Myzodium modestum (Dark brown moss aphid) identification, images, ecology, control

Adult apterae of Myzodium modestum (see two pictures below) are reddish brown to dark brown or olive, sometimes greenish posteriorly, with black siphunculi. The cuticle is sclerotic and wrinkled. Antennal tubercles are moderately produced and divergent, and are covered by small blunt scales or nodules (cf. Pseudacaudella rubida, which has the antennal tubercles undeveloped and the cuticle of the head almost smooth dorsally). The antennae are 0.6-0.7 times the body length, with a pointed terminal process, 2.4-2.5 times as long as the base of antennal segment VI. Antennal segments I and II are almost as rough as the head. The rostrum reaches to the hind coxae, with the apical rostral segment 1.7-1.8 times the second hind tarsal segment. Marginal tubercles are absent. The siphunculi are 3-4 times the cauda, slightly S-curved, somewhat flattened in the middle, and with a constriction just below the very large flange (cf. Muscaphis escherichi & Muscaphis cuspidata, which have no subapical constriction of the siphunculi). The cauda has a broad basal part, and a rather narrow distal part, and is almost totally covered by abdominal tergite VIII. The body length of adult Myzodium modestum apterae is 1.2-1.9 mm.

Myzodium modestum (dark brown moss aphid) aptera; Anders Albrecht

Images above copyright Anders Albrecht, under a Creative Commons Attribution 3.0 License.

Myzodium modestum alatae (see picture below) have a large dark dorsal abdominal patch. Secondary rhinaria are distributed 21-45 on antennal segment III, 7-13 on segment IV, and 0-4 on segment V.

Myzodium modestum (dark brown moss aphid) preserved alate; CBG group

Image above copyright CBG Photography Group under a Creative Commons Attribution 3.0 License.

Myzodium modestum has been found on various mosses, such as Catharinaea and Polytrichum (Polytrichaceae), Pohlia (Bryaceae), Rhacomitrium (Grimmiaceae) and Sphagnum (Sphagnaceae). In America Smith & Robinson (1975) reported Polytrichum commune as the most common host for this aphid. Until recently populations were assumed to be anholocyclic, but Pérez Hidalgo et al. (2017) found oviparae and alate males on moss at high altitude in Switzerland in mid-September, indicating at least some populations may be monoecious holocyclic. Another moss aphid in the same genus, Myzodium mimulicola has been found to host alternate, with black hawthorn (Crataegus douglasii) as the primary host. Myzodium modestum is not attended by ants. It is found in Europe, especially northern Europe, and in North America.

Other aphids on the same host

Myzodium modestum has been recorded on 3 species of mosses in the Polytrichum genus (Polytrichum commune, Polytrichum juniperinum, Polytrichum strictum).

Blackman & Eastop list 5 species of aphid as feeding on common haircap moss (Polytrichum commune worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 5 as occurring in Britain (Show British list).

Myzodium modestum has been recorded on 1 species of moss in the Atrichum genus (Atrichum undulata).

Blackman & Eastop list 3 species of aphid as feeding on Atrichum undulata worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 3 as occurring in Britain (Show British list).

Acknowledgements

We are grateful to Anders Albrecht and CBG group for making their images of Myzodium modestum available for use under a creative commons licence.
We have used the species accounts of Smith & Robinson (1975) and Heie (1992) together with information from Albrecht (2015) and 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 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

Heie, Ole E. (1992). The Aphidoidea (Hemiptera) of Fennoscandia and Denmark. IV. Family Aphididae: Part I of tribe Macrosiphini and subfamily Aphidinae. Fauna Entomologica Scandinavica 25, 1-189. (p. 173).
Smith, C.F. & Robinson, A.G. (1975). The genus Myzodium with the description of M. knowltoni, new species (Homoptera: Aphididae). Proceedings of the Entomological Society of Washington 77, 481-486. Full text

Myzodium modestum

Dark brown moss aphid

Identification & Distribution

Other aphids on the same host

Acknowledgements

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References