Some observations on blister beetles, family meloïdae, in Gambia, West Africa

Abstract

Blister beetles, (Family Meloidae), appeared each year from 1958 to 1962 in the Gambia at the end of the rains in Oct. -Nov., coincident with the hot and sticky postrains climate and the ripening of the savannah grass and domestic grains (millets). Cylindrothorax melanocephala, Psalydolytta fusca and P. substrigata were recovered, but only the last species appeared in pest densities especially in 1959. High density populations did not appear to be solely conditioned by heavy rainfall, but also by the presence of locust swarms in the previous year, whose eggs provided food for the triungulin larva. No experimental evidence was obtained that the beetle was capable of voluntarily secreting the blistering fluid which was only released when the insect''s integument was ruptered. The beetles were attracted to bright lights, and since they occurred at a time of the year when people stayed out of doors until late at night, the chances of accidental contact were greatly enhanced. The large light-stupefied insects crawling over bare skin were promptly swatted and the hemolymph of the crushed beetle was smeared over the perspiring skin. This resulted in the appearance of large bullae where the beetle was crushed and vesicular areas of linear dermatitis or macular patches where the blistering fluid was smeared. The blisters appeared 12-24 hr. after contact and were completely painless until broken, then they produced intense burning and itching Blistering occurred most commonly on the face, neck, chest, thighs and calves and often on the buttocks in young children who had sat on dead beetles during the day. Unlike the dermatitis produced by Staphylinid beetles, no cases of eye involvement were seen with Gambian Meloid beetles. If left untreated, the lesions were prone to infection and ulceration, if disinfected and kept clean, they healed satisfactorily, but more slowly than similar sized blisters produced by burning.