Aphelinus mali - emergence from mummified aphids

A. mali parasitises woolly apple aphids (including winged forms) on the above-ground parts of apple trees but has rarely been reported on the roots. Percentage parasitism above ground varies greatly. It often increases over the summer, such as from about 10-20% in spring to 80-90% in autumn. All the aphids in these pictures are parasitised. The aphid host turns black and stops producing wool, and this makes parasitised aphids easily visible. Emergence holes can be seen in the lefthand picture (see arrows). A. mali may also parasitise a high proportion of aphids which have infested the fruit in late summer (right).