Figwort weevils are easily overlooked until the damage caused by the beetles and their larvae to the shoot tips and flowers becomes obvious.
What are figwort weevils?
Figwort weevils are several closely related Cionus species of beetles. Both the adult weevils and the grub stage spoil the appearance of their host plants by eating the foliage and flowers.
Plants most commonly attacked by figwort weevil include Phygelius, Buddleja globosa, Scrophularia and Verbascum.
- Several species of weevil (Cionus species) cause partly eaten and dried up foliage, particularly at the shoot tips. There is also likely to be damage to the flower buds
- The adult beetles are black and greyish white and are up to 4-5mm (about 1/8in) long, with one or two black circular marks where the wing cases meet
- The larvae are up to 6mm (about ¼in) long and are slimy, yellowish-brown grubs with black heads
- The larvae feed on leaves by grazing the surface of the leaf. The remaining damaged tissues dry up and become brown or white
Non chemical control
- The weevils and larvae can be controlled by hand picking
- Spray with an insecticide containing deltamethrin (Bayer Sprayday Greenfly Killer), or with thiacloprid (Bayer Provado Ultimate Bug Killer)
- If it is necessary to spray while plants are in flower, do so at dusk in order avoid harming bees
Pesticide for amateurs (Adobe Acrobat pdf document outlining pesticides available to gardeners)
- Adult weevils overwinter in the soil and leaf litter
- They emerge in May and June when they seek out host plants on which they lay eggs
- There are two generations during summer between May and late August
- When fully grown, the larvae spin spherical brownish cocoons, in which they pupate, on the plant stems
- These cocoons closely resemble the seed pods of figwort
Common name Figwort weevils
Scientific name Cionus species
Plants affected Figworts (Scrophularia species), buddleias - particularly Buddleja globosa, Phygelius species and Verbascum species
Main symptoms Small greyish-white beetles with black circular marks on the wing cases, or slug-like beetle larvae, are present on the plants. Leaves at the shoot tips and flowers are eaten
Most active May-August