Developmental biology and larval morphology of Chromatomyia fuscula (Zetterstedt) (Dipt., Agromyzidae)

The egg stadium of Chromatomyia fuscula (ZETTERSTEDT, 1838) (collected in Southern Norway) takes 4.5 days to hatch in June. The first instar larva (4.5-6.5 days) is metapneustic and the 2nd instar (6.5-9.5 days) is amphipneustic. The third instar has a pair of fan-like anterior spiracles with 18-20 digits each and a pair of posterior spiracles with 5-8 pores, each arranged in 2 rows. Pupariation takes place between the 12.5th and 15th day. During sclerotization and melanization firstly blackish "V" shape stripes develop on the ventral puparial side which enlarge later and merge to a wide black spot, but the dorsal side remains usually yellowish and transparent. Pupal moult occurs within the puparial shell 2-3 days after the white pre-puparial phase. After 4 days, the imaginal transformation takes place. After a further 5 days, the pharate phase adult with white eyes turns to the orange eye phase. The following day, the red eye phase occurs. The next day bristle formation takes place: wings and bristles are greyish, later turn to black. During the following 1-2 days, the procuticle phase adult emerges. Adults are not attracted to either young or old spring barley plants, but look for a sheltered, humid place. A very long imaginal aestivation and hibernation period starts, which is a very uncommon overwintering strategy among agromyzid flies.