Aphis folsomii

Identification & Distribution

Adult apterae of Aphis folsomii are dark reddish brown, with dark or dusky siphunculi (see first picture below). Their antennal tubercles are weakly developed. The antennae of apterae are pale, apart from segment VI which is dark. The longest hairs on the third antennal segment are less than 3.5 times the basal diameter of the base of antennal segment III. The apical rostral segment (RIV+V) has 8-10 accessory hairs (cf. Aphis illinoisensis and Aphis fabae, which each have only 2 accessory hairs on RIV+V). Abdominal tergites 1 and 7 always have marginal tubercles. Their legs are dark apart from the apical parts of the tibiae. The cauda is short and broad, about as long as its basal width, with more than 20 hairs (cf. Aphis illinoisensis and Aphis fabae, which each have the cauda much longer than its basal width, with 7-19 hairs). The body length of adult apterae is 1.6-1.8 mm. Immature Aphis folsomii are light reddish brown with pale siphunculi.

Alate Aphis folsomii (see second picture above) are reddish brown with a black head, thorax, antennae and legs and siphunculi (see Boudreaux, 1947). The antennal segments III, IV and V of alatae are all about the same length (cf. Aphis illinoisensis, which has antennal segment III much longer than IV or V).

Aphis folsomii feeds on Parthenocissus species such as Virginia Creeper (Parthenocissus quinquefolia) and Boston Ivy (Parthenocissus tricuspidata). They form dense clusters along the midribs of leaflets and petioles, where they are attended by ants (see third picture above). The ant Crematogaster ashmeadi has been recorded as attending Aphis folsomii on Parthenocissus quinquefolia (Nielsson et al., 1971). Hottes & Frison (1931) reported this aphid species is never abundant enough to be conspicuous, and is not likely to become of economic importance. Davis (1908) has described the sexual as well as the viviparous forms. The Virginia Creeper Aphid is widely distributed in the USA east of the Rocky Mountains.

Other aphids on the same host

Aphis folsomii has been recorded from 3 Parthenocissus species (Parthenocissus inserta, Parthenocissus quinquefolia, Parthenocissus tricuspidata).

Blackman & Eastop list 10 species of aphid as feeding on Parthenocissus 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 especially grateful to Claude Pilon for pictures of Aphis folsomii (for more of her excellent pictures see). 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 Hottes & Frison (1931), 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).

Useful weblinks

References Boudreaux, H.B. (1947). Taxonomic Studies of Louisiana Aphids. LSU Historical Dissertations and Theses. 7904. Full text Davis, J.J. (1908). A new aphid on the Virginia Creeper: (Aphis folsomii n.sp.). Entomological News 19(4), 143-146. Hottes, F.C. & Frison, T.H. (1931). The Plant Lice, or Aphiidae, of Illinois. Illinois Natural History Survey Bulletin 19(3), 123-447. Full text Nielsson, R.J. et al. (1971). A preliminary list of ants associated with aphids in Florida. The Florida Entomologist 54(3), 245-248. Full text