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Aphidinae : Macrosiphini : Eomacrosiphon nigromaculosum
 

 

Eomacrosiphon nigromaculosum

Black-and-red rose aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

Adult apterae of Eomacrosiphon nigromaculosum (see first picture below) are bright red with black bands or black patches on the dorsal abdomen; the body is truncate posteriorly, and the black siphunculi are held erect. (The fundatrix of this species, see second picture below, differs from apterae in later generations in having shorter antennae and shorter thicker siphunculi.) Antennal segments are pale except for the apices of segments V and VI which are dark. There are no secondary rhinaria on the antennae of the aptera (cf. Macrosiphum rosae, which do have secondary rhinaria on the antennae of the aptera). The rostrum reaches the second pair of coxae. The legs are pale brownish yellow, except for the tips of the femora and tibiae, and all the tarsi which are dark. The first tarsal joints have 5 hairs. There are rather long hairs on the hind tibia. Marginal tubercles are very conspicuous, and present on the pronotum and more or less regularly on each of abdominal tergites I to VII. The siphunculi are unusually thick, very densely and heavily imbricated, with very small hexagonal cells in the reticulated area. The siphunculi are completely black (cf. Ericaphis fimbriata, Ericaphis scammelli and Metopolophium dirhodum, which have partially or wholly pale siphunculi). The cauda is rather slender, and bears 4-5 pairs of lateral hairs. The body length of adult Eomacrosiphon nigromaculosum apterae is 2.0-2.8 mm.

Images above copyright Andrew Jensen, under a creative commons licence.

The alate Eomacrosiphon nigromaculosum (not pictured) has the head and thorax black, and the abdomen red, with a black band across tergites V and VI, and broken white intersegmental lines between all tergites. The antennae have segments I and II blackish, and the remainder dusky. The cauda and legs, except the tips of the segments, are yellow. The tarsi, tips of tibiae and siphunculi are black. The fore wing is dusky at the tip between the radial sector and media.

Eomacrosiphon nigromaculosum is found on various wild and cultivated rose (Rosa) species in western North America. These aphids cluster in masses along the stems, seldom spreading to the buds or leaves. Most accounts assume the species is monoecious, and remain on rose all year, but Jensen reports finding 'nascent' colonies of Eomacrosiphon nigromaculosum on an unrelated host - mountain tobacco (Arnica). Whether this is a true summer host, or merely an accidental host utilized during the dispersive phase, is as yet unclear. Eomacrosiphon nigromaculosum is holocyclic, with alate males. The black-and-red rose aphid is restricted to western USA and Canada.

 

Other aphids on the same host

Eomacrosiphon nigromaculosum has been recorded on 2 species of wild rose (Rosa fendleri, Rosa nutkana) and on various cultivated varieties.

Acknowledgements

We are grateful to Andrew Jensen for making his pictures of Eomacrosiphon nigromaculosum available for use under a creative commons licence.

Identifications were made by the copyright holder of the pictures. We have used the keys and species accounts of MacDougall (1926) & Palmer (1952) (both as Macrosiphum nigromaculosum) along with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections 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

References

  • MacDougall, A.P. (1926). Some new species of Macrosiphum from British Columbia (Homoptera: Aphididae). The Pan-Pacific Entomologist 11(4), 165-173. Full text

  • Palmer, M.A. (1952). Aphids of the Rocky Mountain Region: including primarily Colorado and Utah, but also bordering area composed of southern Wyoming, southeastern Idaho and northern New Mexico. Thomas Say Foundation, Denver. Full text