Insect netting is usually made of woven or knitted polyethylene and polypropylene and designed to exclude pests from greenhouse crops, including fresh produce, fruits, nursery stock, cut flowers, houseplants, annuals and perennials.

Gonzalez says, “Most insect nets are manufactured from HDPE (high-density polyethylene). This material is generally preferred for professional greenhouse applications because it offers better UV resistance, durability, tensile strength, and dimensional stability. However, yarn quality, the weaving process, and the UV stabilisation package are often more important than the polymer itself. The key differentiator is not simply the material, but the combination of proprietary yarn design, uniform hole size, thin yet durable filaments, and consistent manufacturing quality. These factors allow high exclusion levels without sacrificing airflow.”

Some nettings can contain additives such as aluminium strips that help to increase their effectiveness against pests. However, from a production perspective, it is important to consider their impact on light transmission and spectral quality.

Modern insect screens increasingly use transparent monofilament yarns to maximise transmission of photosynthetically active radiation (PAR). Every percentage point of light transmission can contribute to crop photosynthesis, yield, stem quality, flowering, and production efficiency. Gonzalez says, “Reflective materials, coloured yarns, or coloured films may provide additional pest-deterrent effects, but they can also alter the spectral composition of incoming sunlight. Changes in the PAR spectrum may affect plant responses such as morphology, internode length, flowering, and crop uniformity. For this reason, many greenhouse growers prefer insect screens that combine effective pest exclusion with high transparency, maximum PAR transmission, and minimal spectral distortion, preserving the natural light environment while maintaining crop productivity.”

Recent research from the University of Tokyo showed that red-coloured nets significantly reduced onion Thrips pressure compared with conventional black or white nets. In field trials, crops protected by red nets required 25-50 per cent less insecticide than uncovered crops. Researchers propose that red nets interfere with insect visual perception and host-finding behaviour. The concept is often described as “optical pest control.” Red nets appear to provide a behavioural deterrent in addition to any physical barrier effect.

Jorge Gonzalez finds the concept promising, particularly for Thrips management. “However, important commercial questions remain including: Does it work across multiple pest species? Is the effect stable across climates? What is the interaction with crop physiology and light quality? Does the benefit justify any increase in cost? I believe more validation is still needed before red nets become a mainstream greenhouse standard.”

Growers can perceive the high upfront capital cost as a drawback of insect netting. Gonzalez says, “Prices vary widely depending on region, hole size, installation method, greenhouse height, and roof versus sidewall installation.” To give you an extremely rough market indication: for whitefly exclusion, prices vary between €1.00-1.80/m², while Thrips exclusion requires an investment of between €2.75-4/m². Prices will differ from country to country depending on tariffs or other logistics costs that may affect importing the goods and transporting them to the final location. For a professional project, it is better to discuss lifecycle cost rather than initial cost.

Pondering the economic benefit of durable insect netting in greenhouse-grown ornamentals, Gonzalez says the highest ROI is usually found in crops with high value per m², low tolerance for aesthetic damage and strict phytosanitary requirements. Roses, chrysanthemums, gerbera, lilium, carnations, breeding material, and young plants make excellent ROI candidates. Simply because the economic impact of Thrips, whiteflies, aphids, virus transmission, and petal damage in such crops is often much larger than the cost of the insect net itself.

Roses and chrysanthemums stand out as particularly strong candidates because Thrips directly affect saleable quality, while virus pressure can be significant and export standards strict.

When it comes to greenhouse insect netting, we usually talk about keeping harmful insects out, but what about keeping beneficial insects in? Gonzalez says, “Many IPM programmes rely on predatory mites and bumblebees. When beneficial insects are not established due to large pressure of pests, their effectiveness declines, with additional releases being required. Keeping beneficials inside can therefore generate real economic value. Svensson specifically highlights that insect nets can help keep beneficial insects inside while excluding harmful pests, improving the effectiveness of biological control programmes.”