Today 
Purple-striped green beetles, 8mm long, congregate among the leaves, which they feed on. The beetles lay elongated eggs beneath the leaves from September and continue to do so on warm days right through winter. These hatch after a couple of weeks and the larvae feed on the plants for about three weeks before entering the soil to pupate. Two weeks later the adults emerge and continue munching through the leaves and laying their eggs.
Solution
Organic
Pick off the adult beetles and larvae by hand and destroy.
Chemical
Spray with an insecticide - bifenthrin, thiocloprid or imidacloprid - between late summer and spring. Avoid using insecticide when the plants are in flower as bees may also be killed.
