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Macrosiphoniella sejuncta

Large mottled yarrow aphid

On this page: Identification & Distribution 

Identification & Distribution:

Adult Macrosiphoniella sejuncta apterae are usually green mottled with brownish red, with no wax powdering (see two pictures below). The antennae are rather dark with a paler base to segment III. Macrosiphoniella sejuncta siphunculi are greenish brown to brown with paler bases and the cauda is a pale greenish brown. The body length of the adult aptera is 2.5-3.1 mm.

The first tarsal segment has only 3 hairs. Their siphunculi are very thin, slightly swollen at the base, slightly widened at the apex and with reticulation on the apical 48-69%. The siphunculi are 1.7 to 2.2 times the length of the cauda. The picture below left shows the pale cauda in profile along with some red nymphs of another species, Uroleucon achilleae

The aptera has dark crescent shaped presiphuncular sclerites (see second micrograph above of an aptera in alcohol, and first below of a clarified slide mount ).

Micrographs of clarified mounts  by permission of Roger Blackman copyright AWP  all rights reserved.

The alate is much like the apterous viviparous female, but is more slender and has well developed marginal sclerites as well as presiphuncular sclerites (see micrograph of clarified slide mount above right). The third antennal segment has 30-40 rhinaria. The ovipara is similar to the apterous vivipara, but the cauda is slightly thicker and blunt, and the basal half of the hind tibia is swollen (see first micrograph of clarified slide mount below).

Micrographs of clarified mounts  by permission of Roger Blackman copyright AWP  all rights reserved.

The male is wingless and small with a body length of only about 2 mm (see second micrograph above).

Macrosiphoniella sejuncta feeds on the older leaves close to the ground of yarrow (Achillea millefolium). The best way to find these aphids is to shake the host-plants over a sheet placed on the soil under the leaves. The species does not host alternate, but remains all year on yarrow - overwintering in the egg stage. Sexual forms can be found in September and October. The large mottled yarrow aphid is found across Europe east to Western Siberia.

Acknowledgements

Our particular thanks to Roger Blackman for images of his clarified slide mounts.

We also thank Middle Farm, East Sussex  for their kind assistance, and permission to sample.

We have made provisional 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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