Most weevils and leaf beetles have a single generation a year and will overwinter as pupae or adult beetles. Eggs are laid on or near suitable host plants, with the larvae subsequently feeding on the foliage or roots. When fully fed, the larvae of most species pupate in the soil but those of figwort weevils pupate in spherical cocoons attached to the stems of their host plants.
Role of foliage-eating beetles in gardens
Several flea beetles, particularly some Phyllotreta species, feed as adults by rasping small holes in the foliage of brassicas and related plants, such as wallflower, radish, turnip, swede and rocket. Altica species sometimes damage the foliage of fuchsias. Other garden plants that can be badly damaged by larvae and adults of leaf beetles include lilies and fritillaries defoliated by red lily beetle, Lilioceris lilii; rosemary and lavender by rosemary beetle, Chrysolina americana; asparagus by asparagus beetle, Crioceris asparagi; Viburnum tinus and V. opulus by viburnum beetle, Pyrrhalta viburni; water lily by water lily beetle, Galerucella nymphaeae.
Vine weevil, Otiorhynchus sulcatus
and other Otiorhynchus
species, eat notches in leaf margins on a wide range of garden plants. However, this is a more serious pest in its larval stage, see our page on Root beetles
. Broad bean and pea foliage has regular U-shaped notches eaten in the leaf margins by adult pea and bean weevil, Sitona lineatus
. The shrubs Phygelius, Verbascum
and sometimes buddleia foliage and flowers are eaten by adults and larvae of figwort weevils, Cionus
species; various deciduous trees have their foliage eaten in late spring by adult leaf weevils, Phyllobius species.
While we prefer not to think too much about killing garden invertebrates, there is excellent tips on control in the RHS Advice pages
- use the search facility.
A North American weevil, Stenopelmus rufinasus
, is available for use in the UK as a biological control of the invasive pond weed Azolla
known as water fern. This floating non-native plant rapidly covers the water surface and reduces the amount of sunlight reaching submerged water plants.
Other sources of information
Cox, M. L. (2007) Atlas of the seed and leaf beetles of Britain and Ireland. Pisces Publications
Hubble, D. (2012) Keys to the adults of seed and leaf beetles of Britain and Ireland. Field Studies Council
Morris, M. G. (1997) Handbooks for the Identification of British Insects Vol 5 part 17a. Broad-nosed weevils
Coleoptera: Curculionidae (Entiminae). Royal Entomological Society
Morris, M. G. (2002) Handbooks for the Identification of British Insects Vol 5 part 17b True weevils (part I) Coleoptera: Curculionidae (subfamilies Raymondionyminae to Smicronychinae). Royal Entomological Society
Morris, M. G. (2008) Handbooks for the Identification of British Insects Vol 5 part 17c. True weevils (part II)
Coleoptera: Curculionidae (Ceutorhynchinae). Royal Entomological Society
Morris, M. G. (2012) Handbooks for the Identification of British Insects Vol 5 part 17d. True weevils (part III)
Coleoptera: Curculionidae (Curculioninae, Baridinae and Orobitidinae). Royal Entomological Society