This book mainly deals with the population biology of deciduous tree-dwelling aphids, in particular, the sycamore aphid Drepanosiphum platanoidis. Information on the lime aphid Eucallipterus tiliae and Turkey oak aphid Myzocallis boerneri, which have not been studied in the same detail, is also presented. These aphids all belong to the subfamily Drepanosiphinae, fossils of which are first recorded in the late Cretaceous and make up a large proportion of the early Tertiary aphid fauna. Extant species of this subfamily are mainly host specific and most live on trees belonging to the Fagaceae, Ulmaceae, Aceraceae and Betulaceae. This subfamily of aphids is taxonomically well defined and not as polymorphic as the Aphidinae and Lachninae, which make up most of the present-day aphid fauna. From an ecological point of view this is important as it means they are easily identified, even in the field.

LIFE CYCLE

Most aphids live on only one species of host plant. The sycamore, lime and Turkey oak aphids belong to this group. They spend the winter months as eggs. In spring these hatch and give rise to nymphs that develop into the winged adults of the first generation, known as fundatrices. These adults are parthenogenetic and viviparous, and their offspring develop into other parthenogenetic viviparae. Several parthenogenetic generations occur in succession until the onset of autumn when the nymphs develop into unwinged egg-laying females and winged males. This is the sexual generation, which mate and produce the overwintering eggs (Figure 2.1).