A quick response is required if thrips are to be brought under control. A small spot with thrips can become a real infestation in no time!
The temperature in particular determines how quickly the problem spreads: the higher the temperature it is, the more active the thrips are and the faster they multiply. This is why the insects feel so at home in a warm greenhouse. Other factors also play a role, such as humidity and the type of crop.
An additional point is that western flower thrips love both plant juices and pollen, multiplying much faster on flowering plants than on a crop without flowers.
A female can lay one to two hundred eggs that hatch within a few days. At 15°C/59°F, the development from egg to adult takes about 40 days. At 30 °C/86°F, it takes just nine to eleven days (it varies a bit depending on the species of thrips). And under optimum conditions, a population of western flower thrips is even capable of doubling within just four days!
Thrips are extremely tenacious and demand a great deal of determination from growers. If you're too late, you'll find yourself fighting a losing battle.