Drosophila digressa

Hawaiian Picture-wing Fly

FWS Focus


Drosophila digressa (picture-wing fly), a member of the family Drosophilidae, was described in 1968 by Hardy and Kaneshiro and is found only on the island of Hawaii (Hardy and Kaneshiro 1968, pp. 180–1882; Carson 1986, p. 3–9). This species is small, with adults ranging in size from 0.15 to 0.19 in (4.0 to 5.0 mm) in length. Adults are brownish yellow in color and have yellow-colored legs and hyaline (shiny- clear) wings with prominent brown spots. The wings of D. digressa differ from all known Hawaiian Drosophila by having a small brown spot at the middle of vein R4+5, but lacking a brown mark in the middle of cell R1 (Hardy and Kaneshiro 1968, p. 180). This species is similar in structure to other Drosophilidae and other flies in that adults have three main body parts: head, thorax, and abdomen. One pair of antennae arises from the front of the head, between the eyes. A single pair of wings and three pairs of legs are attached to the thorax. The abdomen is composed of multiple segments. For a detailed technical description of the species characteristics please see Hardy and Kaneshiro (1968, pp. 180-182). Breeding generally occurs year round, but egg laying and larval development increase following the rainy season as the availability of decaying matter, which picture-wing flies feed on, increases in response to heavy rains. In contrast to most continental Drosophilidae, many endemic Hawaiian species are highly host-plant-specific (Magnacca et al. 2008, p. 1). Drosophila digressa relies on the decaying stems of Charpentiera spp. and Pisonia spp. for oviposition (to deposit or lay eggs) and larval substrate (Magnacca et al. 2008, pp. 11, 13; Magnacca 2013, in litt.). The larvae complete development in the decaying tissue before dropping to the soil to pupate (Montgomery 1975, pp. 65–103; Spieth 1986, p. 105). Pupae develop into adults in approximately 1 month, and adults sexually mature 1 month later. Adults live for 1 to 2 months. The adult flies are generalist microbivores (microbe eating) and feed upon a variety of decomposing plant material. Drosophila digressa occurs in elevations ranging from approximately 2,000 to 4,500 ft (610 to 1,370 m), in the lowland mesic, montane mesic, and montane wet ecosystems (Magnacca 2011a, pers. comm.).

Scientific Name

Drosophila digressa
Common Name
Hawaiian picture-wing fly
FWS Category

Location in Taxonomic Tree

Identification Numbers



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