|Tussocks on the corners of a grave.|
|Yellow Meadow Ants (Lasius flavus) in a churchyard 'tussock'|
Like many ant species, L. flavus feeds on the sugary 'honeydew' produced by aphids that are tended by the colony. However, the ant-aphid relationship is more complex than this as L. flavus has 'collected' a number of subterranean aphid species (e.g. of the genera Forda, Geoica, Aphis, Tetraneura and Baizongia) which, in Britain, have lost their sexual generation associated with woody plants and are now entirely asexual on the roots and stolons of grasses. Others such as Sappaphis bonomii lay over-wintering eggs on plants above ground, and L. flavus tends them as if they were ant eggs (at the wrong time of year). Not only that, but as well as using aphids as sources of honeydew, L. flavus also uses them as prey to feed its larvae (Donisthorpe 1927, Pontin 2005). The aphids rarely disperse openly above ground level, suggesting that despite the possibility of being eaten by ant larvae, the protection of subterranean ants outweighs this risk. Further, this may effectively form a type of 'culling', keeping aphid density below levels where they tend to start producing winged forms for dispersal.
So, although this is a common and widespread species, it hides a symbiotic lifestyle that is rarely seen despite taking place beneath our feet as we walk across many an old pasture or other undisturbed grassland. I'm certainly tempted to ask permission to investigate these churchyard mounds more closely and maybe learn more about the aphids and other 'guest' invertebrates that can be found within. As the church (St. Mary's, Bishopstoke) was consecrated in 1891, there has been plenty of time for the ant community to develop. Lastly, I want to look briefly at the landscape, or 'antscape', effects of L. flavus. In an old pasture, the anthills are close together (active ones may abut or overlap old inactive ones), but their arrangement is effectively patchy and random. In the churchyard, the association with graves means that this is not the case and the anthills are arranged more or less in a grid matching the positions of graves - even where these have since disappeared - in such cases the pattern of anthills marks the outlines of old graves - ghosts in the graveyard!
|Pattern of L. flavus anthills following the locations of current and missing graves.|
Donisthorpe, H.St.J.K. (1927). Guests of British Ants. Routledge, London. [An old classic; can be a bit expensive, and a lot of the taxonomy has changed, but still worth having].
Pontin, J. (2005). Ants of Surrey. Surrey Wildlife Trust, Woking. [Maps of ant distribution in Surrey, but plenty of other more widely applicable information about British ants].
Skinner, G.J. & Allen, G.W. (1996). Ants. Richmond, Slough. [An excellent little book in the Naturalists' Handbooks series. Includes species-level keys to the British ant fauna. If you want just one book on British ants, I recommend this].
Agosti, D., Majer, J.D., Alonso, L.E. & Schultz, T.R. (2000). Ants. Standard Methods for Measuring and Monitoring Biodiversity. Smithsonian, Washington DC. [Takes a global approach with particular emphasis on the tropics and Americas, but covers a range of widely applicable techniques and ideas].