Garden Wildlife
             Garden Wildlife
Beetles - the Order Coleoptera
 
By Andrew Halstead         Reviewed by Andrew Salisbury
 
There are more species (c400,000 described) of beetles known in the world than any other group of insects. The great British Biologist J.B.S. Haldane is alleged to have said: "If one could conclude as to the nature of the Creator from a study of creation, it would appear that God has an inordinate fondness for stars and beetles".
 
The Coleoptera is the third largest insect Order in Britain and Ireland, with more than 4,100 species recorded.  Beetles are characterised by having forewings that are thickened to form hard wing cases or elytra that are held flat over the insect’s back.  The hind wings are membranous and are hidden beneath the elytra.  Beetles vary in size from less than a millimetre in length to 50mm.  Beetles have very diverse feeding habits and occupy a wide range of habitats in gardens.
 
 
Recognising beetles
Beetle adults are tough with strong hard cuticle, and the forewings are adapted as protective shields called "elytra" (singular elytron), and not useful for flight.  The elytra are very characteristic of beetles, but could be confused with the similar protective forewings of true bugs and earwigs.  Bug forewings however fold partly over each other instead of meeting at the midline, and earwigs always have abdominal pincers.
 
Beetles also have prominent antennae, and always have chewing mouthparts. The prothorax (the front of the thorax before the wings) is tough and protective like the elytra, and the head is heavily built too.
 
Beetle life cycles
 
Beetles undergo complete metamorphosis as they develop from egg to adult.  The larval stages are often very different in appearance to the adult insect and they many occupy different habitats and have different diets.  Generally beetle larvae living in the ground or in dead wood have strong tough heads and jaws, but soft grub-like pale abdomens.  Ground beetle larvae are generally dark, tough and mobile,with the thorax with 3 pairs of legs blending into the long abdomen.  Before becoming adult, the insect will pass through a pupal stage where the adult features develop.
Note how the hard tough forewings (elytra) of this stag beetle meet precisely at the mid-line, protecting the hindwings and abdomen. Most UK beetles are like this but in some groups such as the rove beetles the abdomen isn't completely covered.
 
Beetle pages on this website  
 
We have grouped the beetles by habit because we think this may be easier for readers to follow than names of families.  We are covering:
 
  •  Pond beetles.  Several families of beetles are strongly associated with ponds.  These include the predatory
     dytiscid beetles of the Dytiscidae family, the vegetarian water beetles of the Hydrophilidae family, and 
     whirligig beetles of the Gyrinidae family
 
  •  Predatory land beetles.  These include the ground beetles of the Carabidae family, rove beetles of the
     Staphylinidae, and ladybirds of the Coccinellidae family. Larvae and adults are active predators
 
  •  Dead wood beetles.  These include stag beetles, longhorn beetles, woodworm beetles and bark beetles where
     the larvae feed on dead wood
 
  •  Carrion beetles.  These include burying beetles and hide beetles which feed larvae on dead material
 
  •  Dung beetles Larvae feed on dung
 
  •  Foliage-eating beetles. These include leaf beetles, flea beetles and weevils. Some are pests!
 
  •  Root-eating beetles.  Chafer grubs, wireworms and vine weevil grubs. Some are pests
 
  •  Pollen beetles.  Pollen-eating beetles which can act as pollinators
 
  •  Other beetles.  Many faimilies of small fungus eaters, and other more obscure garden beetles.
 
 
 
 
Websites we recommend
 
Web site of The Coleopterists Society
Mark Telfer’s beetle web site
UK Beetle Recording Beetle Families
    (very useful photos of representative beetles from British families)
Mike Hackston's keys to groups of beetles Major work in progress.
 
Books
 
Cooter, J. & Barclay, M.V.L. (2006) The Coleopterist’s Handbook. The Amateur Entomologists’ Society
Unwin, D. M. (1984) A key to the families of British Beetles. A Field Studies Council AIDGAP key
 
 
Life stages of the cockchafer beetle, Melolantha melolantha.  From the left, the ground-dwelling larva, the pupa, and the adult unfolding its wings and about to fly.
Carabid ground beetles. Left, larva of Carabus monilis, right the adult of the common violet ground beetle Carabus violacea
Beetles - the Order Coleoptera
 
By Andrew Halstead         Reviewed by Andrew Salisbury
 
There are more species (c400,000 described) of beetles known in the world than any other group of insects. The great British Biologist J.B.S. Haldane is alleged to have said: "If one could conclude as to the nature of the Creator from a study of creation, it would appear that God has an inordinate fondness for stars and beetles".
 
