Biology Reference
In-Depth Information
Family
PHYLLOXERIDAE
LIFE HISTORY
The winter is passed in the egg stage in crevices in the
bark of oak trees. In spring, nymphs invade the new
growth to feed on the underside of the leaves. Once
maturity is reached, eggs are deposited in small circles,
all female individuals being oviparous. There are
several asexual generations throughout the summer.
However, in the autumn, smaller-bodied, winged sexual
forms are produced. After this sexual phase, mated
females eventually deposit the winter eggs.
A small group of insects, structurally similar to the
Adelgidae but alates with just three antennal segments.
Phylloxera glabra
(von Heyden) (
191-193
)
Oak leaf phylloxera
A generally common but minor pest of English oak
(
Quercus robur
). Widely distributed in Europe.
DESCRIPTION
Apterous female:
0.70-0.85 mm long; yellowish,
marked with orange; oval-bodied and scale-like.
Egg:
0.25 mm long; elongate-oval, yellow and shiny.
Nymph:
similar to adult but smaller.
DAMAGE
Infestations cause yellow and brown spotting of leaves;
this sometimes leads to a general browning of the
foliage, followed by premature leaf fall. Infestations on
established trees are usually of little or no importance
but persistent attacks on young trees reduce plant
vigour.
191
192
193
191
Colony of oak leaf phylloxera (
Phylloxera glabra
) on
Quercus
.
192
Eggs of oak leaf phylloxera (
Phylloxera glabra
).
193
Oak leaf phylloxera (
Phylloxera glabra
) damage to leaf
of
Quercus
.
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