Filter Fly Larva (Psychoda alternata) from Human Sputum

Abstract

Filter flies (Diptera, Psychodidae) are common pests around homes (Mallis 1960) and sewage disposal plants (Scott 1961). T'hey are reported infesting the human bladder (Chin 1959) and stomach (Okada 1927). Bronchial asthma caused by filter fly adults is reported (Ordman 1946). In July 1963, a mature larva of Psychoda alternatca Say (Fig. 1) was recovered from the sputum of a man in Macon, Georgia. The source of this infestation is undetermined. A mature larva would be 11-17 days old based upon 70?F developmental studies. T'he recovered larva was not noticeably damaged or digested. Psychoda alternata occurs from Florida to Massachusetts west to Washington and California. It breeds in polluted shallow water or highly moist organic solids, especially sewage filters, exposed sewage, plumbing traps, water pipes, wash-water overflow, compost, and bird's nests. The female lays a gelatinous mass of 20-100 eggs which hatch in 32-48 hours. Larval stages occupy 9-15 days. The pupal stage requires 20-40 hours. Adults are weak fliers. They rest in shaded areas or on foliage during the day. They feed on nectar or polluted water, are attracted to lights, and have been reported entering houses in large numbers.