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Aphididae : Calaphidinae : Calaphidini : Clethrobius


Genus Clethrobius

Hairy birch aphids

On this page: Clethrobius comes

Genus Clethrobius [Calaphidini]

Clethrobius are a genus of large hairy elongate brown aphids. All adult viviparae and males are winged; the ovipara is wingless. The antennae are shorter than the body. The abdominal dorsum has pigmentation confined to marginal sclerites plus a few bands. There are also bands of light wax pulverulence on the abdomen. The siphunculi are short and truncate, and the cauda is knobbed.

This genus comprises three or four Palaearctic species living on twigs and young branches of Alder (Alnus) and Birch (Betula) species. They have a sexual stage in their life cycle, but do not host alternate. Clethrobius aphids may be attended by ants


Clethrobius comes (Brown hairy birch aphid)

All adult viviparous female Clethrobius comes are winged. Freshly moulted viviparae of Clethrobius comes (see first picture below) are light brown, but matured adult alatae (see second picture below) are dark brown or greenish black. The scleroites as far back as tergite VI bear groups of wax pore facets, producing bands of light wax pulverulence (see second picture below). The marginal sclerites on tergites I-IV are produced into blunt rounded prominences bearing 2-3 marginal hairs each. The antennae, legs and cauda are black, apart from the bases of the femurs which are pale. The antennae are much shorter than the body, with a terminal process that is 0.67-0.75 times the length of the base of the last antennal segment. The rostrum is very short, hardly or just reaching the middle coxae. The siphunculi are dark sclerotic, shortly conical, in length about 0.6 times their basal width. The cauda is knobbed and distinctly constricted. The body length of winged Clethrobius comes viviparae is 4.1-4.4 mm.

The hairy birch aphid forms clusters on branches and twigs of birch (Betula spp.), often where the new growth is dying back, or on twigs of alder (Alnus spp.) overhanging streams. The populations on alder are regarded by some as a separate species, Clethrobius giganteus, and attempts to transfer aphids from birch to alder have not succeeded. However, no consistent morphological differences have been found. Sexual forms develop in October-November. Clethrobius comes occurs throughout Europe and across Asia to China, Korea and Japan.



Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994) and Blackman & Eastop (2006) supplemented with Blackman (1974), Stroyan (1977), Stroyan (1984), Blackman & Eastop (1984), Heie (1980-1995), Dixon & Thieme (2007) and Blackman (2010). We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks


  • Dixon, A.F.G. & Thieme, T. (2007). Aphids on deciduous trees. Naturalist's Handbooks 29. Richmond

  • Stroyan, H.L.G. (1977). Homoptera: Aphidoidea (Part) - Chaitophoridae and Callaphidae. Handbooks for the identification of British insects. 2 (4a) Royal Entomological Society of London. Full text