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Pemphigus gairi and Pemphigus phenax
Poplar pouch gall aphidsOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution:
In spring Pemphigus gairi and Pemphigus phenax form yellowish or
reddish elongate pouch-shaped galls on black poplar (Populus nigra) (see first picture below). The galls are usually more or less in the middle of a leaf, and are on or near the midrib. The slit-like opening on the underside extends over the entire length of the gall. (cf. Pemphigus populinigrae which induce broader pouch-shaped galls with the opening extending over part of the gall).
The offspring of the fundatrix develop into winged viviparae (see second picture above) that emerge from these galls in summer through an opening on the underside of the leaf. They have a black head and pterothorax, small siphunculi and a rather elongate greenish wax-dusted abdomen.
Pemphigus gairi host alternates between poplar and fool's parsley (Aethusa cynapium). In summer they live on the roots of the secondary host. Pemphigus gairi has been found in England, Czech Republic and Ukraine, but it probably occurs widely in Europe.
Pemphigus phenax host alternates between poplar and the roots of wild and cultivated carrots (Daucus carota). Apterae on carrot roots are pale lemon-yellow to yellowish white with white wax. Colonies may also persist parthenogenetically on carrots that remain in the ground through the winter. Pemphigus phenax is found in northern Europe (England, Denmark, France, Germany, Netherlands, Sweden), and is also recorded from Turkey and west Siberia.
Biology & Ecology
The galls of probable Pemphigus phenax that we have found are quite variable in appearance, but all are predominantly red with a little yellow on the sides.
In May, most of the galls contained only the wax covered fundatrix (see picture below).
We removed the wax from the one in the first picture below to show distinguishing features. The fundatrix is green or greyish green and has no siphunculi. The grey aphid in the second picture below is most likely an old fundatrix which has lost most of its waxy covering naturally.
A few galls were evidently older and contained many pale yellow immature alatae with varying degrees of wax coverage.
The white wax patches mark the sites of the wax glands.
The picture below shows the emergent alate. They have small siphunculi and a rather elongate greenish wax-dusted abdomen.
Other aphids on same host:
Pemphigus phenax has been recorded from 2 Populus species (Populus ×berolinensis, Populus nigra), Pemphigus gairi has been recorded from 1 (Populus nigra).