Worcestershire Record No. 21 April 2007 p. 40

Brett Westwood

Had you approached more closely you might have heard curious mutterings followed by exclamations of delight filtering through the damp conifer woodland. This was the scene of the rediscovery in Worcestershire of Formicoxenus nitidulus, the Shining Guest Ant by the Wyre Forest Study Group. Harry Green and I had long suspected that this tiny delicate ant, which lives within the nests of Formica rufa, the Wood Ant, was lurking in the vice-county, and we’d been spurred on by features in British Wildlife in which the author had found the ant in Herefordshire and south-east England. Surely it had to be somewhere between?

In October 2005 we searched at Hawksbatch in Wyre Forest, following a tip-off that the male ants spent more time on the surface of the wood ant mounds in late summer and autumn. But we had no success, partly because we hadn’t expected the ants to be so small (they are 2.8-3.0 mms long). In September 2006, with the lynx-eyed support of members of the Wyre Forest Study Group, there was nowhere for the ant to hide, though I think we were all surprised at the diminutive size of the males, dwarfed by lumbering wood ants ten times their size. With their very shiny thoraxes and abdomens, once you’ve got their “jizz”, the ants do stand out well in sunlight as the beams catch their reflective cuticles.

After the initial finding near Hawksbatch, further surveys by Harry Green, Rosemary Winnall and me have revealed Formicoxenus nitidulus in several areas of the Forest, especially along Dowles Brook and in Ribbesford Wood, and it seems likely that it is worth looking for wherever the host Formic rufa is found.

Just what Formicoxenus does within the Formica nests is not known, though its own nests are constructed within hollow sticks, and bracken stalks within the wood ant mound. It seems to be tolerated by its hosts and appears to do them no harm.

Current status
Formicoxenus nitidulus is a UK Biodiversity Action Plan priority species and a species action plan has been produced to guide its conservation. The plan aims maintain its present distribution by ensuring that suitable habitat is not lost. Similar plans apply to the Wood Ants. It is classified as “local” in Britain and Vulnerable in the IUCN Red List.

Harry Green

Our interest in this ant was stimulated by the account given by Baldock 2002 in British Wildlife. In fact it was Brett Westwood who first became intrigued by the species and set us looking for it. David Baldock’s article indicated that the best way to find the species was to sit and stare at wood ant nest piles between September and November! Within a few minutes the flightless males, if present, can usually be seen on the surface of the nest – by which time the observer can be fairly well over-run by wood ants and begins to smell of formic acid! Since we first found them on 16th September we now have records from eleven wood ant nests in several parts of Wyre Forest and Ribbesford Woods and we shall be searching further in 2007. Initial findings suggest they are most easily found on wood ant nests situated in dry sunny places rather than in shade.

Part 4 of the Provisional Atlas of Aculeate Hymenoptera (Edwards 2002) shows about 50 10x10km squares where the Guest Ant has been recorded. Most records (especially the modern ones) are in SE England with other thinly scattered all over England and Scotland. It is suspected that wherever there are wood ants there are likely to be Guest Ants. Formica rufa, F aquilonia and F lugubris are all known as hosts but only the first occurs in Worcestershire. The only record for West Midlands in the Atlas is from before 1900 (There is also a record of similar age from Warwickshire). We have been told that the Worcestershire record was extracted from the Victoria County History Volume 1 (1901) and is in the section by Fletcher & Martineau on Hymenoptera, which merely states “Formicoxenus nitidulus (Bewdley, Blatch)” without any details. OK, in SO77, but where exactly?

I have since found out that William Gabriel Blatch (1840-1900) was an active Midland entomologist in the 1870s and 1880’s. He was interested in many insect groups but particularly keen on beetles. He tried hard to stimulate interest in insects (Blatch 1879a) amongst members of the Birmingham Natural History & Philosophical Society (of which he was secretary for many years) and other naturalists, and his efforts included the formation of The Midland Union of Natural History Societies and The Birmingham Entomological Society. After gleaning this information from biographical section of The Coleopterist website www.coleopterist.org.uk,  I hoped to find he had written about Formicoxenus in the publications of these societies. David Antrobus kindly allowed me access to the Birmingham Natural History Society library but so far I have been unable to find any reference to Formicoxenus. I did however find a description of a “virtual” entomological foray into Wyre by Blatch (1879b) which includes an enthusiastic description of dismembering a Wood Ant nest in search of rare beetles (mymicophiles) but, alas, no mention of the guest ant! Blatch apparently published 62 notes and articles – so far I have only seen six so I have a lot of searching to do in the hope of finding more details of the first discovery of the Shining Guest Ant in Wyre Forest. It was around 130 years before the second record!