Figwort weevils

Figwort weevils are easily overlooked until the damage caused by the beetles and their larvae to the shoot tips and flowers becomes obvious.

Figwort weevil (Cionus sp.) on Figwort (Scrophularia sp.). Credit: RHS/Entomology.

Quick facts

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

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.

Symptoms

Plants most commonly attacked by figwort weevil include PhygeliusBuddleja 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

Control

Non chemical control

  • The weevils and larvae can be controlled by hand picking

Chemical control

  • For extensive infestations, it may be necessary to use an insecticide, such as thiacloprid (e.g. Bayer Provado Ultimate Bug Killer), acetamiprid (Bug Clear Ultra), deltamethrin(e.g. Bayer Sprayday Greenfly Killer, Bayer Provado Ultimate Fruit & Vegetable Bug Killer) or lambda- cyhalothrin (e.g. Westland Resolva Bug Killer). Organic gardeners can use pyrethrum (e.g. Py Spray Garden Insect Killer, Doff All in One Bug Spray, Bug Clear Gun for Fruit & Veg, Pyrol Bug & Larvae Killer or Growing Success Fruit & Veg Bug Killer). Pyrethrum should control newly hatched larvae but will be less successful against the adult beetles.
  • Plants in flower should not be sprayed to avoid harming bees and other pollinating insects.

Download

Pesticide for amateurs (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Biology

  • 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 on the plant stems in which they pupate
  • These cocoons closely resemble the seed pods of figwort

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