February and Thrips: What Changes in Reproduction and Why It Matters

For many growers, February is when thrips pressure becomes noticeable. This timing is not random. February represents a biological shift in thrips reproduction and population momentum that has direct implications for how pressure develops heading into spring(and why proactive management now is critical).

Thrips are rarely absent during winter. In January, populations are often present at low levels, developing slowly due to cooler temperatures, lower light levels, and reduced plant growth. During this period, reproduction continues, but at a pace that can feel manageable or even invisible. What changes in February is not presence, but speed. As light levels increase, day length extends, and crops begin pushing more active growth, thrips respond quickly. Development time shortens, egg laying increases, and the transition from slow population growth to accelerating population growth begins.

This acceleration is the signal to front-load your IPM program. Introducing predatory mites such as Amblyseius swirskii or Neoseiulus cucumeris early, before populations spike, can prevent larvae from establishing. Sachets placed throughout the crop or broadcast applications work well for crops with active growth. For crops that can support them, adding Orius (Minute Pirate Bug) now provides a predator that feeds on all thrips stages, including adults, helping break overlapping generations before they compound.
Even relatively small environmental changes can have a meaningful impact on thrips reproduction. More consistent temperatures, particularly overnight, combined with increasing natural light and fresh plant tissue, create conditions that favor faster life cycles and higher survival rates. What may have taken weeks to develop earlier in winter can take significantly less time by mid to late February. As a result, populations that appeared stable in January can begin increasing rapidly without obvious warning signs.

This is why environmental adjustments matter. Maintaining moderate humidity (50–70%) favors beneficials and reduces thrips egg survival. At the same time, sanitation—removing plant debris, weeds, and cleaning floor crevices where pupation occurs—removes hidden reservoirs that fuel population growth.

February is also the point where management timing becomes more critical. Earlier in winter, slower development allows more flexibility in response. As reproduction accelerates, that flexibility narrows. By the time feeding damage or adult movement is easy to observe, multiple generations may already be established. At that stage, decisions are often made under tighter constraints, with fewer low-impact options available.

To stay ahead, increase sticky trap density and intensify scouting now. Focus inspections on new growth and flowers where thrips concentrate. Weekly scouting is essential as development speeds up. If populations begin to rise, microbial biocontrols like Beauveria bassiana or Isaria fumosorosea can be layered in. These work best under moderate humidity and complement predators without disrupting your IPM program. Avoid broad-spectrum sprays that kill beneficials and often lead to rebound thrips pressure; if chemical intervention becomes unavoidable, choose selective products compatible with biologicals.

What happens with thrips in February has an outsized effect on March and April. Populations established now do not disappear as weather continues to improve; they compound. Programs that enter spring with low baseline pressure have more room to maneuver, while those starting behind spend valuable time catching up. For this reason, February is best understood as a transition point—when thrips biology shifts from slow winter development to sustained population growth.

Understanding this change allows growers to anticipate pressure rather than react to it. February is not about the first appearance of thrips, but about recognizing when reproduction and population momentum begin working against you—and acting decisively with preventative releases, environmental fine-tuning, and layered biological tools before the window of flexibility closes.