The cherry aphid (Mizus cerasi) is an important pest of cherries in New South Wales. It infests the young foliage in late spring and early summer, and causes the terminal growth to wither and die. The foliage becomes covered with " honey dew " excreted by the aphids and on this a sooty mould develops. The fruit, also, may become covered with aphids and " honey dew," and thus be unmarketable. Trees that are allowed to remain heavily infested for several years may die or become unproductive.

From late October onwards, development is rapid and numbers of generations of aphids are produced. Only wingless females are present at this time, hut late in spring, winged females develop, and these may spread the infestation to uninfested trees. As the growth hardens late in December, infestation almost ceases, and very few aphids are present. Usually, only sucker growth around the margins of an orchard is infested during the summer months.

Late in the autumn, winged males and wingless egg-laying females develop and these mate, and the females lay the overwintering eggs. The winter eggs hatch from mid-August to early September. Development is slow, the aphids maturing at the time the buds burst in late September.