Pest (insect) control in hydroponics

Check foliage and roots regularly for signs of pests (and diseases). Problems can multiply rapidly if left unattended.

Insects feed off plant foliage causing leaves to turn pale and then drop. Some insects target and destroy roots (e.g. fungus gnat). They also spread disease from one plant to another via sap transfer.

Compared to growing outdoors, a controlled indoor growing environment provides the opportunity to filter the incoming air supply. This greatly assists preventing problems from pests (and diseases).

To detect the presence of insects, use a magnifying glass to routinely inspect both sides of leaves, stems, medium and roots. “Yellow sticky traps” are also useful as a forewarning (Fig 14.1).

If you do see insects, act quickly because their numbers can multiply rapidly. Isolate the plant if possible and begin treatment immediately. Contact your local grow shop for advice on the latest treatment methods.

Common insects found in hydroponic & soil plants

Spider mites (2 spotted mite)

Tiny spiders appear on the plant as pinhead sized yellowish spots. They feed on sap and their presence is indicated by plants generally looking sick. They cause mottling of leaves that eventually turn brown and fall off. The formation of tiny webs indicates the problem is well advanced.


Pear shaped body typically ~2mm long; can be any color. They suck sap from leaves causing leaves to curl.

Fungus Gnat

Appear like tiny fruit fly; ~2mm long; black with 2 wings and antennae. Their larvae eat root hairs.


Appear as ~2mm long white flies having 4 wings. They feed off plant sap causing plants to turn yellow and wilt. Usually found on the underside of leaves - gently shake the plant and watch for movement.


Appear 1-3mm long with hairy wings. They feed off plant sap causing damage to manifest as patches or streaks on the leaves.


Brown, oval and hard-bodied. They suck sap from leaves and stems.