Ants in the plants!
Tim Gardiner 2 Beech Road, Rivenhall, Witham, Essex, tg@writtle.ac.uk
Whilst cutting the grass in my garden at Rivenhall near Witham (TL 8217) in the summer
of 2007, I felt a sudden bump and heard the mower blades grinding against what I
thought was a large stone. The grass was quite long (10 cm) as I try to manage the
garden at a relatively low intensity so as to encourage wildlife. Upon inspection of the
ground I discovered that I had hit the makings of an ant hill. Closer inspection revealed
large numbers of Yellow Meadow Ants Lasius flavus scurrying back into their underground
nest. High densities of ant hills made by Yellow Meadow Ants are usually only found in
old meadows and pasturelands that arc centuries old, so it was a surprise to find them in a
rural back garden. The ants had made a good start at building the nest that I'd just demolished
and the location they had chosen received plenty of early morning sunshine.
Yellow Meadow Ants are known to build colonies of between 10,000-24,000 individuals
and they often build towards dawn sunshine as it warms up the nest quickly (Moore,
2002). Nests are typically built up at 10 cm a year and can be 0.5 m in height and 1m
in diameter when completed (Moore, 2002). Ant hills are known to have a diverse flora
(see Tarpey 2001) and are important for insects such as the Field Grasshopper Chorthippus
brunneus (also found in the back garden) which use them as sites to bask as young
immature nymphs (bare earth can be as hot as 50°C in summer) before the adult female
returns to lay her eggs in the soil after mating.
Where the Meadow Ants came from is a bit of a mystery although the neighbour's
garden is very untidy with plenty of long, uncut grass that the ants could have inhabited
before spreading into my back garden. It is possible that the lawns of the gardens may
be remnants of old meadowland that existed before the housing estate was built. Could
this ant persist in untidy gardens for decades after the meadows were incorporated into
lawns for the new houses? It is also possible that they came from more favourable
grassland habitats on the edge of nearby Tarecroft Wood or Rivenhall Thicks, indeed
Harvey (1998) describes woodland edges as particularly favourable for this common
ant which is rare in intensively managed farmland.
Wherever the ants came from they are not there now, accidental destruction of their new
hill seems to have driven them out of the garden altogether as none have been seen in
2008. Harvey (1998) suggests that this ant is occasionally found in undisturbed gardens,
it is even found in his own in Grays, so it is worth looking out for when mowing.
References
Harvey, P.R. (1998) The modern distribution of ants (Hymenoptera: Formicidae) in
Essex with their regional rarity and threat status. Essex Naturalist (New Series)
15: 61-111.
Moore, S. (2002) The Yellow Meadow Ant Lasius flavus: a spatial analysis of its nest
distribution. Essex Naturalist (New Series) 19: 107-112.
Tarpey, T (2001) The Bryophyte flora of the anthills at Old Hall Marshes. Essex
Naturalist (New Series) 18: 169-176, plus correction Vol. 19: 160-163.
Essex Field Club Newsletter No. 59, May 2009
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