156
Q. R. POTTS AND a. P. VICKERMAN
patchy distribution of the larvae is that many of the adults migrate
into spring sown-cereals from first-year undersown leys and from
certain permanent pastures. Samples from cereals near such areas had
higher densities of larvae. In 1971, for example, larvae were present in
102 of 210 samples from cereals. Fifty of these were within 600 m of an
undersown ley. By comparison only 23 of 108 samples which did not
contain larvae were within 600 m of an undersown ley (x2 = 21.5,
P < 0.001). Usually more than 30% of the cereal acreage was undersown
in traditional ley farming rotations. In many western counties the
percentage is unchanged, but less than 5% of cereals are now undersown in East Anglia.
After Dolerus, the most important genus was Pachynematus; the
most numerous species was P . xanthocarpus (Hartig). Another important species was Tenthredopsis nmsata (L.). The larvae of nearly all the
other species fed on weeds; for example, Aglmstigma aucupariae
(Klug) and A . fulvipes (Scopoli) on Galium spp., Ametmtegia glabrata
(Fall.) on Polygonum spp., Pachyprotmis rapae (L.) on Scrophularia,
and Athalia spp. on various weeds (Lorenz and Kraus, 1957).
The wheat stem sawfly Cephus pygmaeus (L.) was present in some
crops of spring wheat but was not of any economic importance.
F. C O L E O P T E R A
1. Introduction
Cereal pests are relatively scarce in the British Coleoptera. Perhaps
the best known of the pest species belong to the Elateridae. The
larvae are normally inhabitants of grassland but can cause severe
damage to cereal crops during the first three or four years after grass
has been ploughed in. In 1965-1966, 1 307 116 ha of cereals were sown
with seed which had been dressed with y BHC, the justification being
wireworm control (Anon, 1969). Elateridae are now scarce in our
study area although there were several damaging attacks in the 1950’s.
All cereal seed in this area has been dressed for many years and this
appears to be the main reason for the long-term decline of these pests
even in ley farming areas (e.g. Maskell, 1959). The main species now
present are in the genus Agriotes and Athous haemrrhidulis (F.).
Other Coleoptera which may occasionally become sufficiently
abundant to cause damage are the cereal leaf beetle Lemu melanopa
(L.), and the flea beetles Phyllotreta vittula Redt., Crepidodera ferruginea
(Scop.) and Chaetocnem hrtensis (Geoff.). Although these species are
only minor pests in Britain, they frequently cause considerable damage
in Europe and America.
Q. R. POTTS AND a. P. VICKERMAN
patchy distribution of the larvae is that many of the adults migrate
into spring sown-cereals from first-year undersown leys and from
certain permanent pastures. Samples from cereals near such areas had
higher densities of larvae. In 1971, for example, larvae were present in
102 of 210 samples from cereals. Fifty of these were within 600 m of an
undersown ley. By comparison only 23 of 108 samples which did not
contain larvae were within 600 m of an undersown ley (x2 = 21.5,
P < 0.001). Usually more than 30% of the cereal acreage was undersown
in traditional ley farming rotations. In many western counties the
percentage is unchanged, but less than 5% of cereals are now undersown in East Anglia.
After Dolerus, the most important genus was Pachynematus; the
most numerous species was P . xanthocarpus (Hartig). Another important species was Tenthredopsis nmsata (L.). The larvae of nearly all the
other species fed on weeds; for example, Aglmstigma aucupariae
(Klug) and A . fulvipes (Scopoli) on Galium spp., Ametmtegia glabrata
(Fall.) on Polygonum spp., Pachyprotmis rapae (L.) on Scrophularia,
and Athalia spp. on various weeds (Lorenz and Kraus, 1957).
The wheat stem sawfly Cephus pygmaeus (L.) was present in some
crops of spring wheat but was not of any economic importance.
F. C O L E O P T E R A
1. Introduction
Cereal pests are relatively scarce in the British Coleoptera. Perhaps
the best known of the pest species belong to the Elateridae. The
larvae are normally inhabitants of grassland but can cause severe
damage to cereal crops during the first three or four years after grass
has been ploughed in. In 1965-1966, 1 307 116 ha of cereals were sown
with seed which had been dressed with y BHC, the justification being
wireworm control (Anon, 1969). Elateridae are now scarce in our
study area although there were several damaging attacks in the 1950’s.
All cereal seed in this area has been dressed for many years and this
appears to be the main reason for the long-term decline of these pests
even in ley farming areas (e.g. Maskell, 1959). The main species now
present are in the genus Agriotes and Athous haemrrhidulis (F.).
Other Coleoptera which may occasionally become sufficiently
abundant to cause damage are the cereal leaf beetle Lemu melanopa
(L.), and the flea beetles Phyllotreta vittula Redt., Crepidodera ferruginea
(Scop.) and Chaetocnem hrtensis (Geoff.). Although these species are
only minor pests in Britain, they frequently cause considerable damage
in Europe and America.