Chromatomyia nigra (Meigen, 1830)
Male genitalia distinct but without dissection of the male genitalia, confusion with the other grass mining species Chromatomyia fuscula may occur.
IMPORTANT CHARACTERS
Adults
Wing length: 2 - 2.7 mm. Female: Third antennal segment much shorter than broad. Frons variable either yellow or dark. Frontorbital setulae rather long. Arista of third antennal segment gradually tapering. Shape of third antennal segment important!... Usually three large frontorbital setulae present, of these the anterior one is inwards directed. Sometimes a fourth smaller one may be found.
Both sexes: Acrostichal setulae present.
Pubescence of the male's eye more densely than in fuscula (Iwasaki, 1995, fig.). (High magnification)
Immature stages
Anterior stigma with rather long stalks distinctly longer than Chromatomyia horticola and Chromatomyia fuscula (figs Spencer, 1973, SEM figures available). Pupation takes place within the mine.
BIONOMICS
The larva forms a narrow, whitish linear mine, which can differ in size and shape depending on the host grass. There are several generations per season.
HOST PLANTS
Avena sativa L., Hordeum vulgare L., Secale cereale L., Triticum aestivum L., also many wild grasses (Spencer, 1973). It feeds on several species with distinctly different habit and leaf shape.
DISTRIBUTION
Widespread throughout Europe but apparently absent from northern Scandinavia and Scotland; Japan, India (Sandhu and Deol, 1975). Records from Canada: Vancouver; USA: Oregon, Washington (Spencer, 1973).
ECONOMIC IMPORTANCE
In Europe Chromatomyia nigra is common on cultivated cereals and pasture grasses but only of minor significance among other grass mining agromyzids. In contrast the species is considered as serious pest (Sasakawa, 1953). The same author (Sasakawa, 1954) found, that more eggs are laid on early maturing varieties.