(1) Peach leaves attacked by Black Peach aphis. (2) Colony of Cabbage aphis on leaf. (3) Stem of insignis pine attacked by Chermes. (4) Grape Phylloxera and galls on vine roots. (5) Grape Phylloxera galls on vine leaf. (6) Woolly aphis on apple twig. (7) Galls of Poplar aphis. (Figs. 1, 2 and 6 by W. C. Davies; Fig. 4. after U.S. Dept. Agric.; Fig. 5. after N.Z. Dept. Agric.)] CABBAGE APHIS(_Brevicoryne brassicæ_).--The cabbage aphis, or cabbage green fly, is widely distributed throughout the world, and has become a serious pest in New Zealand, causing considerable damage to cruciferous crops; it infests rape, turnip, cabbage, Brussels sprouts, cauliflower, as well as related weeds, such as wild mustard, shepherd’s purse and watercress. Most damage is done during dry seasons, when the plants succumb more readily to attack; if the insects are numerous, they cause the leaves to curl, and give a greyish appearance to infested plants, which may become flaccid and sticky from the copious honey-dew of the insect. The wingless forms are bluish in colour and coated with a greyish powder, but the winged females have the head and thorax black and the abdomen greenish (Fig. 9, 2). In New Zealand all stages may be found throughout the year on winter crucifers or on weeds, though reproduction is retarded during the winter; in the spring the winged females fly to young crops. In very cold climates eggs are laid in the autumn, and these survive the winter. The cabbage aphis is attacked by a number of parasites, and usually the brownish empty shells of a large number that have been destroyed by a small parasite are to be found at any time; other important enemies are the hover-flies, the eleven-spotted ladybird beetle, and the Tasmanian aphis-lion. The insect can be controlled by spraying with nicotine-sulphate to which soap has been added.