Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 108

228

Family PSEUDOCOCCIDAE (mealybugs)

Typically elongate-oval insects, with poorly developed
5- to 9-segmented antennae but well-developed legs;
body covered in a flocculent or mealy waxen secretion.
Females elongate-oval and woodlouse-like; males rare
and often unknown.

Balanococcus diminutus (Leonardi)
syn. Trionymus diminutus Leonardi;
T. calceolariae (Maskell)
New Zealand flax mealybug
An Australasian species, associated mainly with New
Zealand flax ( Phormium tenax ) but also attacking
Cordyline australis . Introduced on such plants to other
parts of the world, including northern Europe; often
noted in south-western England.

228 Colony of ash scale ( Pseudochermes fraxini ) on Fraxinus .

Pseudochermes fraxini (Kaltenbach) ( 228 )
syn. Apterococcus fraxini (Newstead)
Ash scale
A local insect on ash ( Fraxinus excelsior ) trees, with
colonies occurring beneath white, felt-like masses of
wax on the stems of small trees and branches of larger
ones. Adult males appear from October to early
November, and crawl over the bark in search of
developing females. The males (0.9 mm long) are
wingless, and mainly orange to orange-yellow, with
black eyes. Mated orange-red females deposit eggs in
the spring and then die. The eggs hatch in mid-June.
Reddish first-instar nymphs then swarm over the bark
before settling down to feed and develop. Infestations
develop rapidly on trees placed under stress by the
removal of nearby shelter, and often occur on isolated
amenity trees in towns and cities.

DESCRIPTION
Adult female: 4-5 mm long; grey to purplish grey or
dark red, dusted with a white, waxen secretion that
forms long filamentous processes. Nymph: light grey,
dusted with white wax.

LIFE HISTORY
Eggs of this parthenogenetic species are laid in masses
within protective ovisacs formed mainly on the leaf
blades. The first-instar nymphs are very mobile,
particularly if arising from eggs deposited in
unfavourable situations; later instars and adults are
more or less sedentary, the insects often clustering
together at the leaf bases. There are several generations
annually, and all life stages often occur together.

DAMAGE
Infested plants are contaminated by vast quantities of
honeydew; in addition, masses of flocculent wax spoil
the appearance of plants. Attacked hosts are weakened
and may be killed.

Nipaecoccus nipae (Maskell)
Palm mealybug
Unsightly infestations of this tropical mealybug
sometimes occur in temperate regions on greenhouse-
grown palms, individuals tending to settle on the leaf
bases. Adults are about 3.5 mm long, salmon-pink in
colour, with discrete creamy-white waxen cones
distributed over the rather convex body.