Ladybugs, those small, often red and black-spotted insects, undergo a period of winter dormancy. This state, common among many insect species, is a temporary cessation of growth and development. It allows them to survive harsh environmental conditions and persist through colder months when food sources are scarce and temperatures are low.
The Winter Sleep (Diapause)
The winter dormancy in ladybugs is scientifically termed “diapause,” which differs from true hibernation. Diapause is a genetically programmed state of suspended development and reduced metabolic activity, triggered by environmental cues such as decreasing day length and falling temperatures. During this period, a ladybug’s heart rate and metabolism slow considerably. Energy reserves are accumulated and conserved. This reduced activity allows ladybugs to endure prolonged periods without food or water, and to build tolerance to extreme cold.
Finding Winter Shelter
As cooler temperatures arrive, ladybugs seek sheltered locations for their diapause. They often aggregate in large groups, a behavior known as aggregation. Clustering helps them conserve body heat, reduce moisture loss, and provides protection from predators during their vulnerable dormant state. Natural outdoor overwintering sites include under leaf litter, within rock crevices, beneath loose tree bark, inside hollow logs, and under snow drifts. This communal gathering is often facilitated by pheromones, chemical signals that attract other ladybugs to the same suitable location.
Ladybugs Indoors: Uninvited Guests
During autumn, ladybugs frequently enter human dwellings, seeking warmth and protection for their winter diapause. They are attracted to structures that mimic natural shelters, particularly those with light-colored, sunny, and southwest-facing surfaces. These insects can squeeze through small cracks around windows, doors, utility lines, and under siding.
Often, the species found in large aggregations indoors is the Asian Lady Beetle (Harmonia axyridis), an invasive species introduced to control agricultural pests. Native ladybugs typically prefer to overwinter outdoors.
Asian Lady Beetles can be distinguished from native ladybugs by certain characteristics. Asian Lady Beetles often have a prominent black “M” or “W” shaped marking on the white area behind their head. Their color can vary from tan to orange to red, and their body shape is more oval. Native ladybugs are generally rounder and typically a true red color, often with seven black spots. Asian Lady Beetles can also release a foul-smelling, yellowish fluid when disturbed, which can stain surfaces, and they may bite.
If ladybugs are found indoors, humane removal methods are preferred. They can be gently swept into a dustpan or vacuumed using a hose attachment with a sock placed over the nozzle, allowing for their release outside. Sealing entry points like cracks around windows and doors before colder weather arrives can prevent them from entering. Natural repellents such as mint, citrus oil, cloves, or planting mums near entryways may also deter them.