Ladybug hypersensitivity among residents of homes infested with ladybugs in Kentucky

There have been isolated case reports of hypersensitivity to the ladybug species Harmonia axyridis. Entomologists now report a rapid increase in ladybug numbers, giving rise to increasing complaints of residential infestations.

To determine whether ladybug infestation of homes causes hypersensitivity among residents and to estimate the prevalence of self-reported ladybug allergy in this population.

This pilot observational study was conducted using an anonymous survey.

The participation rate was 59% (99/167). The incidence of self-reported allergy symptoms in this population was 77% (95% confidence interval [CI], 67%-85%). The prevalence of self-reported ladybug allergy was 50% (95% CI, 39%-60%). Of all the respondents, 19% (95% CI, 12%-28%) reported allergy symptoms on direct contact with ladybugs and 31% (95% CI, 22%-41%) reported the use of extra allergy medications during times of infestation. The correlation between worsening of allergy symptoms and time of infestation was significant for spring, fall, and winter infestations (P = .02, P = .001, and P < .001, respectively).

To our knowledge, this is the first study to estimate the prevalence of ladybug hypersensitivity, which was found to be 50% by self-report among people with home infestations. These results suggest that the ladybug could be a significant cause of respiratory allergy in heavily infested homes. Further studies using diagnostic testing to confirm allergy are now indicated. We recommend that patients with spring, fall, and winter allergies be asked about ladybug infestation and that ladybug reagents be made available for diagnostic testing.