By John W Meiklejohn & Harry Green
There has been a national wasp survey this year so we have been peering at wasp faces down a microscope to identify the species (if you want to try wasp identification see excellent key by George Else 1994). Practically every wasp we looked at was Common wasp Vespula vulgaris and we have heard reports of many nests in holes in the ground. Interestingly Geoff Trevis found a wasps nest suspended in a bush and after it was inactive he sent it off to national expert, Dr Mike Archer, who confirmed that it was of the Median of French Wasp Dolichovespula media. This European species was first recorded in Britain in 1980 with the first nest in 1985, both in Sussex. Since then it has considerably extended its range with a few records in Worcestershire (JM). This species has a bad reputation because its big, supposedly French, and, allegedly, a vigorous attacker of humans! This is probably because it suspends its nest in bushes which people inadvertently cut, shake or bash, so naturally the wasps try to see-off a possible predator! In the early stages their paper nests have a typical tapering bottle-neck -shaped entrance.
Coincidentally I was trimming a small laburnum tree in our garden in September and noticed to my astonishment (we walk under the tree every day!) a wasps nest suspended from a branch about 10 ft up. The nest appeared to have failed as it was inactive , and there were many unused cells - perhaps the queen had died. It was about 14 cms diam and 17 cm high, and from its shape I hoped it was D. media. I sent photos to Tom Ings (organiser of the wasp survey) who wrote:
"I think you are right that it is a nest of D media, it looks like the few I have seen. The early stages are much easier to identify as they have a long narrow opening rather like a bottle neck which disappears as the nest develops. As far as I can tell from the photos the nest had not reached maturity and produced new queens or males as there appears to be only small cells and three combs. I can only assume that the queen died before the nest was fully developed as there are no larvae etc, then the workers must have carried on without the queen until all had emerged".
In the hope of confirmation Geoff Trevis sent the photos to hymenopterist Dr Michael Archer who confirmed that the nest was of a species of Dolichovespula, and told us to measure the width of the largest cells across the flats of the hexagon: D media would measure 8 mm, other species 6-6.5mm. I had retained the nest and the largest cells measured 6.1 mm!. However, as the nest had not reached maturity, perhaps larger cells had not been produced. On comparison with descriptions and pictures in Spradbury (1973) I concluded that the nest was probably of Norwegian Wasp D. norwegica, or possibly Tree Wasp D sylvestris but might just maybe D media!
I (GHG) visited the South Birmingham Group of Worcestershire Wildlife Trust on 13th October 2000 to give a talk.. In the break Malcolm Beach showed me a small branch of Lawsons Cypress x leylandii "Castle Welland" with several small masses of tiny chambers about 1 cm diameter stuck to the twigs. He had found them in a garden at Hawkesley, near Kings Heath, grid ref about SP049773, in early October. Apart from a guess that they might be made by a hymenopteran I did not know what they were so I took some home and showed them to JWM. He didnt know what they were either so he sent one to Michael Chinery (of insect Field Guide fame), who replied as follows:
"You are quite right about it being a clump of hymenopteran cocoons or pupation chambers. It belongs to some kind of braconid. I can't say which species, but Gauld & Bolton (1988) mention Diolcogaster as one of the genera that produce honeycomb-like stacks of cocoons. The parasites may well have come from a small looper caterpillar - they often spin up under the arched body of the victim and this gives the cluster its neat shape. There is a very nice photograph of such a cluster in Step's Bees, Wasps, Ants and Allied Insects - one of the old Wayside and Woodland series.
The only looper that I know of that feeds on Lawson's cypress is the Cypress Pug Eupithecia phoeniceata. This relative newcomer to Britain is spreading northwards with the increasing use of cypress hedges, although I don't know that it eats the abominable leylandii. The caterpillars feed in the autunm and winter, so this fits quite well if you have only recently found the cocoons".
Skinner 1998 states that the first British specimen of Cypress Pug was found in Cornwall in 1959 and has since spread through the southern counties and has been recorded as far north as Rugby, Warwickshire. The larvae will apparently eat Cupressocyparis x leylandii in captivity! We had not yet checked current status in Worcestershire and West Midlands.
Braconidae are small, active, inconspicuous insects, and the great majority are parasitoids on other insects. They are abundant worldwide and there are about 1045 species in 138 genera in Britain (Gauld & Bolton 1996).
|Mass of Braconid cocoons (possibly genus Diolcogaster)
on Lawson's Cypress. Actual size of mass 10 x 8 mm and 3
mm thick. Problably formed inside the curve of a looper
moth caterpillar - likely species Cypress Pug Eupitheicia
phoeniceata according to Michael Chinery (in lit).
Part of wasp's nest, probably Dolichovespula norwegica, possibly sylvestris from top of laburnum tree 3 m above ground. Cell width across the flats of the largest cells is 6.1 mm.
Many thanks to Geoff Trevis, Michael Archer Tom Ings and Michael Chinery for helping us with our enquiries. Also to Malcolm Beach for the Braconid cell cluster.
|ELSE, G 1994 Identification - Social wasps. British Wildlife Vol 5, 304-311.|
|GAULD I. & BOLTON, B. first impression 1988, reprinted 1996. The Hymenoptera. The Natural History Museum, London and OUP.|
|SKINNER, B. 1998 (2nd ed) Colour identification guide to the moths of the British Isles. Viking.|
|SPRADBURY, JP. 1973. Wasps. Sidgwick & Jackson.|
|STEP. E. 1946 Bees, wasps, ants and allied insects of the British Isles. Frederick Warne.|
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