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Scarce variegated oak aphidIdentification & Distribution Biology & Ecology Damage & Control
Note: Lachnus longirostris was originally confused in the literature with Lachnus iliciphilus, a species of southern France. There is some evidence that Lachnus longirostris is conspecific with Lachnus pallipes but, until this is confirmed, we continue to treat them as separate species.
Identification & Distribution:Apterae of Lachnus longirostris are shining dark reddish to blackish brown. The siphuncular cones are rather small. The abdominal dorsum is densely haired with long, fine-pointed hairs. The middle parts of the tibiae are pale and the antennae are 0.4 - 0.5 times the body length. In addition the hind tibia has hairs on the ventral side which are often longer and finer distally, but not with some hairs 2-3 times longer than others. Lachnus longirostris alatae have a pattern of forewing pigmentation similar to Lachnus roboris, but with a more extensive clear area between Rs and media. Body length is 2.4 - 5.0 mm.
The first image shows the shining blackish-brown Lachnus longirostris aptera. Note especially the hairy dorsum and the pale middle parts of the tibiae. These characteristics can be used to distinguish both apterae and alates of Lachnus longirostris from Lachnus roboris on oak. In addition the wing patterning of alates is slightly different.
Scarce variegated oak aphids are found on twigs and branches of oak (Quercus spp.). A very similar species Lachnus pallipes occurs on beech. The differences between the two species are mostly size-related and they are considered by some authorities to be the same species feeding on different hosts. Lachnus longirostris is widely distributed in Europe.
Biology & Ecology:
The overwintering eggs of Lachnus longirostris hatch in early summer and develop into small colonies. We have only found this species once and then in low numbers. The images below shows a young colony in late June. The aphids are nearly always attended by ants, most often it seems by Formica spp. But in this case the aphids were very assiduously tended by jet black ants (Lasius fuliginosus).
There is little published information on this species. Lubiarz (2007) reported that over three years of research on Lachnus aphids on oak, Lachnus longirostris was only recorded twice with a total count of only 7 females. Lachnus roboris on the other hand occurred regularly and in large numbers.
The scarce variegated oak aphid has a sexual stage in its life cycle. Oviparae and small apterous males develop in October. Egg laying takes place in autumn after mating.
Damage and control
The aphid certainly causes feeding damage by rupture of the tree cambium, but since it is rather uncommon, it is unlikely that control of this aphid would ever be considered.