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Aphids on nettle
Blackman & Eastop list about 18 species of aphids as feeding on common stinging nettle (Urtica dioica) and 11 on small nettle (Urtica urens) worldwide, and provides formal identification keys for aphids on Urtica.
Most of these, such as Neomyzus circumflexus (crescent-marked lily aphid) and Myzus ornatus (ornate aphid), are polyphagous and feed on a wide range of herbaceous plants. They are not commonly found on nettles, and we have yet to find them on this host. Hence we restrict this page to the two nettle specialists, both of which are common or abundant in Europe and North America. Assistance on differentiating the two species of nettle that we consider is given below.
Aphis urticata (Dark green nettle aphid)
Aphis urticata is a small to medium size aphid. Early generations of the dark green nettle aphid are dark bluish-green often mottled with a lighter green (see first picture below) with no wax covering. Later generations of dwarf summer apterae become pale yellowish. The abdominal dorsum is either unsclerotized or rarely with rather narrow dusky bands across tergites 7-8. The longest posterior hairs on the femora, and the longest tibial hairs, are always much longer than the least width of the tibiae. The pale tapering siphunculi are usually slightly dusky at the tips, and are 0.90-1.78 times the length of the cauda (cf. Microlophium carnosum which has long tapering siphunculi with flared apices, 2.3 to 3.1 times the length of the cauda). The tongue shaped cauda is also pale. The body length of adult Aphis urticata apterae is 1.7-2.2 mm.
Aphis urticata alatae (see second picture above) have more sclerotization than apterae with bands across tergites 7-8 and some marginal sclerites. The siphunculi of alates are uniformly dusky and cylindical. The body length of the alate is 1.5-1.8 mm.
Early generations of the dark green nettle aphid form dense colonies on stems and leaves of the common nettle (Urtica dioica). The dwarf summer form of Aphis urticata can be found scattered on the undersides of the leaves. The dark green nettle aphid is generally common, and sometimes abundant, throughout Europe and into Asia.
Microlophium carnosum (Common nettle aphid)Microlophium carnosum is a large spindle-shaped aphid. Apterae (see first picture below) are various shades of green, pink or reddish purple. The antennae are curved and much longer than the full body length. The antennal tubercles are smooth, with the inner faces divergent. Microlophium carnosum siphunculi are long and tapering with flared apices, 2.3 to 3.1 times the length of the cauda (cf. Aphis urticata which has pale tapering siphunculi, usually slightly dusky at the tips, which are 0.90-1.78 times the length of the cauda). Body length of the adult aptera is 3.1-4.3 mm.
There is a sexual stage in the life cycle and there is no host alternation. Common nettle aphids live on stems and leaves of common nettle (Urtica dioica). Microlophium carnosum is generally common and often abundant throughout Europe and Asia east to Mongolia, Africa & North America. It is not ant-attended.
Species of nettle
Two species of nettles occur commonly in Britain, the common or stinging nettle (Urtica dioica) and the small nettle (Urtica urens). The common nettle is a herbaceous perennial with creeping rooting stems which produce upright leafy stems up to about 150 cm tall with leaves about 6 cm. Male plants have flower clusters that stick out, whilst female plants have flower clusters that hang down.
The whole plant has large numbers of stinging hairs. These are the longer white hollow hairs visible in the picture below - the irritant poison is produced in the bulb at the base of each hair. If you brush against the plant, the tips of the hairs break off leaving a sharp point which can then penetrate the skin and inject the poison.
The small nettle is less common and is smaller, usually less than 30 cm tall with leaves only about 4 cm in length. It has more deeply excised leaves and both male and female flowers in the same cluster