The Slender Groundhopper Tetrix subulata in Wanstead Park
On 24th April 2009 I had a look at one of the very overgrown outcrops of land that form the sculpted south edge of Heronry Pond. On what is left of a track that leads almost un-noticeable off the Northumberland Avenue Strip, an insect flew across my feet and landed nearby - apparently a grasshopper. I couldn't understand why a fully-grown grasshopper was around at this time of year, so determined to take a photograph as a record. It was from the photograph that I later identified it as a ground-hopper, an insect closely related to grasshoppers and crickets.
There are only four species of ground-hopper to be found in Britain, and they are found in a variety of places where there is some grass cover. However, they don' t favour extensive grass cover so tend not to be found in the same type of habitats where we would expect to see grasshoppers.
They are active by day, and their activity depends on the temperature. 24th April wasn't a cold day, but it was April and I wouldn't have expected to find grasshoppers so early in the year. However, a major difference in behaviour between grasshoppers and groundhoppers is that the latter survive the Winter as adults and may be active all the year.
In Essex only two species are recorded on the Essex Field Club's database: the Common Groundhopper Tetrix undulata and the Slender Groundhopper Tetrix subulata, so it was likely to be one of these.
Two major differences became apparent: groundhoppers differ from grasshoppers in that their pronotum extends to the tip of the abdomen, whereas in grasshoppers it is much shorter. The Common Groundhopper has relatively short hind wings and is flightless, whereas the Slender Groundhopper wings reach right to the tip of its longer pronotum. That fact was clear from the photographs, and the fact that it flew across my feet helped too! The Common Groundhopper also favours somewhat drier situations, whereas the Slender Groundhopper is often found in damper ones; tangled vegetation next to Heronry Pond meets that criteria. The creature was then a specimen of the Slender Groundhopper Tetrix subulata.
Finally, it is interesting to note that this is the only record of this species in the whole of Epping Forest. I hadn't seen one before, and I haven't seen one since.
Paul Ferris, 25th April 2009