Many people wonder if certain ladybug colors indicate a “poisonous” nature. While true poisonous ladybugs are not typically encountered, some species possess defensive mechanisms that can be irritating. Most ladybugs are beneficial insects, harmless to humans, and valuable for controlling garden pests.
Understanding “Poisonous”: Defensive Secretions
Ladybugs are not truly poisonous or toxic if ingested. When threatened, many species, especially problematic ones, engage in “reflex bleeding.” This involves releasing a foul-smelling, yellowish fluid called hemolymph from their leg joints. This fluid, which is essentially the insect’s blood, is unpalatable to predators and deters them. It can also stain surfaces, such as fabrics or furniture, and may cause mild skin irritation in sensitive individuals.
Common Beneficial Ladybugs
Most native ladybug species are beneficial insects, known for their role in natural pest control. The Seven-spotted Ladybug (Coccinella septempunctata) is a common example. This species typically has a bright red or orange, round, and dome-shaped body. As its name suggests, it features seven distinct black spots on its wing covers. Both larvae and adults consume large numbers of soft-bodied pests like aphids, mealybugs, and mites in gardens and agricultural fields.
Identifying Invasive Species by Color
The Asian Lady Beetle (Harmonia axyridis) is a common invasive species that often causes concern due to its tendency to enter homes. Its coloration is highly variable, ranging from pale yellow to orange, and even deep red. These beetles may have many black spots, a few spots, or even no spots at all on their wing covers. Some forms can also be black with red or orange markings. Because of this wide variability, color alone is not a definitive way to identify an Asian Lady Beetle.
Other Key Identification Features
Since color is not a reliable identifier for the Asian Lady Beetle, other physical characteristics distinguish it from native species. A key feature is the distinctive “M” or “W” shaped black marking on the white or pale area behind its head (the pronotum). The appearance of this mark can vary, sometimes appearing as four or five distinct blotches on a lighter background. Asian Lady Beetles also tend to have a slightly more oval or elongated body shape compared to the rounder native ladybugs. Their legs are often orange-brown, unlike the black legs of many native ladybugs.
Impacts and What to Do
Asian Lady Beetles often aggregate indoors in large numbers during cooler months, seeking shelter for hibernation. While they do not carry diseases, they can be a nuisance, as they might bite, causing minor, short-lived discomfort that can be irritating. The defensive secretions released by these beetles can leave behind strong odors and yellow stains on light-colored surfaces, such as walls, curtains, or upholstery. To manage them, gently sweep or vacuum them up rather than crushing them, which prevents the release of staining fluid and odor. Sealing entry points like cracks around windows and doors can help prevent them from entering homes.