Winter Pest Myths Busted: How Biological Control Works Year-Round

Pests don’t pause for winter, and neither should your biological program. A persistent myth is that beneficial insects can’t be shipped or used effectively during colder months. In reality, beneficials ship and perform year-round, and success is driven by application timing relative to pest pressure, not just the calendar. 

 In many environments, problems are already establishing in January—making early action critical. Thripex is well suited for cooler conditions and is an effective replacement for Swirskii when temperatures drop. Ulti-Mite sachets provide strong preventative control across a wide range of humidity and temperature conditions, while Entonem targets soil-dwelling pests and Entomite-M delivers reliable fungus gnat suppression. Winter isn’t a barrier—it’s the window to stay ahead.

A common assumption in commercial production is that pest pressure disappears in winter, and that when issues appear, chemical sprays are the only practical response. Along with this is the belief that biological control products cannot ship or be used effectively during colder months. In practice, these assumptions do not reflect how pests or biological programs actually behave.

Pest populations do not disappear simply because the calendar changes. In heated greenhouses, development often continues through winter at a slower pace, allowing populations to persist and establish well before visible symptoms appear. Even in unheated or partially protected structures, pests can survive in microclimates created by crop canopy, soil warmth, and residual humidity. Outdoor ornamentals and nursery stock may also harbor pests in sheltered areas or under frost covers. Many species overwinter as eggs, pupae, or adults in soil, plant debris, or structural crevices, ready to resume activity when conditions improve. When pests surface mid-winter, the pressure has usually been building for weeks. This is why timing relative to pest development remains more important than the season itself.

Read more about overwintering and how to beat it here: Understanding Overwintering Mites, Insects and Control Options - Natural Enemies

Cold weather does not prevent biological products from being shipped. Koppert has decades of experience shipping beneficial organisms year-round, supported by rigorous quality assurance protocols. These shipping processes have been tested extensively to maintain product integrity under varying conditions, so beneficials arrive healthy and ready for application regardless of season. This proven reliability allows growers to confidently maintain biological programs without interruption.

Once applied, beneficials deliver reliable performance—even in cooler conditions. Winter isn’t a barrier; it’s a factor we’ve mastered. With decades of experience and rigorously tested shipping protocols, Koppert ensures biological control works year-round when implemented correctly. For outdoor growers concerned about cold tolerance, explore our Winter Solutions. Strategic adjustments—like timing releases and optimizing placement—are simple steps that keep your program effective and ahead of pest pressure.

Spraying isn’t the only option—and it doesn’t have to exclude beneficials. Chemical tools can still play a role in winter, but they work best when integrated thoughtfully with biological control. Many growers default to chemicals in winter, assuming it’s the only viable path. That’s not the case. Biologicals work in winter—and they set you up for success in spring by reducing baseline pest pressure. When needed, sprays can still be part of an integrated program without disrupting beneficials. To make it easy, we’ve put together a detailed guide on which products are safe to combine with beneficials: Pesticide Compatability Database. If you need assistance finding which beneficals are right for your environment, reach out to our customer service agents via live chat, we're avaialble via the button at the bottom right-hand corner of the screen. 

Winter can reduce pest pressure, but it often leaves reservoirs behind. Outdoor growers experiencing freezing temperatures may see a number of pests recede; some will die, while others overwinter. For indoor growers, this reset can be minimal. Residual plant material, incoming shipments (liners, plugs, cuttings), and warm microclimates—such as along heating pipes, under benches, and near utility runs—sustain overwintering eggs, pupae, mummies, and diapausing adults. Where resets occur through crop removal, outdoor beds, or sanitation, early colonization often originates from overwintering hosts at perimeters and from incoming plant material. Once temperatures rise, even light carryover can accelerate problem populations. A winter plan that times releases, targets reservoir zones, and optimizes placement keeps biological control effective and positions your program ahead of spring pressure. Managing this phase effectively determines whether spring starts ahead or begins in catch-up mode.