The larvae are about up to 7 mm long and dirty-white. They have a dark-brown head and three pairs of legs, and two small dorsal processes at the abdomen. The body is covered with bristly-haired dark spots. The beetles are about 3-4.5 mm long and blue-black with a metallic shimmer (Picture 1). They have finely punctured ridges on the wing cases and a good ability to jump due to their strong hind legs.
Cabbage stem flea [Psylliodes chrysocephala]
Cabbage stem flea - image 1
On oilseed rape and other cruciferous species
Pattern of damage
The young rape leaves have pitting caused by the beetles. Much more harmful, however, are the wounds caused by the larvae feeding in the inside of the stems and petioles. The latter rip opens slightly, especially if water has entered through the wounds prior to frost. If the vegetation points are also destroyed by the wounds caused by the pest, the entire plant dies off.
The cabbage stem flea is common in most oilseed rape growing areas and affects the rapeseed from the emergence of the crop in the fall. As typical winter breeders, the females can also lay their eggs at low temperatures (up to about 6 °C) so that the process may continue until spring.