Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 90

Adelges nordmannianae (Eckstein)
syn. A. neusslini (Börner); A. schneideri (Börner)
Silver fir migratory adelges
This dark brown to black adelgid is an important pest of
young common silver fir ( Abies alba ); heavy
infestations also occur on other species, including
Caucasian fir ( A. nordmanniana ) and Cilician fir
( A. cilicica ). Nymphs overwinter on the shoots, and
eventually mature and deposit clusters of brownish-
orange eggs. These hatch at about bud-burst. Nymphs
then feed on the needles, and commonly cause
significant discoloration, stunting and distortion;
severely infested trees may be killed. Infestations may
also occur on the stems of host trees but, unlike Adelges
piceae , with which this species is often confused, very
little waxen 'wool' is produced. Several generations
may persist on fir-tree hosts but, in summer, winged
migrants appear. These disperse to spruce ( Picea ) trees
where, in the following year, small, rounded terminal
galls (about 10 mm across) are eventually produced.
Colonies of this species produce considerable quantities
of honeydew.

are produced and these fly back to spruces, where their
eggs hatch into summer, sexual forms. Progeny of the
latter overwinter and eventually produce nymphs which
initiate the next generation of pineapple galls.

Pineus pini (Macquart) ( 189 )
Scots pine adelges
A widespread and common, but minor, pest of Scots
pine ( Pinus sylvestris ); other two-needled pines are also
hosts. Present throughout Europe, and introduced with
the host plant to all other parts of the world.

DESCRIPTION
Apterous female (sisten): 1.0-1.2 mm long; dark
brown to dark red, and almost spherical; head and
prothorax heavily chitinized; antennae 3-segmented;
abdomen with four distinct pairs of spiracles and an
ovipositor. Alate female (sexupara): 1.0-1.2 mm long;
mainly reddish grey; antennae 5-segmented; fore wings
1.4-1.7 mm long, hyaline and with the veins often
tinged with red. Egg: oval and orange.

LIFE HISTORY
Nymphs, that hatch from eggs deposited in the autumn,
overwinter and mature in the following March. They
then deposit clusters of eggs, the progeny of which
invade the new shoots and eventually develop into
either winged or wingless forms. The former migrate to
other sites from the end of May to late June, whereas the
latter initiate a further wingless generation on the
'parent' plant; all females are oviparous. There may be
three or more wingless generations each year. Colonies
persist mainly on the bark of the shoots and youngest
stems, and the aphids produce masses of white, fluffy
'wool'.

Adelges piceae (Ratzeburg)
Silver fir adelges
Restricted to silver fir ( Abies ) trees, and most
commonly present on species of North American origin,
e.g. alpine fir ( A. lasiocarpa ), balsam fir ( A. balsamea ),
grand fir ( A. grandis ) and noble fir ( A. procera ).
Colonies occur mainly on the stems, the dark brown or
blackish insects (unlike Adelges nordmannianae , with
which - when on common silver fir ( Abies alba ) - this
insect is often confused) producing noticeable quantities
of waxen 'wool'. Infested tissue often becomes
distorted and swollen; in severe cases, growth is
significantly affected and host trees may be killed.

DAMAGE
The presence of waxen 'wool' disfigures host plants and
is particularly unsightly on young garden and nursery
trees.

Adelges viridis (Ratzeburg) ( 186-188 )
syn. A. laricis (Hartig)
A spruce pineapple-gall adelges
Generally common on spruce ( Picea ) trees, especially
Norway spruce ( P. abies ) and Sitka spruce
( P. sitchensis ), forming pineapple-like galls on the
shoots; these are similar to those produced by Adelges
abietis , but tend to be more elongated and usually
completely encircle the shoots, stopping further growth.
Winged individuals emerge from the galls in July
(earlier than Adelges abietis ), and then migrate to larch
( Larix ) where eggs, the overwintering stage, are laid.
Light green, wingless forms develop on larch from mid-
April onwards (earlier than other larch-infesting
adelgids), causing a characteristic kinking of the
needles. Eventually, light green or yellow, winged forms