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Comfrey aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Aphis symphyti (see two pictures below) are dark green to pale yellowish green, more rarely lemon yellow. They are not covered in wax. Their antennae are 6-segmented with the terminal process 1.7-3.0 times as long as the base of antennal segment VI. The apical rostral segment (RIV+V) is 0.12-0.16 mm in length (cf. Aphis gossypii, which has RIV+V 0.075-0.135 mm long). The apterae have no dark markings anterior to the siphunculi, but may or may not have bands across tergites VII-VIII (cf. Aphis fabae, which usually has some dark markings anterior to the siphunculi, and always has well developed dark cross bands on tergites VII & VIII). There are marginal tubercles on tergites I and VII which are very variable in size. The femoral hairs are similarly variable in length, and may be less than or more than the least width of the hind tibiae. The siphunculi are uniformly dark, and are 1.2-1.7 times the length of the cauda. The cauda, which bears 5-8 hairs, is usually dusky, but in spring is sometimes black. The body length of adult Aphis symphyti apterae is 1.3-2.0 mm.
Note: This is one of the 'small frangulae' species much referred-to by Stroyan (a group of perhaps 10 species closely resembling Aphis frangulae, including Aphis lamiorum, Aphis parietariae, Aphis praeterita, Aphis ruborum, Aphis urticata). Aphis symphyti is difficult to distinguish from other members of this group on morphological grounds but, in most cases, differs in host. There are however some generalists in the group, most importantly Aphis gossypii, which is thought to occur on various genera in the Boraginaceae. Working solely from these photographs we cannot therefore be 100% certain of the identity of the aphids pictured here - given the host they are most likely Aphis symphyti, but could be Aphis gossypii.
Both images above, by permission copyright Dirk Baert, all rights reserved.
Alatae have secondary rhinaria distributed 8-12 on antennal segment III, 1-4 on segment IV and 0-2 on segment V. They have well developed marginal and postsiphuncular sclerites, bands across tergites VII & VII, a short bar on tergite VI and variably developed bands on tergites I-V (which may be absent).
Both images above, by permission copyright Marko Šćiban, all rights reserved.
Aphis symphyti has been recorded from several members of the Boraginaceae (the borage or forget-me-not family), although some of these may be misidentifications of Aphis gossypii. Aphis symphyti lives scattered under the leaves of comfrey (Symphytum officinale), the only host upon which it is known to reproduce sexually. As numbers increase, their colonies spread up the stems and on to the flower head (see pictures above). Dense colonies may be attended by ants. Sexuales develop in autumn, and eggs are deposited on comfrey. Aphis symphyti is found over most of Europe apart from Scandinavia and the Iberian peninsula.
Other aphids on the same host
Aphis symphyti has been recorded from 2 species of Symphytum (Symphytum officinale, Symphytum ottomanum).
Aphis symphyti has been recorded from 2 species of Anchusa (Anchusa azurea, Anchusa officinalis).