Pests: find out more LEAFMINER

Leafminer

The Pest

There are four leafminer species which are of importance on greenhouse crops:-

» CHRYSANTHEMUM LEAFMINER (Chromatomyia syngenesiae)
Apart from chrysanthemums this leafminer has a wide host range which includes many common nursery weeds.

» TOMATO LEAFMINER (Liriomyza bryoniae)
The main hosts are tomato and cucumber but it can also colonise a limited number of weed species.

» SERPENTINE (OR FLORIDA) LEAFMINER (Liriomyza trifolii)
This notifiable pest attacks most crops and weeds and is resistant to many pesticides.

» SOUTH AMERICAN LEAFMINER (Liriomyza huidobrensis)
This is also a notifiable pest and has the same wide host range and resistance to pesticides as the serpentine leafminer.

Once established on a nursery this pest becomes a persistent problem likely to occur annually.

Leafminer mines

Leafminer larva

Leafminer adult

Adult female leafminers feed on sap by probing the upper surface of leaves. Obvious white spots soon appear where probing has occurred. Eggs are laid at some of these sites which hatch after about a week. The larvae tunnel within the leaf causing typical mines. The mines get wider as the larva grow and moult. After 10-20 days pupae are formed.

With chrysanthemum leafminer, pupation takes place in the leaf. Adults emerge from pupae which are attached to the plant. However, with Liriomyza species, pupae become detached from the leaf tissue during pupation and usually fall to the floor before hatching. In summer these pupae emerge in roughly 10 days. Pupae produced in autumn by Liriomyza species, may not emerge for several months and provide an effective overwintering mechanism for the pest. Chrysanthemum leafminer survives in various stages of its lifecycle on weeds and in crop debris.