The key to controlling pests in your herb crops effectively, is detecting them early and introducing beneficials at the right moment.

Pests can damage herbs in different ways depending on the nature of the plant. However there are some more common damage patterns you can look for.

• Aphids. Green Peach Aphid and the Cotton/Melon Aphid are the most common aphid pests of herbs. Damage can include stunted plant growth (especially seedlings), deformed leaves, and honeydew and sooty mould at hotspots. Aphids also transmit plant viruses.
• Caterpillars (heliothis and loopers) cause chewing damage to all stages of the plant.
• Mealybugs stunt the growth of seedlings. Their physical presence, combined with honeydew and sooty mould, renders the final product unsaleable.
• Two-Spotted Mite is the most common spider mite pest of herbs. Generally, small yellow or white spots or stripes will develop on the leaves and stems at the start of an infestation, which progresses to visible webbing that will usually kill the affected area. You may also notice distorted and discoloured leaves.
• Thrips can deform and/or discolour leaves, stems, and flowering parts. They also transmit plant viruses. Thrips can be serious pests in commercial greenhouses, especially the Western Flower Thrips. Thrips can blow in from the outside or emerge from the soil or growing media where they pupated the previous generation.
• Broad Mite and other eriophyid or tarsonemid mites are difficult to spot. Often, their presence isn't confirmed until after damage has occurred. These mites can affect all parts of the plant and typical signs include stunting, unproductive growing tips, deformed leaves and flowers, and scarred fruits.
• Whiteflies. These can be serious pests of greenhouse herb crops. It is important to confirm whether you have Greenhouse Whitefly, Silverleaf Whitefly or both, because different parasitic wasps are used control them. The presence of adult whiteflies is easy to detect and females lay their eggs on the undersides of leaves. The emerging whitefly nymph (or scale) sucks sap from the leaves. The resultant honeydew and sooty mould make the final product unsaleable. Whiteflies also transmit viruses.
• Fungus Gnat and Shoreflies. These are nuisance pests in nurseries and container growing systems. At high levels, Fungus Gnat larvae can damage the roots of seedlings and worsen existing fungal soilborne diseases. Shoreflies can spoil the visual appearance of the leaves and flowers with their droppings (also called “spotting” or “flyspecks”).