individuals. In vineyards, inadvertently processed beetles can also taint the flavor of wine due to their defensive secretions.