Agriculture Reference
In-Depth Information
of different morphs and alternation of host
plants.
EXAMPLES:
Adelginae -
Adelges abietis
and
A. viridis
(spruce pineapple-gall aphids);
Pineinae -
Pineus pini
(Scots pine adelges).
22. Family PHYLLOXERIDAE
(phylloxerans)
(p. 123)
Fig.
41 Antenna of an alate aphid - subfamily
Pemphiginae.
A small group of insects, structurally similar to
adelgids but alates with just three antennal seg-
ments and wings held flat when in repose; wax (if
present) never flocculent.
EXAMPLES:
Viteus vitifoliae
(grape phylloxera),
Phylloxera glabra
(oak leaf phylloxera).
Superfamily COCCOIDEA (scale insects)
A
diverse group, demonstrating considerable
sexual dimorphism. Larsi, if present, usually
1-segmented and with a single claw (cf.
superfamily Aphidoidea). Males often rare or
absent; if present, typically short-lived, small or
minute; mouthparts vestigial; apterous or with
just one pair of wings; body often terminates in a
caudal spine and a longer pair of cerci
(Fig.
43).
Adult females wingless, usually sedentary and
apodous; often scale-like or cushion-shaped.
First-instar nymphs (crawlers)
(Fig.
44) often
very mobile, later instars usually becoming more
or less sedentary. Many species excrete consider-
able quantities of honeydew.
Fig.
42 Venation of an alate adelgid - family
Adelgidae.
Cu
1
and Cu
2
veins on forewings and hindwings
close-set and noticeably divergent: subfamily
Pemphiginae - venation of forewing reduced
(Fig.
41) (cf. Fig. 39). Associated primarily with
trees and shrubs, often forming galls, but some
species migrating in summer to herbaceous
plants or grasses, including certain crops.
EXAMPLES:
Eriosomatinae -
Eriosoma
lanigerum
(woolly aphid); Pemphiginae -
Pemphigus bursarius
(lettuce root aphid).
23. Family DIASPIDIDAE (armoured scales)
(p. 123)
21. Family ADELGIDAE
Body of female protected by a hard, scale-like
(often more or less circular or mussel-shaped)
covering
(Fig. 45a)
formed from wax and cast-off
nymphal skins; legs absent; hind segments of
body fused to form a pygidium
(Fig. 45b).
Male
scales (if present) typically smaller and narrower
than those of females, and often distinctly ribbed
longitudinally.
EXAMPLES:
Aulacaspis rosae
(rose scale),
Lepidosaphes ulmi
(mussel scale).
Entirely conifer-feeding, aphid-like insects; un-
like true aphids, antennal segments short and
wing venation reduced: Rs vein of forewing ab-
sent; hindwings often with just one, unbranched
vein
(Fig.
42); siphunculi absent; females entirely
oviparous and covered in flocculent masses of
wax; alates with five antennal segments. Life-
cycles are very complex, often involving a variety
