PROTECTED HERBS: Pests -
Western flower thrips, Frankliniella occidentalis and Onion thrips, Thrips tabaci

Western flower thrips;
adult larva pre-pupa pupa

Onion thrips
adult

Thrips damage:
basil, chives, mint

Biological controls

select the pest from the drop down list

Western flower thrips (WFT), Frankliniella occidentalis - This is the main species of thrips found on protected herbs in the UK Adult Adults are small and slender, approximately 2 mm long, with fringed wings held along the back. Males are yellow and females (right) are usually yellow at the front and brown at the back. The females lay eggs in plant tissue, so the eggs are not visible. The female western flower thrips on the sticky trap is shown below left and the male below right

Western flower thrips, larva The first stage larvae are very small and clear or white. The second stage larva (seen here) is yellow and about the same length as the adult. The larvae do not have wings so cannot fly.
Western flower thrips, pre-pupa There are two pupal stages, the pre-pupa and the pupa. Usually these are not visible on plants as most of the larvae drop to the ground to pupate in the compost or soil. The pre-pupae have short wing-buds and forward-pointing antennae.
Western flower thrips, pupa The pupae have longer wing-buds and backward-pointing antennae
Onion thrips, Thrips tabaci This species sometimes occurs on protected herbs in the UK. Adults are yellowish brown and look very similar to western flower thrips (WFT). Specialist examination is needed for confirmation of thrips species.
Damage Thrips feeding on the leaves cause small white flecks or patches, within which tiny black faecal spots are seen. Chives, basil and mint are commonly damaged herbs.
On chives
On basil
On mint
Biological controls Amblyseius cucumeris A small pale beige-coloured predatory mite which is active on leaves and in buds and flowers. Feeds on young thrips larvae.
A. cucumeris are usually released in controlled-release sachets on herbs (right)
Hypoaspis spp Hypoaspis miles and Hypoaspis aculeifer are ground dwelling predatory mites which feed on various invertebrates including thrips pupal stages (seen here approaching a western flower thrips pre-pupa). Hypoaspis spp. are whitish when young and develop a darker brown shield on their backs when older.
Steinernema feltiae An insect-pathogenic nematode ('Nemasys F ) is applied as a foliar spray. The nematodes enter the thrips' body and release a bacteria which kills the pest. The nematode can kill thrips adults and larvae on the plants, and also pupal stages in the ground. The photograph (right) shows a WFT pupa dissected to release a nematode (shown with the arrow) from inside its body. A group of Steinernema feltiae are shown far right
Verticillium lecanii 'Mycotal' is an insect-pathogenic fungus. It is applied as a floiar spray, promarily to control whitefly but will also kill thrips. The fungus germiates and grows on the body and can be seen as a white 'fluff'.