Lady Bug Allergies

Along with the nuisance factor of having large numbers of ladybugs, (multi-coloured Asian lady beetles), in your home, the odd bite here and there and stain marks, it seems that they may also be a source of allergens. And if that is not enough, they are implicated in feeding on grapes in vineyards and causing off flavours in wine. In 2001, as high as 20% of the wines produced in Ontario were affected by off flavours from ladybugs. This occurs when the grapes are harvested and the beetles are crushed along with the grapes.

Ladybugs give off a yellowish fluid from their leg joints as a method of defense when they are alarmed. This fluid, which is an alkaloid, causes stains and gives off a strong odour. Research is now showing that it is this fluid which may be causing allergic reactions in some individuals. A study done in Kentucky and southern Ohio has shown a correlation between the presence of ladybugs and increased allergy symptoms. These symptoms included nasal congestion, eye irritation and asthma. Symptoms were noted in homes that had heavy infestations (hundreds of beetles) or after individuals had handled the beetles. In general, individuals with seasonal allergies tended to be bothered more by the presence of ladybugs than those with no allergies.

The news is not all bad. Asian lady beetles which were first introduced in the early 1900’s play an important role in the biological control of pests in various crops. They are a major predator of the Chinese soybean aphid which is a serious pest of soybean crops in Ontario. Ladybug infestations in homes tend to be worse in years when soybeans in the province have significant infestations of these aphids.