Ground beetles (Coleoptera: Carabidae) of cultivated land

Only few insect families can exceed in numbers the 40,000 species of carabid beetles (more than 4 percent of the known insect species). Ground beetles appear in all kind of biotopes. Most species are night-active, but they are easily caught by pitfall traps. In tropics many species are arboreal. The systematics and ecophysiology of carabids have been studied fairly exhaustively. This basic knowledge makes them suitable indicator animals for environmental studies. We have studied the effects of air pollution and pesticides on carabid communities of arable land and nursery soil. Soil chemistry, and structure at trapping site affect the species composition of carabid beetles (e.g. Pedobiologia 39:193-206, 1995). Here are some examples of the common carabid species of arable fields in eastern Finland.

Agonum sexpunctatum L.

  • Size: 6-8 mm.
  • Wings fully developed.
  • Distribution: Palaearctic. Rather common and widespread.
  • Often found in sandy and moist soils.
  • Mainly in fields and other open areas
  • Breeding period is in spring and early summer
  • Easily observed, due to bright colours
  • Active in day-time
  • Often running in the sunshine.

    • Carabus cancellatus Illiger.

  • Size: 22-27 mm
  • Wings rudimentary.
  • In open land. Prefer clayey soil with some moisture.
  • It has been a common species in arable land in Central Europe before sixties. Currently it is very rare e.g. in Germany. The heavy use of pesticides has been proposed to be main cause for the decline. In Finland, this species has spread from south-eastern part of the country to north during this century. Nowadays C. cancellatus is among the most common field-dwelling species in eastern part of the country.

    • Pterostichus melanarius Illiger.

  • Size: 12 - 18 mm.
  • Wings usually quite rudimentary.
  • Distribution: In most parts of Europe. Common in cultivated soils.
  • It prefers clayey soils.
  • The species is nocturnal.
  • The analyses of gut contents of P. melanarius has indicated that this species predate on aphids and others pests of crop plants.

    • Trechus secalis Paykull

  • Size: 3.5 - 4 mm
  • Wings reduced in small scales
  • Widely distributed in Central and North Europe
  • Occasionally very common
  • Rare in Lapland
  • Appear in woodlands as well as in meadows and fields
  • Autumn breeder

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