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Bow-legged fir aphidIdentification & Distribution Biology & Ecology Damage & Control
Identification & Distribution:Cinara curvipes apterae are shiny or dull grey-black sometimes developing a covering of pale grey wax especially on the thorax and along each side of the dorsum. The abdomen usually has a broad sclerotized cross band on VIII. The siphuncular cones are black with the maximum diameter of the base of the cones more than 3 times the aperture. The coxae are dark brown to black. The fore and mid-tibiae are pale yellow but are dark at the apices. The hind tibiae are mainly dark but with a pale section at the base; they are long and curved giving the English name bow-legged fir aphid. The body length is 3.4 - 5.5 mm.
The oviparous female has a large pericaudal wax ring present. Cinara curvipes immatures may be more heavily wax-covered.
Cinara curvipes occurs on the trunk or branches of Fir (Abies spp.) They also feed on Cedar (Cedrus deodora) and a colony has been found on Pinus contorta. Oviparae and alate males occur in September-October. Cinara curvipes is widely distributed in USA, Canada, and Mexico. In the 1990s it was first recorded in the UK, and is now widely distributed in Europe
Biology & Ecology:
The bow-legged fir aphid forms large dense colonies on the trunk and branches of fir and sometimes cedar trees.
The image above shows part of a colony feeding on a young fir (Abies) in Sussex, UK in 2012. Note the extensive wax covering of the younger instars. Cinara curvipes was originally confined to North America, but was recorded in the UK in the 1990's at Kew Gardens in London (Martin, 2000 ). It soon spread to other parts of the UK as described by Baker (2009) who found a large, dense colony in Wales feeding on the underside of a grand fir (Abies grandis) branch.
The species also spread to continental Europe, although whether this resulted from the single UK introduction or multiple introductions is unclear. Jurc et al. (2009) document the spread of the species in Europe with the aphid now established in Germany, Serbia, Switzerland, Czech Republic and Slovakia.
Scheurer & Binazzi (2004) and Jurc et al. (2009) describe the bionomics of the bow-legged fir aphid in Europe. It lays winter eggs in November, but during mild winters the last generation can survive until the spring season and start to reproduce again in March. From mid April to late May their brood forms dense colonies of some thousand individuals and they suck on trunks and on the underside of branches. Colonies decrease in size in mid-summer as winged forms emigrate, but a second population peak is reached in late summer or autumn.
Large amounts of honeydew are excreted both in May and June and from August until November. This species is often attended by ants collecting the honeydew, as shown in the picture below where they are being attended by southern wood ants (Formica rufa).
Scheurer & Binazzi noted that honeydew from Cinara curvipes can be an important source of food for many ants, wasps and bees. Baker (2007) observed eyed ladybirds (Coccinella ocellata) adults close to the edge of the colony which he thought were predating aphids.
Damage and control
The status of the bow-legged fir aphid as a pest is unclear. It apparently does not cause economic damage to forests in its native North America, but in Europe it may have the potential to cause considerable economic damage.
Stary & Havelka (2008) record that the species reached pest status in many parts of Germany on white fir (Abies concolor). High numbers of the aphid were also observed in many parts of the Czech Republic, and pesticide treatments were used to suppress the new pest on exotic ornamental trees in gardens and parks. This was mainly because of aesthetic damage to trees as a result of the large amounts of honeydew and subsequent development of sooty moulds. More seriously Poljakovic-Pajnik & Petrovic-Obradovic (2002) reported that Cinara curvipes can cause the death of young white fir trees.