Have you got chilli thrips?

What are they?

Chilli thrips are tiny insects less than 2mm in length. These thrips puncture a hole in plant cells and suck up the sap. They feed on roses, all citrus and their hybrids, as well as a range of fruit and vegetables and are most active during spring, summer, and autumn.

Chilli thrips can have many generations in a single year (all going into the family business with the aim of destroying your roses!) and populations can build up over time.

Masters of disguise

Spotting these sneaky pests is no easy feat. They're experts at hiding in the nooks and crannies of plants, like deep within flowers or under leaves. But fear not! Keep an eye out for early signs of damage, like discoloured leaves with black dots or light brown spots. If you're suspicious, a magnifying glass can reveal their torpedo-shaped bodies.

• About two millimetres long

• Elongated, flat shaped body

• Coloured pale or translucent to black

• Adult chilli thrips have four feathery wings

• Very difficult to distinguish from other thrips species with the naked eye

• One way to confirm their presence is to cut some of the damaged foliage and shake it over a piece of white paper. If you see tiny insects coloured pale or translucent to black, and specks of black dung, then you have chilli thrips. It is the thrips larvae that feed on plant tissues that are responsible for most of the plant damage.

There are signs to look out for to confirm they are hanging out in your garden.

Damage

• Early symptoms include a clear discoloration of the leaf with black dots (faecal secretions).

• Light brown spots on leaves, which may curl.

• In cases of very severe infestation, the leaves may entirely dry up.

• Wrinkled leaves with distinctive brown scarring along the leaf veins, flower buds, and the calyx or outer casing of fruit.

• Mosaic patches on plants, in which the top layer of the tissue is undisturbed and a window or clear tissue in evident. Chilli thrips cause this by sucking up the liquid from plant cells; mainly from the leaves, but also the petals, shoots and fruits.

• Adult thrips also feed on the underside of leaves.

• Deformed shoots or flowers of affected plants, caused by toxic substances in the saliva of the pest.

What you can do

If you've got a full-blown infestation, it's time to bring out the big guns. Consider pruning off damaged parts and using insecticidal soaps or oils to control them. Just remember to follow the instructions on the label carefully.

Don’t kill off the good bugs!

Always check for beneficial insects and pollinators before spraying anything on your plants, organic, botanical, or systemic. Create a bee-friendly garden

More information is available at www.agric.wa.gov.au