Common Garden Pests

See below for a list of the most common garden pests and the recommended biological pest control treatment.

Slugs

What to look for:

Slime trails on plants/soil surround. Cause serious damage to leaves, stems and roots both indoors and outdoors.

Treatment:

Beneficial nematodes (Steinernema)

Aphids (Greenfly/Blackfly etc)

What to look for:

Familiar to most people, often the first indication of them is the skeletal, white shed skin on the surface of leaves.

Treatment:

Ladybird beetle/larvae
Lacewing/larvae
Parasitic ‘wasp’ (Aphidius)

Vine Weevil

What to look for:

Little black beetles (about 8mm long). Eaten notches at leaf edge, grubs emerge from eggs laid in the earth around stems; grubs eat root system of the host plant.

Treatment:

Beneficial nematodes (Phasmarhabditis)

Red Spider Mite (Two spotted Mite)

What to look for:

Tiny, greenish-brown mites with 2spots in summer and turning red in autumn/winter. Mottled leaves eventually turning brown and dropping off; plant looks “sick” and there may be fine webs on the top growth.

Treatment:

Predator mite (Phytoseiulus)

Whitefly

What to look for:

Small white flies, flying about at the slightest disturbance. Whitefly are resistant to most chemicals. Biological control should be introduced as soon as the first whitefly is seen.

Treatment:

Parasitic ‘wasp’ (Encarsia)

Sciarid Fly

What to look for:

Small flies flying around the top of compost their larvae eat the roots of seedlings and plants.

Treatment:

Parasitic mite (Hypoaspis)

Leatherjackets & Chafer Grubs

What to look for:

Brown cigar-shaped grubs living in grass roots. Chafer beetles lay their eggs in the top 30mm of lawns, their grubs eat the grass roots which causes brown patches visible from August (although by this time the damage has been done).

Treatment:

Beneficial nematodes (Steinernema)

Mealybug

What to look for:

Looks like a small white woodlouse nestling in the axils of leaves or in crevices, often in ‘cotton wool’ clusters.

Treatment:

Predatory beetle (Cryptolaemus)

Thrips

What to look for:

Also called ‘Thunder Flies’, these are narrow dark grey/black, flying insects with cigar shaped yellow larvae, they suck the sap from plants and severely disfigure leaves and flowers.

Treatment:

Parasitic mite (Amblyseius)