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Hornbeam aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host
Identification & Distribution:
Immature Myzocallis carpini (see first picture below) are unmarked, and have the body hairs (and a few basal antennal hairs) capitate, and very much longer than those of the adult. Winged adult Myzocallis carpini viviparae (see second picture below) are pale yellow to yellowish white, with no dorsal abdominal markings. The forewing has a black spot at the base of the pterostigma. Their antennae are ringed with black, and antennal segment VI is 4.4 to 5.3 times as long as the apical rostral segment. The apical rostral segment is at most 1.02 times as long as the second hind tarsal segment. The body length of alate Myzocallis carpini is 1.3-2.2 mm.
The hornbeam aphid is found on the undersides of leaves of hornbeam (Carpinus betulus), especially when used for hedging. Myzocallis carpini is found in Europe, North Africa, the Middle East, and has been introduced into New Zealand and North America.
Biology & Ecology
Stroyan (1977) considered Myzocallis carpini widespread in Britain, but not very common. We have found it in Sussex more or less wherever the host is found, but it seldom reaches the same densities of some other Myzocallis species such as Myzocallis coryli.
The nymphs are generally not aggregated in colonies, but are scattered over the leaves besides the veins, probably reflecting the original larviposition sites of the adult aphid. Note the prominent capitate hairs on the nymphs pictured above.
Large colonies of Myzocallis carpini on the ends of shoots on the undersides of the leaves of hornbeam have been reported by Budgeon (1979) in New Zealand, where Myzocallis carpini is regarded as invasive. She also reported the occurrence of apparent intermediates - namely individuals with the wing bud and antennal characteristics of 4th instar nymphs , but containing well developed embryos with pigmented eyes. We suspect these are just normal fourth instar alatiform nymphs, which will moult to give adult alates.
Reports of natural enemies attacking Myzocallis carpini are few and far between. McEwen et al. (2007) (quoting Szentkiralyi, pers. comm.) believed that larvae of the predatory chrysopids Hemerobius micans and Hemerobius humulinus preyed on this species. Populations of Myzocallis carpini were said to be high in spring (April to May) and autumn (September to November).
Barta (2009) reported the first incidence of a fungal pathogen Entomophthora planchoniana attacking Myzocallis carpini, as well as other Myzocallis species such as Myzocallis castanicola and Myzocallis walshii. The parasitoid Trioxys pallidus has been recorded from it by Tomanovic & Kavallieratos (2002).
Other aphids on same host:
Myzocallis carpini has been recorded from 3 Carpinus species (Carpinus betulus, Carpinus caucasica, Carpinus orientalis).
Blackman & Eastop list one species of aphid as feeding on hornbeam (Carpinus betulus) worldwide: Myzocallis carpini.