THE SOIL FAUNA: ANTHROPODS - The Soil - page 83

montana. This is confined to certain areas of the New Forest in Britain though it
ranges widely through Europe, southern Scandinavia and Asia, probably to the Pacific
coast. Cicadas are famous as adults for their musical 'singing' which is analagous to
the stridulation of crickets. They are also famous for their long larval life. An Amer-
ican species Magicicada septendecim is known to live for 17 years as a larva before
emerging from the ground in synchronized adult swarms. It is not known for certain
how long the British species usually lives its secretive subterranean life. J.A.Grant
made a long-term study of this species in the New Forest. Here, 6 and 7 year cycles
were observed and the full range of variability is probably 5-8 years. The larvae
( Plate 9 ) feed by sucking the root sap of various plants, most notably purple moor-
grass, but also bracken, ling, beech and birch. In parts of the USSR, there are reported
densities of 10,000 larvae per cubic metre of soil, and forest trees are severely dam-
aged, root and branch! In Britain, it is a protected species.
The mole cricket is a handsome insect 35-40mm in length when full grown
( Plate 10 ) . It is notable for its remarkably broadened and toothed fore limbs which
recall the specially modified 'hands' of the mole. Its latin name Gryllotalpa is a com-
bination of the latin names for cricket Gryllus and the European mole Talpa. It lives
mainly in underground burrows in grassy swamps and undrained pastures where it
feeds on roots and also on insect grubs. Like the cicada and our three species of native
litter-living cockroaches, it is on the edge of its range in this country, and is vulner-
able to a recession in the climate. It is now restricted to parts of Wiltshire, Hampshire,
the Isle of Wight and east Sussex, and, with the cicada, has recently been placed on
the list of endangered British species. Land drainage and pasture improvement have
reduced the areas of suitable habitat so that, nowadays, there is less scope for recov-
ery after local extinctions. It is interesting to contemplate the possible increase in such
species as a result of climatic warming through the 'greenhouse effect'. Ecologists are
now seriously considering the possible implications of a 4-5°C rise in average tem-
perature, unprecedented in the historical period, by the year 2050.
There are only a few moths whose larvae live in the soil. The tiny Micropteryx
species are considered to be very primitive because they retain mandibles in the
adults. The larvae are only a millimetre or two long and feed on fine particles of litter
in woodland soil. The swift moths are also primitive. The elongate white caterpillars
of the ghost swift Hepialus humulis attain a length of nearly five centimetres and bur-
row deeply in the soil feeding on the roots of grasses and a wide range of weeds.
They, and the smaller garden swift caterpillars, are very active when disinterred, and
are able to crawl backwards as quickly as forwards. The ghost swift is widespread
throughout Britain with populations of caterpillars in agricultural land often between
2,000 and 4,000, and sometimes up to 20,000 a hectare. Locally they can cause con-