Of all the caterpillars that feed on cabbage, the cabbage moth caterpillar has the potential to cause the most feeding damage. The caterpillars can reach up to 5 cm in length. Other brassica crops may also be damaged by the cabbage moth.
Cabbage moth [Mamestra brassicae]
Cabbage moth - image 1
The cabbage moth has two generations. Egg deposition occurs in May/June and from August to September. The 2nd generation causes the most damage.
Pattern of damage
Caterpillar feeding causes damage to the leaves and boring into the plant. This leads to soiling with frass and eventually to rot. The moths are gray-brown with wavy lines. The larvae (caterpillars) are initially green and eventually turn dark (Picture 1).
Row covers can reduce infestation. Control with insecticides at the beginning of infestation is advisable, but it is first necessary to establish that the economic threshold has been reached.