Common name: Thunder flies
These insects are often abundant in flowers and on leaves during the summer months.
They feed inside developing flower buds and in the newly expanding leaves of plants.
There are a number of different types of thrips, where each type can be found on different types of plants.
Susceptible plants include: Chrysanthemum, Gladioli, Impatiens, Pea, Privet and Tomato.
Western Flower Thrip
With the aid of a magnifying glass, these minute insects can be seen as long thin cigar-shaped insects in various colours of yellow, brown and or green.
They feed by burrowing into plant tissue of developing leaves and buds, where they suck the sap from plant tissue.
This can result in silver mottling of affected leaves and petals, and severe infestations prevent normal flowering.
Damage tends to occur outdoors from June to September,and as early as April in the greenhouse.
During the feeding process, it is quite common for viruses to be transmitted to host plants
They do not generally kill plants, but they can make them look limp / tired and often unsightly.
The adults lay their eggs on the leaf, and then the larvae emerge to feed on the plant growing buds and flower buds.
Young thrips (larvae) are similar to the adult, but without wings.
The very young ones are white, and the older ones yellow-brown.
The larvae live on the plant, but when they pupate the pupa often drops to the soil.
The pupae may hide on the potting compost for upto several months before the pupating adults emerge.
They are easily trapped on yellow sticky cards this also gives a visual record of their presence.
They can also be controlled with insecticide, if applied as soon as the first symptoms are seen.
It has been found that garlic plants placed strategically around the greenhouse are an effective way to repel thrips.
Biological control can be achieved by using the predatory mite amblyseius cucumeris.