Identification & Distribution:
Aphis chloris (St John's wort aphid, Hypericum aphid) is rather bright green, pale yellow-green or dark green and is a member of Aphis frangula group. It has dark siphunculi but a rather pale cauda. The abdominal dorsum is usually entirely membranous with few if any sclerotized areas. Trochantral hairs are short and all femoral hairs are much shorter than the least tibial width. The body length of Aphis chloris apterae is 1.0-1.8 mm. The alate has dusky marginal and postsiphuncular sclerites and bands across tergites 7-8 or 6-8.
There are taxonomic problems surrounding this aphid. Stroyan (1984) provided a detailed description of Aphis chloris and stated that it lived in ant-attended colonies at stem bases of Hypericum perforatum just below the soil surface or occasionally on aerial parts. But he noted another 'as yet undescribed' species found several times on Hypericum androsaemum and Hypericum calycinum which differed from Aphis chloris in having longer trochantral hairs. Blackman covers the undescribed species as 'Aphis sp. (Stroyan 1984,124)'.
We are awaiting an image of this species...
The St John's Wort aphid does not host alternate. It lives on Hypericum spp. especially St John's Wort (Hypericum perforatum).
- Blackman, R. L. & Eastop, V. (2006). Aphids on the World's Herbaceous Plants and Shrubs. Vols 1 & 2. J. Wiley & Sons, Chichester, UK. Full text
- Hill, D.S. (1987). Agricultural insect pests of temperate regions and their control. CUP, Cambridge.
- Stroyan, H.L.G. (1984). Aphids - Pterocommatinae and Aphidinae (Aphidini). Handbooks for the identification of British insects. 2 (6) Royal Entomological Society of London.