Ladybugs belong to the beetle family Coccinellidae and are recognized as beneficial insects in gardens and agricultural settings. A common concern is whether these small, brightly colored beetles consume wood or cause structural damage to homes. Ladybugs do not eat wood, nor do they pose a threat to the structural integrity of houses. Their feeding habits contrast sharply with the destructive nature of true wood-boring pests.
What Ladybugs Actually Eat
The typical diet of a ladybug consists almost entirely of soft-bodied agricultural pests, making them natural predators. Their primary food source is aphids, tiny sap-sucking insects that damage plants by extracting nutrients and spreading viruses. A single adult ladybug is a voracious consumer, capable of eating up to 5,000 aphids during its lifetime, demonstrating their substantial value in pest control.
Beyond aphids, their diet also includes scale insects, mealybugs, mites, and the eggs of other insects. The ladybug larvae are equally predatory and can consume hundreds of pests before pupating. This predatory behavior is why ladybugs are actively introduced as a form of biological control in both home gardens and large-scale farming operations.
Why Ladybugs Are Found Near Wood Structures
The presence of ladybugs around and inside wood structures is a direct result of their overwintering behavior, not a search for food. As temperatures drop in the fall, adult ladybugs enter a period of dormancy known as diapause to survive the winter. They seek out protected, sheltered locations to aggregate in large numbers for insulation and safety.
These shelter sites often include cracks in rocks, under tree bark, in hollow logs, or within the structural voids of buildings. The beetles communicate the location of a suitable shelter by releasing aggregation pheromones, which attracts hundreds of other ladybugs to the same spot. When they enter homes, they do so accidentally through small openings in siding, windows, or foundations, seeking warmth and protection until spring.
Distinguishing Ladybugs from Wood-Boring Pests
If wood damage is present, the culprit is not a ladybug, as these beetles lack the mouthparts necessary to consume wood. True wood-boring pests, such as termites, powderpost beetles, or carpenter ants, actively tunnel into wood for food or to create nesting galleries. Ladybugs, by contrast, are simply sheltering and will not chew through wood to gain entry or establish a colony.
The specific species often found indoors is the multicolored Asian lady beetle (Harmonia axyridis). This species can be differentiated from native ladybugs by a few visual markers. The Asian lady beetle is slightly larger and frequently has a distinct black “M” or “W” shape on the white area behind its head, a marking absent on most native species. When disturbed, the Asian lady beetle may excrete a yellowish fluid that can stain surfaces; this is a defensive mechanism against predators.