The female thrips deposits eggs in the leaf tissue. The eggs
hatch within a few days into very mobile larvae which immediately
start to feed. After the second instar they let themselves fall on
the ground to pupate. The total development time from egg to adult
takes from 20 days at 20°C (68°F) to 12 days at 30°C (86°F). At
sufficiently high temperatures one female thrips can produce up to
200 descendants.
Thrips damage the crop by withdrawing the plant cell fluids.
Empty cells are filled with air, causing a silvery appearance, on
which dark spots (the excrements) are visible. Moreover, there exist
many more damage symptoms depending on the crop. For instance,
thrips on very young cucumber fruits give deformed fruits.
In sweet
pepper, they cause cosmetic damage on the fruits close to the
calyx. In several ornamentals, flower damage through discoloration
or deformation occurs. Only a few individual thrips are enough.
Moreover, thrips are important vectors of several viruses (e.g. tomato
spotted wilt virus, TSWV).