Whiteflies cause damage primarily through their feeding behavior and the secretion of honeydew. The larvae require large amounts of protein for development, prompting them to consume significant quantities of plant sap, which is high in sugar. This excess sugar is expelled as honeydew, especially in large quantities by older larvae. The act of sap-sucking weakens the plant and disrupts its physiological processes. In high populations, this feeding can cause stunted growth, leaf wilting, and defoliation—particularly under strong sunlight. These effects can significantly hinder fruit development and reduce overall yield.

The honeydew itself contributes to secondary damage. It creates a sticky surface on fruit and leaves, attracting dirt and encouraging the growth of sooty moulds (Cladosporium spp.). This black mould not only diminishes the aesthetic value of ornamental plants but also interferes with photosynthesis and transpiration, further weakening the plant. In severe infestations, affected fruit can rot, rendering it unsellable. Moreover, whiteflies are vectors for various plant viruses, adding to their economic and visual impact in both food and ornamental crops.

The greenhouse whitefly (Trialeurodes vaporariorum) undergoes a six-stage life cycle: egg, followed by four larval instars, and finally the adult stage. Though the final larval stage is often referred to as a "pupa," it is not a true pupal stage in the strict biological sense. Eggs are laid on the underside of young leaves, where the entire juvenile development also takes place. The first instar, also called the "crawler," is mobile and moves across the leaf surface to find a suitable feeding spot. After settling, the remaining larval stages become immobile and remain flattened against the leaf tissue as they feed on plant sap.

The fourth larval instar, often referred to as the pupal stage, appears as a white, oval casing surrounded by a fringe of upright waxy rods. These pupae are typically found on older leaves. Adult whiteflies emerge from this casing by pushing through a characteristic T-shaped slit. Once emerged, the adults fly to the top of the plant and tend to congregate on the underside of young leaves. Here, they feed and begin laying eggs, continuing the cycle. Adults are small, white insects coated in a fine, waxy powder and possess well-developed piercing-sucking mouthparts, which they use to extract sap from the host plant almost immediately after emergence.

Preventing greenhouse whitefly (Trialeurodes vaporariorum) infestations begins with careful crop hygiene and early monitoring. Start by inspecting new plants thoroughly before introducing them into your space—whether it's a commercial greenhouse, hobby setup, or home garden. Remove plant debris and weeds regularly, especially those in and around greenhouses or indoor grow areas, as they can harbor both whiteflies and their eggs.

Mass trapping using yellow sticky cards and roller tape is a highly effective, pesticide-free method to detect and suppress adult populations early. Whiteflies are strongly attracted to the color yellow. Hang sticky cards just above the crop canopy to monitor flying adult activity and help reduce their numbers. For larger areas, such as greenhouses or grow rooms, yellow roller tape can be suspended in horizontal or vertical runs across benches or aisles to trap large numbers of whiteflies continuously. This approach helps intercept incoming adults, slows population build-up, and provides a clear visual signal when intervention is needed.

Keeping plant vigor high through proper watering, nutrition, and environmental control can also reduce plant stress, making crops less attractive to whiteflies. Integrating cultural practices like these with mass trapping builds a strong line of defense against infestations.

Biological control of greenhouse whitefly (Trialeurodes vaporariorum) can be highly effective when implemented preventatively and supported by good crop hygiene and monitoring. Koppert offers several targeted biological solutions that work in tandem to control both adult and larval stages.

Enermix, a blend of Encarsia formosa and Eretmocerus eremicus, is one of the most widely used and reliable biological agents for whitefly control. Both species are parasitic wasps that lay their eggs inside whitefly larvae. Once parasitized, the whitefly pupae turn black or golden-brown depending on the parasitoid species. Encarsia works best in stable greenhouse environments and performs exceptionally well in long-term crops like tomato, cucumber, and ornamental plants. Eretmocerus is more tolerant of warmer and variable conditions, making the Enermix combination versatile across multiple crop types and seasons. Alternatively, Ercal (pure Encarsia) or Enstrip (cards with Encarsia) can be used if growers prefer a single-species approach.

For added protection, especially when pests are present in hot spots or when conditions favor rapid population growth, predatory mites such as Swirski (Amblyseius swirskii) or Limonica (Transeius montdorensis) are excellent complements to parasitoid programs. These generalist predators feed on whitefly eggs and young larvae, reducing early-stage survival before parasitoids can take effect. Swirski and Limonica both are particularly effective in warmer environments and can also help manage thrips populations, making it a good dual-purpose tool.

By combining parasitoids and predatory mites, growers create a robust, multi-layered biocontrol strategy that targets all stages of the whitefly lifecycle. This not only prevents population explosions but also reduces the need for chemical interventions, supporting residue-free production and pollinator safety. For best results, biocontrol agents should be introduced early and supported with monitoring tools like yellow sticky traps to track pest activity and adjust release rates as needed.