Tropicomyia theae

Tropicomyia theae (Cotes in Green, 1896)

Identification of Tropicomyia species is very difficult. Many species differ only in very slight characters of the male aedeagus. Moreover, due to insufficient availability of type material the status of several species is not fully clarified. Hence in most cases an approximation to the species can only be achieved by the comparison of pictures of the male genitalia (see also the Genus Tropicomyia) and, to some extend also the geographical range. Identification by external characters only is absolutely impossible.

Adults (Spencer, 1973)
Last section of M3+4 distinctly shorter than penultimate; species rather large with 2 mm wing length; mesonotum moderately shining, black.
Male terminalia
Terminal tubules of ejaculatory duct rather long; distiphallus slender.
Immature stages
Larva and puparium in concordance with the general description given under Genus Tropicomyia. For the larvae sensu Singh and Beri, 1971 these authors found some slight larval characters, which were useful to separate this species from Tropicomyia atomella:
Frontal process rather small and bifid; upper and lower part of dorsal arm of cephalopharyngeal skeleton posteriorly fused. However, to my personal experience with agromyzid larvae such characters should be handled with care since they widely depend on the age and condition of the larva and on the method of preparation.

The larvae produce always epidermal leaf mines on the upper side of the leaf. There are often several larvae on the same leaf.

Tropicomyia theae is a polyphagous species, Spencer, 1990 listed 7 plant families known to include hosts. Among them are the cultivated plants Camellia sinensis (tea) and Coffea arabica L. (coffee).

Known from Sri Lanka, Indonesia, India, Seychelles. From Japan, another closely related species Tropicomyia styricicola (Sasakawa, 1954) was described. According to Spencer, 1973 the two species are distinct. Whether or not T. theae itself occurs in Japan is so far unknown.

Singh and Beri, 1971 observed the species being widespread on tea plants in Assam (India). However, the abundance was so low that the authors had problems to collect a sufficient number of larvae for their research. A similar conclusion was drawn by Spencer, 1973 citing further old literature. Conversely, Chacko and Ramanarayana, 1976 reported an heavier attack of coffee plants (referred to as T. coffeae) that had been managed by chemical insecticides.