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Genus Anoecia

Dogwood - grass aphids

On this page: Genus Anoecia Anoecia corni

Genus Anoecia [Anoeciinae]

Anoecia are medium-sized aphids which may be winged or wingless. Wingless adults are greenish-gray or gray with a dark sclerotic dorsal abdominal plate. The winged form has a characteristic dark posteriodorsal abdominal patch and a large black pterostigmal spot on the forewing. Young nymphs are white or cream in colour.

There are about 24 Anoecia species in North America, Europe and eastern Asia. Some host alternate from dogwood (Cornaceae) to roots of grasses (Poaceae), with the oviparae laying their eggs on the bark of the trunk. Other Anoecia species live year-round on the roots of grasses (Poaceae) or sedges (Cyperaceae).

 

Anoecia corni (Common dogwood-grass aphid)

Anoecia corni apterous fundatrices in spring on dogwood (Cornus) are dark brown or blackish (see first picture below). They have reduced eyes and 5-segmented antennae, whereas subsequent generations have large compound eyes and 6-segmented antennae. The siphunculi of all Anoecia corni forms are reduced to inconspicuous pores. Winged forms, both spring migrants and the sexuparae returning to Cornus in autumn (see second picture below), have a large black pterostigmal spot on the forewing, and a white band bordering the dark patch on abdominal tergites III-VI (cf. Anoecia vagans which has no dark dorsal abdominal patch).

It is difficult to separate the apterae of Anoecia corni from two other Anoecia species that (may) occur on dogwood, but the alates may be distinguished by examining their antennae. The 5th and 6th antennal segments of Anoecia corni alates both have secondary rhinaria (c.f. Anoecia vagans which has none on those segments). The third antennal segment of Anoecia corni has 9-17 secondary rhinaria (c.f. Anoecia major which has 13-22 secondary rhinaria on that segment). The body length of winged forms is quite variable, ranging from 1.9-3.0 mm. The third picture above shows a colony of Anoecia corni on its secondary host - roots of grasses, attended by the common black ant Lasius niger.

In Europe Anoecia corni host alternates between dogwood (Cornus spp.) and roots of grasses (Poaceae). In eastern Asia and in areas where introduced (South Africa and North America), the dogwood-grass aphid remains all year round on grasses and some cereals. The species is found throughout Europe, and in Asia, Africa, and North and South America.

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Acknowledgements

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).

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