Plague thrips

Thrips imaginis

The adult females vary from pale-yellow through to dark-brown, but are typically golden-brown. The adult males are less variable and are typically pale-yellow. The body size of the adult females is variable, but is typically just over 1 mm long, whereas the males are just under 1 mm long. Like most thrips, the adults have two pairs of strap-like fringed wings. T. imaginis has antennae with seven segments and a wide gap in the row of setae on the first vein of the forewing. In live or freshly killed specimens, the ocelli are red.

Damage: Feeding damage removes the contents of cells to produce small patches with a silver appearance, an effect known as 'silvering'. On coloured petals, white or silver patches can appear where the pigment has been removed. After feeding, the adults and larvae produce anal droplets that dry to produce small dark spots. These are the same colour as the tissue, but darker, so that the spots on a purple petal would appear dark-purple. However, some flowers can contain large numbers of thrips with few, if any, signs of damage. Feeding at an early stage of bud development can produce stunted or deformed flowers and feeding at the end of flowering can produce stunted and deformed fruit.


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