The Coleoptera is the third largest insect Order in Britain and Ireland, with more than 4,100 species recorded.  Beetles are characterised by having forewings that are thickened to form hard wing cases or elytra that are held flat over the insect’s back.  The hind wings are membranous and are hidden beneath the elytra.  Beetles vary in size from less than a millimetre in length to 50mm.  Beetles have very diverse feeding habits and occupy a wide range of habitats in gardens.
 
 
Recognising beetles
Note how the hard tough forewings (elytra) of the stag beetle on the right meet precisely at the mid-line, protecting the hindwings and abdomen. Most UK beetles are like this but in some groups such as the rove beetles the abdomen isn't completely covered.
 
Beetle adults are tough with strong hard cuticle, and the forewings are adapted as protective shields called "elytra" (singular elytron), and not useful for flight.  The elytra are very characteristic of beetles, but could be confused with the similar protective forewings of true bugs and earwigs.  Bug forewings however fold partly over each other instead of meeting at the midline, and earwigs always have abdominal pincers.
 
Beetles also have prominent antennae, and always have chewing mouthparts. The prothorax (the front of the thorax before the wings) is tough and protective like the elytra, and the head is heavily built too.
 
Beetle life cycles
 
Beetles undergo complete metamorphosis as they develop from egg to adult.  The larval stages are often very different in appearance to the adult insect and they many occupy different habitats and have different diets.  Generally beetle larvae living in the ground or in dead wood have strong tough heads and jaws, but soft grub-like pale abdomens.  Ground beetle larvae are generally dark, tough and mobile,with the thorax with 3 pairs of legs blending into the long abdomen.  Before becoming adult, the insect will pass through a pupal stage where the adult features develop.
Life stages of the cockchafer beetle, Melolantha melolantha.  From the left, the ground-dwelling larva, the pupa, and the adult unfolding its wings and about to fly.
Carabid ground beetles. Left, larva of Carabus monilis, right the adult of the common violet ground beetle Carabus violacea
 
Beetle pages on this website  
 
We have grouped the beetles by habit because we think this may be easier for readers to follow than names of families.  We are covering:
 
  •  Pond beetles.  Several families of beetles are strongly associated with ponds. 
     These include the predatory dytiscid beetles of the Dytiscidae family, the
     vegetarian water beetles of the Hydrophilidae family, and whirligig beetles of
     the Gyrinidae family
 
  •  Predatory land beetles.  These include the ground beetles of the Carabidae
     family, rove beetles of the Staphylinidae, and ladybirds of the Coccinellidae
     family. Larvae and adults are active predators
 
  •  Dead wood beetles.  These include stag beetles, longhorn beetles, woodworm
     beetles and bark beetles where the larvae feed on dead wood
 
  •  Carrion beetles.  These include burying beetles and hide beetles where the
     larvae feed on dead animal material
 
  •  Dung beetles Larvae feed on dung
 
  •  Foliage-eating beetles. These include leaf beetles, flea beetles and weevils.
     Some are pests!
 
  •  Root-eating beetles.  Chafer grubs, wireworms and vine weevil grubs. Some
     are pests
 
  •  Pollen beetles.  Pollen-eating beetles which can act as pollinators
 
  •  Other beetles.  Many faimilies of small fungus eaters, and other more obscure
     garden beetles
 
 
 
Websites we recommend
 
Web site of The Coleopterists Society
Mark Telfer’s beetle web site
UK Beetle Recording Beetle Families
    (very useful photos of representative beetles from British families)
Mike Hackston's keys to groups of beetles Major work in progress.
 
Books
 
Cooter, J. & Barclay, M.V.L. (2006) The Coleopterist’s Handbook. The Amateur Entomologists’ Society
Unwin, D. M. (1984) A key to the families of British Beetles. A Field Studies Council AIDGAP key