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Aphididae : Aphidinae : Macrosiphini : Corylobium


Genus Corylobium

Hazel aphids

On this page: Corylobium avellanae

Genus Corylobium [Macrosiphini]

Corylobium are green, sometimes reddish, medium sized spindle-shaped aphids, the adult viviparae of which may be winged or wingless. The antennae are longer than the body. The median and antennal tubercles are well developed, and the inner margins of the antennal tubercles diverge. The body has numerous capitate hairs arising from tubercles on the body. The siphunculi are long and thin and the cauda is very short and triangular.

There is only 1 species in the Corylobium genus, which lives on hazel (Corylaceae). It is widely distributed in Europe and has been introduced to North America. It retains a sexual stage in its life cycle, and is not attended by ants.


Corylobium avellanae (Large hazel aphid)

Corylobium avellanae apterae are usually yellowish-green (see first picture below) but in one form the aphid is mottled with red (see second picture below). The antennae are pale with dark tips to the segments and black apices. The dorsum is granulate with numerous small cuticular structures (best seen in picture in alcohol below) and 6-8 low conical tubercles per segment, each with one or two long thick capitate hairs. The siphunculi are long, thin and tapering, 4.2-5.5 times the length of the cauda. The body length of Corylobium avellanae apterae is 1.7-2.9 mm.

The alate (see first picture below) has the head and thorax brown, and the abdomen green or dirty red, with marginal sclerites, and intersegmental pleural sclerites or crossbars. The dorsum is not granulate. The body hairs are short and thin and not capitate. The siphunculi of the alate are 0.27-0.32 times the body length.

The large hazel aphid does not host alternate but spends its entire life cycle on hazel (Corylus avellana). Sexual forms occur in autumn and overwintering eggs are laid on hazel. It mainly feeds on the fast growing shoots and only rarely on the leaves, which are utilized by another species - Myzocallis coryli. Corylobium avellanae is distributed over most of Europe east to Ukraine and Russia and west Asia. It has recently been found in Canada.



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


  •  Heie, O.E. (1980-1995). The Aphidoidea, Hemiptera, of Fennoscandia and Denmark. (Fauna Entomologica Scandinavica) E.J. Brill, London