Seasonal inhalant insect allergy: Harmonia axyridis ladybug

The exotic Asian lady beetle, Harmonia axyridis, has become a prominent cause of seasonal inhalant allergy (allergic rhinitis, asthma, and urticaria) in the last two decades in North America and Europe after being introduced into the environment as an agricultural pest-control predator.

Seeking winter hibernation sites, ladybug swarms will invade human habitats in the fall. Large fall swarms and smaller spring dispersions produce corresponding peaks in ladybug allergy. Ladybug allergy prevalence in endemic areas has been reported as high as 10%. For some individuals ladybug allergy is their first expression of allergic disease. Exposures at home, work, school, and in other settings may be sensitizing. Ladybug hemolymph is the primary source of allergens. Har a 1 and Har a 2 major ladybug allergens have been characterized. 'Reflex bleeding' from tibiofemoral joints (for communication and during alarm) disperses these allergens.

Ladybug skin testing should be routine in endemic areas. Avoidance continues to be the first step in treatment. Allergen vaccine therapy may be effective, but a commercial extract of H. axyridis is needed.