Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 107

Family ERIOCOCCIDAE (felt scales) flocculent masses of whitish wax, each insect

depositing about 250 eggs before dying. The eggs hatch
from late August onwards, first-instar nymphs
migrating onto the leaves to feed. Second-instar nymphs
eventually overwinter, resting in sheltered places on the
bark of host trees. In the following spring, the nymphs
invade the young shoots and foliage. Later, they move
onto the trunk and larger branches where they settle
down to mature. There is one generation annually.

Cryptococcus fagisuga Lindinger ( 226-227 )
syn. C. fagi (Baerensprung)
Beech scale
A generally abundant pest of beech ( Fagus sylvatica ).
Widely distributed in Europe; accidentally introduced
into North America in the late 1800s, where it has since
become a significant pest.

DESCRIPTION
Adult female (scale): 0.75-1.0 mm long; hemispherical
and pale lemon-yellow, coated with white flocculent
threads of wax. Egg: 0.15 mm long; pale yellow. First-
instar nymph: 0.25 mm long; lemon-yellow, with three
pairs of legs and 5-segmented antennae.

LIFE HISTORY
This species is parthenogenetic and has a single
generation. Eggs are laid from June to August, hidden
under the protective waxen 'wool' in small string-like
clusters of up to eight. They hatch 6-7 weeks later. The
very active first-instar nymphs either burrow beneath
the remains of adjacent dead scales or swarm over the
trunk and branches before settling down in suitable bark
crevices. They then overwinter before moulting to the
entirely sedentary second nymphal stage. These second-
instar nymphs eventually moult to the adult stage,
individuals usually reaching maturity in early June. The
scales produce considerable quantities of white, waxen
'wool', and often cover considerable areas of the main
trunks and branches. On heavily infested sections of
bark, the scales commonly overlap the shrivelled, black
remains of previous generations.

226

DAMAGE
Scale-encrusted bark disfigures ornamental trees, but
infestations usually have little or no direct effect on the
growth or well-being of their hosts. However, in some
regions (e.g. Denmark and North America) attacks are
associated with pathogenic fungi ( Nectria spp.) and lead
to the decline and eventual death of affected trees.

226 Beech scale ( Cryptococcus fagisuga ).

227

Eriococcus spurius (Modeer)
syn. Coccus ulmi (Linnaeus); Gossyparia
spurius Modeer
Elm scale
A widely distributed species, associated with elm
( Ulmus ), sometimes forming noticeable encrustations
on amenity trees in towns and cities. The adult females
( c . 2. mm long) are dark red and oval, with a short pair
of anal papillae. They occur during the summer on the
bark of the trunks and main branches amongst 227 Colony of beech scale ( Cryptococcus fagisuga ) on Fagus .