Biology Reference
In-Depth Information
Pemphigus phenax Börner & Blunck
syn. P. dauci (Goureau)
Carrot root aphid
This species overwinters as eggs on the bark of
Lombardy poplar ( Populus nigra 'Italica'). The eggs
hatch in the spring. Young aphids then move to the
unfurling leaves where they induce the formation of
midrib galls. Each gall becomes an elongate, somewhat
wrinkled, reddish swelling (often tinged with yellow
laterally), packed with numerous wax-secreting aphids.
In summer, winged forms migrate to cultivated and wild
carrot ( Daucus carota ), where dense colonies develop
on the roots amongst copious amounts of white waxen
'wool'. There is a return migration to poplar in the
autumn. Although the leaf galls on poplar trees may
attract attention, infestations are not of importance.
Pemphigus populinigrae (Schrank) ( 152-153 )
syn. P. filaginis (Boyer de Fonscolombe)
Poplar/cudweed aphid
Widely distributed in association with black poplar
( Populus nigra ). Eggs overwinter and hatch in the
spring. Young aphids then form bulbous, pouch-like
galls on the midrib of the leaves. Aphids (fundatrices)
initiating the galls are 2.6-2.8 mm long and mainly
green to greyish green, characteristically with 4-
segmented antennae. Colonies develop amongst a mass
of mealy wax, eventually giving rise to mainly brown-
bodied alates. These eventually escape from the galls
and fly to secondary (summer) hosts such as cudweeds
( Filago and Gnaphalium ). There is a return migration to
poplar in the autumn.
Pemphigus spyrothecae Passerini ( 154 )
Poplar spiral-gall aphid
Widely distributed in Europe (also recently introduced
to North America), and often common on poplar
( Populus ), especially Lombardy poplar ( P. nigra
'Italica'). Overwintered eggs hatch in the spring, and
aphids feed on the leaf stalks which then curl into
characteristic, distinctly spiral, pouch-like galls about
10 mm long. The galls, which become packed with
aphids, change from green through red to brown as they
mature, and are often abundant on ornamental trees.
Unlike its close relatives (see above), this species
spends its entire lifecycle on poplar.
152
152 Galls of poplar/cudweed aphid ( Pemphigus populinigrae )
on Populus .
153
154
153 Colony of poplar/cudweed aphid ( Pemphigus
populinigrae ) in gall on Populus .
154 Gall of poplar spiral-gall aphid ( Pemphigus spyrothecae )
on Populus .
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