Family Pemphigidae

Aploneura lentisci (Passerini)

Colonies of this species occur on the roots of grasses throughout the year, and are most obvious from May to October, but damage caused is of little or no significance. The aphids produce considerable quantities of whitish wax that accumulates around the aphids in cottonwool-like masses. Winged forms occur in large numbers in the summer; in Mediterranean areas, these are able to locate Pistacia lentiscus, the primary host, upon which the species then overwinters. Apterae are 1-3 mm long, spindle-shaped and mainly pale to ochreous yellow, with dark, very short legs and antennae (Fig. 194).

Eriosoma lanigerum Woolly aphid

(Hausmann)

Fig. 194 Anterior part of body of Aploneura

Infestations of this notorious pest occur mainly on apple but may also develop on other trees and shrubs (Rosaceae), including various ornamentals. The aphids produce considerable quantities of waxen 'wool', which often contaminates shoots, leaves and fruits. The aphids also cause significant galling of infested wood and heavy infestations lead to considerable disfigurement and disruption of growth; damage is of particular importance on young trees. The often walnutlike galls may split open, allowing canker and other diseases to gain entry.

BIOLOGY

This aphid remains on apple throughout the year. The winter is passed as bare (wax-less) nymphs that shelter in cracks or crannies in the bark of host trees. Activity is resumed in the spring and colonies soon develop beneath conspicuous masses of whitish, waxen 'wool', especially on the shoots, spurs and branches. There are several generations throughout the summer months, and colonies at this time often develop on sucker growth and water shoots. Small numbers of winged aphids may be produced in July but they are of only minor importance in spreading infestations. Egg-laying females (oviparae) appear in September but any eggs they deposit fail to hatch, aborting the sexual phase. Wax-covered colonies of parthenogenetic females persist well into the autumn and finally die out as the nymphs that will overwinter enter hibernation

Fig. 194 Anterior part of body of Aploneura

DESCRIPTION

Aptera 1.2-2.6 mm long, soft-bodied, purplish-brown, covered with masses of white, mealy wax; antennae short, with the third segment elongated (Fig. 195a); siphunculi pore-like.

8 It is thought that colonies persist throughout the winter on the roots of host trees but accounts from authors differ as to whether there is a regular seasonal migration from the aerial parts of host plants to the roots and back.

Fig. 195 Antennae of apterous aphids, family Pemphigidae: (a) woolly aphid, Eriosoma lanigerum; (b) carrot root aphid, Pemphigus phenax.

NOTE Other species of Eriosoma are also associated with fruit crops, e.g. E. ulmi (L.) (currant root aphid) which, in summer, breeds on the roots of Ribes, and E lanuginosum (Hartig) (elm balloon-gall aphid) which, also in summer, occurs on the roots and basal parts of the trunks of pear trees. Both species overwinter on Ulmus, the primary host.

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