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Bronze-brown dandelion aphidIdentification & Distribution Biology & Ecology Other aphids on Common Dandelion
Identification & Distribution:Adult apterae of Uroleucon taraxaci are shining dark bronze-brown. The antennae and legs (except for the femoral bases) are black. Dorsal abdominal hairs are mostly placed on dark scleroites, which are black and numerous and sometimes merged together. Antesiphuncular and post-siphuncular sclerites are either absent or very small. The rather short and thick cauda is black like the siphunculi, and bears 8-12 hairs. The body length of the adult Uroleucon taraxaci aptera is 2.5-3.8 mm.
The bronze-brown dandelion aphid is seldom seen as, unlike most members of the genus, it is light-averse. It lives on leaf undersides and basal leaf parts of of dandelion (Taraxacum spp.) near ground level. Uroleucon taraxaci is found in Britain, throughout continental Europe, parts of Asia, and has been introduced to North America.
Biology & Ecology:
Uroleucon taraxaci is strongly photophobic. The two colonies we have found were located on the basal parts of the leaves of dandelions (Taraxacum officinale) growing in shaded situations. One of those colonies is shown below.
The youngest immatures are usually spaced out along the youngest leaves of the dandelion (as below).
The cauda of the fourth instar is short and triangular, but the adult (see picture below) has a short finger-like cauda.
The often partly-concealed location of the colony makes accumulation of honeydew droplets a potential problem because of bacterial growth. Some aphids flick honeydew away with their cauda (Blackman, 1974 ), but this would probably not be possible with such a short cauda. The problem is solved for many aphids by ant attendance, but Uroleucon aphids are not usually attended by ants (but see Tido (2002) below). The bronze-brown dandelion aphid sometimes uses an alternative method to prevent accumulation of honeydew - it kicks the droplets away with its back legs. The aphid shown below has just kicked a droplet outside the frame of this picture.
van Emden (2013) notes that many aphid species "kick honeydew droplets that form at the anus away from themselves to land elsewhere on the plant or fall to the ground." Tido (2002) found a very large colony on the undersides of leaves and leaf bases of dandelion. Unlike the colony we found (and unusually for Uroleucon), it was attended by ants.
There is nothing in the literature about natural enemies of Uroleucon taraxaci, but the colony we observed (in captivity) was eventually eliminated by Aphidoletes larvae that hatched from eggs deposited prior to our finding this aphid colony. The first image below shows a yellowish Aphidoletes larva moving in for the kill, and the second shows the aphid nymph being held in the air by the midge larva shortly thereafter.
Other aphids on Common Dandelion (Taraxacum officinale):
Blackman & Eastop list 37 species of aphid as feeding on Taraxacum officinale worldwide, and provide formal identification keys. Of those aphid species, Baker (2015) lists 25 as occurring in Britain: Aphis craccivora Aphis fabae Aphis gossypii Aphis spiraecola, Aphis taraxacicola Aulacorthum solani Brachycaudus cardui Brachycaudus helichrysi Brachycaudus lateralis Hyperomyzus lactucae Hyperomyzus pallidus Macrosiphum euphorbiae Myzus ascalonicus Myzus cymbalariae, Myzus ornatus Myzus persicae Neomyzus circumflexus Pemphigus bursarius Trama caudata, Trama rara, Trama troglodytes Uroleucon cichorii, Uroleucon grossum Uroleucon sonchi and Uroleucon taraxaci.
Bell et al. (2015) (Appendix S2) have also published an "annotated checklist of aphids present in the UK". We discuss some of the reasons for the differences between Baker's and Bell's lists in our rare aphids page.