It’s the world’s largest aphid, fiercely guarded by ants and milked like a dairy cow. Now the Giant oak aphid needs your help. The new survey will help us to map where it lives so that we can discover just how rare it really is.
There are almost six hundred species of aphids in Britain. Most of them are harmless to gardeners, and many are extremely rare. The Giant oak aphid (Stomaphis quercus) is one such aphid. It is the world’s largest aphid – about the size of a coffee bean – and it feeds solely on the trunk of the English oak tree.
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| Jet black ants protect the Giant aphid from predators in return for honeydew (c) Dr Bernhard Seifert |
The Giant oak aphid also has its very own bodyguard, the Jet black ant (Lasius fuliginosus), and is never found without it. The ants guard the aphids fiercely in return for drops of honeydew – they literally milk the aphids as protection money! They even take the aphids down into their nest in the winter. It is said that the ants carry the aphids high up the tree in spring and to the base of trunk in autumn, rather like Alpine shepherds with their flocks of sheep.
Why do they need our help?
The Giant oak aphid lives in a fascinating mini-world, but like many bugs (also known as invertebrates) it’s very rare and therefore in danger of disappearing altogether. Bugs are critically important to the planet, and without them life on earth would collapse. At least 65% of all species are bugs, providing us with food and ecological, agricultural, medical and technological benefits. Bugs are essential food to birds and mammals, they pollinate our crops and they help to purify our water.
How to take part in the Giant Aphid hunt
The best time to see the Giant oak aphid is in August and September. Visit oak woodland and take a close look at trees at the edge of woodland or that stand alone (the aphid doesn’t like the shade). The aphid is only known from fives sites in the UK, with a stronghold in the east of England, particularly the Norfolk Brecks. The aphid has also been found near Colchester and Exeter, and may occur in other areas.
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| The Giant aphid can be found on unshaded oak trees (c) Graham Thacker |
How to identify: The Giant oak aphid is pear-shaped, with an obvious bronze colour. Normally the first evidence of it, and visible from several metres away, are clusters of the Jet black ant gathered around individual aphids. The ants are, as the name suggests, jet black and shine as if polished or painted with gloss paint: if you are unsure, you probably don’t have the right ant. Once the ants have been spotted, closer inspection is required to confirm the presence of the aphid, which is unmistakeable.
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| Clusters of Jet black ants reveal the presence of the Giant aphid (c) Graham Thacker |
It is important to record as many features of the site as possible; if at all possible, photograph the aphid (even a poor photograph at distance would help us to confirm it). Negative records from apparently suitable habitats – i.e. with Jet black ant and English oak – are also important.
Submit your records to hopkins@fireflyuk.net or call 01603 660300.
This project is supported by The British Entomological and Natural History Society.
