Yellowing or distorted leaves: Aphid feeding disrupts nutrient flow, often causing young leaves to yellow, curl, or become misshapen.

Stunted plant growth: Heavy infestations can divert essential nutrients, slowing development and resulting in smaller or weakened plants.

Sticky residue (honeydew): Aphids excrete a sugary substance that coats leaves and stems, making plants feel sticky to the touch.

Sooty mold growth: Honeydew encourages the growth of black sooty mold fungi, which can cover plant surfaces and inhibit photosynthesis.

Wilting or plant death: In extreme cases, high aphid populations can cause plants to wilt or die due to excessive sap loss.

Leaf curling or twisting: Some aphid species cause physical distortion in leaves and shoots as they feed, particularly on new growth.

Aphids have a complex life cycle that allows them to rapidly adapt and spread, particularly in protected environments like greenhouses. Adult aphids occur in both wingless and winged forms, depending on environmental conditions. The wingless forms are known as apterous, while the winged individuals, or alates, develop when overcrowding, declining plant quality, or seasonal changes trigger the need for dispersal. Alate aphids possess two pairs of wings, with the front pair significantly larger than the rear, enabling them to migrate to new host plants.

For much of the growing season, aphid populations are composed primarily of viviparous females—females that reproduce asexually by giving birth to live young. These young are clonal nymphs, genetically identical to their mother, and begin feeding on plant sap immediately after birth. They grow quickly, passing through four moults before becoming adults. The accumulation of white, shed cuticles on leaves is often an early sign of aphid presence in crops.

Aphid life cycles fall into two broad categories. Host-alternating species reproduce asexually on summer hosts and migrate to winter hosts, where they reproduce sexually and lay overwintering eggs—this is called a holocyclic (complete) life cycle. In contrast, some species remain on the same host year-round and may continue reproducing asexually throughout the winter. This is referred to as an anholocyclic (incomplete) life cycle. In greenhouse environments, where conditions are stable, aphids often reproduce exclusively through parthenogenesis without ever producing eggs. However, in crops grown under cooler winter conditions—such as greenhouse strawberries—sexual reproduction and egg-laying can occasionally occur.

Aphid prevention begins with early detection and good crop monitoring. Recognizing aphids in the early stages of infestation is key to managing their populations before they cause significant damage. Aphids are small, soft-bodied insects typically under 6 mm in length, with a distinctive pear-shaped body, long antennae, and two tiny tube-like structures (called cornicles) on their hind end. While green is the most common coloration, aphids can also be yellow, black, pink, red, or even brown depending on the species and life stage. Some may also display stripes or other markings, which can help with species identification.

Aphids are often found in clusters on the undersides of leaves, where they pierce the plant tissue and feed on sap. Their slow movement and tendency to congregate in protected spots make them easy to miss without thorough inspection. In addition to leaf undersides, aphids can also be found on tender stems, buds, new shoots, flowers, and fruits, especially in rapidly growing areas of the plant.

Preventing aphid outbreaks involves a combination of cultural practices and environmental controls. Maintaining a clean growing environment by removing plant debris and weeds can reduce potential aphid breeding grounds. Many aphid species overwinter on alternate host plants, so eliminating these can help break their life cycle. In greenhouses, screening vents and monitoring incoming plant material can help prevent initial introductions. Regular scouting, especially on young or stressed plants, allows for early intervention and reduces the need for reactive chemical treatments.

By combining vigilant monitoring with sound cultural practices, growers can reduce aphid pressure and improve the effectiveness of future biocontrol strategies.

Koppert offers a range of effective biological solutions for aphid control, each targeting different life stages or types of aphids, and working well either individually or in combination as part of an integrated pest management (IPM) program.

Parasitic wasps are among the most targeted solutions we offer. These tiny, specialized wasps parasitize aphids by laying their eggs inside them. Over time, the aphid becomes a "mummy" — a swollen, tan shell — as the developing wasp larva consumes it from within. Aphipar (Aphidius colemani) is highly effective against smaller aphid species like green peach aphid (Myzus persicae) and melon aphid (Aphis gossypii). For larger aphid species such as the potato aphid (Macrosiphum euphorbiae), Ervipar (Aphidius ervi) is a better choice, due to its ability to handle bigger hosts. Aphipar-M (Aphidius matricariae) is ideal for cooler conditions and performs well on aphids like the cannabis aphid (Phorodon cannabis) and the tobacco aphid (Myzus persicae nicotianae). Another powerful wasp species, Aphilin (Aphelinus abdominalis), provides broader coverage and performs well in mixed aphid infestations and in cooler climates.

For more aggressive aphid outbreaks or when physical predation is needed, predators can be used alongside parasitoids. Chrysopa (green lacewing larvae) are voracious generalist predators that feed on aphids, thrips, and other soft-bodied insects. They are particularly effective when released early and directly into hot spots. Another strong option is Aphidalia (adult and larval stages of Adalia bipunctata, the two-spotted lady beetle), which consumes large numbers of aphids daily and is often used in outdoor ornamentals or greenhouse crops with higher pest pressure. For a consistent and sustainable predator presence, Aphidend (Aphidoletes aphidimyza) provides long-term suppression. The adults of this gall midge are highly mobile and actively seek out aphid colonies, laying eggs directly in the infestation. Once the larvae hatch, they feed directly on the aphid consuming 100s during this stage.

Together, these biological agents offer a well-rounded strategy for aphid management. Parasitoids work invisibly and steadily in the background, suppressing population growth through parasitism, while predators provide fast, visible results in high-pressure areas. When introduced proactively and with good crop monitoring, Koppert’s biologicals can dramatically reduce the need for chemical controls and support healthier, more resilient crops.

The crops listed below can be treated broadly for aphids using general biological solutions - Chrysopa, Aphidalia, or Aphidend. For all other crops not mentioned, it is important to first identify the specific aphid species present before selecting a treatment. This is because different aphid species may require different biocontrol strategies, and a targeted approach ensures more effective and sustainable control.