Gardeners have been urged by scientists to help find a mysterious bug which disappears in spring and reappears at the end of summer.
The Royal Horticultural Society (RHS) is asking people to send in sightings of the giant willow aphid (Tuberolachnus salignus) so that they can find out where it goes and how it interacts with garden plants.
At close to 6mm long with a distinctive shark-like fin, it is one of the UK’s largest aphid species, and an RHS team of entomologists is asking gardeners to send pictures if they see it. The team wants to work out why the “mysterious” and “intriguing” garden bug has its fin, and discover more about its lifecycle as well as which plants may host it.
Giant willow aphids are regularly seen from July to February, with a peak in sightings in autumn. As the name may suggest, they are found on willow in particular, but the RHS wants to know if they are found on other plants, and especially if they are seen between February and the end of May.
The insects are easy to see with the naked eye but sometimes retreat into crevices in bark to hide from predators. They are usually seen on the stems and branches of trees, and do not cause unsightly damage to host plants, which can withstand the delicate feeding from these insects.
In May 2022, colonies were found on a quince tree (Cydonia oblonga) in Hertfordshire, a new host for this aphid. They had previously mainly been found on willow and occasionally on other trees including apple and poplar. Dr Andrew Salisbury, RHS principal entomologist, said: “The sighting of giant willow aphids on quince, a previously unrecorded host, at a time of year when they are rarely seen, only raises more questions about this fascinating and sometimes elusive aphid.
“Despite thorough research, it isn’t certain where they go from April to June, and their host range needs more investigation. We are asking gardeners for their help tracking this aphid down to help answer these intriguing questions about this unusual species.”
Gardeners are being used more than ever in science experiments as an untapped resource. Private garden space in Britain covers about 728,900 hectares (1.8 million acres) so their potential as a haven for wildlife is considerable. The RHS’s chief ecologist, Gemma Golding, recently asked gardeners to send pictures of interesting “weeds” in the hope that rare wild plants are discovered growing in new places.
The RHS has also taken more of an interest in wildlife-friendly gardening in recent years, with painstakingly maintained and sterile gardens becoming a thing of the past.
The RHS, which runs Chelsea Flower Show, has changed its attitude to previously unwanted visitors to the garden, last year announcing it would no longer class slugs and snails as pests. Britain’s leading garden charity said that although the gastropods were the garden visitor about which they received most complaints, they should be considered an important part of the garden ecosystem. At RHS flower shows, you are now just as likely to receive tips for how to entice nature into your garden as you are to see perfectly pruned roses.
Sightings of the giant willow aphid, which must include a picture, can be submitted to the RHS here.
