Thrips
How to recognise it
Thrips are cylindrical shaped, sap sucking insects which are 3 to 4mm long and can be coloured white, yellow, brown or black. Adults have a pair of narrow wings fringed with hairs, the larvae are wingless and usually lighter in colour than the adults. They can be found on plants from spring to autumn and overwintering in the soil or leaf litter.
Lifecycle
The females, which live for about a month, can bear up to 100 eggs in that time, secreting them within plant tissues or onto the plant surface. The eggs hatch, the larvae feed, they then become non-feeding pupae and about a week later adults emerge. The adults develop their wings after the pupal stage. The whole process from egg to adult can take only a month in the summer, but much longer in lower temperatures. The adult and immature thrips overwinter in the soil or in the litter layer on top of the soil.
Why it’s a problem
A large thrips infestation can lead to the plant’s flowers, buds and leaves becoming mottled and silvery in colour as the thrips pierce the tissue to feed on the contents of the plant’s cells. Distortion of the flower, bud or leaf can occur and the insects can act as vectors for diseases such as the tomato spotted wilt virus. Plants aren’t usually killed, but they can look unsightly as a result of an attack.
The winged adults can travel long distances on thermal currents, so infestations can easily travel from plant to plant or garden to garden.
© 2012 Oak Leaf Gardening
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