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Black-tipped dark-veined birch aphidIdentification & Distribution Biology & Ecology Other species on the same host
Identification & Distribution:Apterae of Calaphis betulicola (see first picture below) are pale green or yellowish, with dark apices to antennal segments, femoro-tibial joints, tibial apices and tarsi. The head and thorax are pale. Calaphis betulicola antennae are longer than the body, and the terminal process is clearly longer than the base of the last antennal segment. Winged individuals (see second picture below) have characteristically darkened wing veins.
The siphunculi are pale but with dark brown tips (see first picture below) (cf. Calaphis flava which has the siphunculi pale or a little dusky at the flange). A more reliable means to distinguish Calaphis betulicola from Calaphis flava is to determine the position of the secondary rhinaria on antennal segment III. On Calaphis betulicola they are placed towards the middle of the segment (see second picture below) (cf. Calaphis flava which has the secondary rhinaria near the base of antennal segment III). The body length of Calaphis betulicola is 2.0 to 2.3 mm.
Calaphis betulicola is found on the undersides of leaves of range of Betula spp., including Betula pendula and Betula pubescens, usually on seedlings and small trees less than 1 meter high. It has also been recorded as living on Betula nana in Scotland and Sweden. It is distributed from northern Europe across Russia to China and Japan, as well as in the USA and Canada.
Biology & Ecology:
We have found Calaphis betulicola in two areas in Britain - at Dundreggan in the Scottish Highlands, and at Selwyn Wood in East Sussex. At Dundreggan they were in very large numbers on young growth of Betula nana in a plant nursery and a polytunnel (see pictures below).
Some of the dwarf plants in the nursery had prematurely aged with bright red leaves, and they were similarly infested with Calaphis betulicola (see picture below).
Holman (1996) thought Calaphis betulicola was only a vagrant (accidental) on Betula nana, as he only observed adults on the plant. However, all stages were present in the populations we found on Betula nana, and they were clearly thriving, albeit under somewhat artificially favourable conditions.
Durak & Wojciechowski (2008) found that the eudominant species (comprising more than 10% in numbers) in Querco roboris-Pinetum mixed coniferous forest were Calaphis betulicola and Betulaphis quadrituberculata. For Calaphis betulicola an average of two peaks of occurrence were observed, one in the middle of May, the other in the middle of June. In the Leucobryo-Pinetum forest association an average of three peaks of Calaphis betulicola were observed – in the middle of May, in the middle of June, and in the middle of September.
Other aphids on same host:Blackman & Eastop list about 72 species of aphids as feeding on birches worldwide, and provides formal identification keys for aphids on Betula. Of those, only 18 species occur on silver birch (Betula pendula) and/or downy birch (Betula pubescens) in Europe.