The cotton aphid (Aphis gossypii) is not only a direct pest of many crops but also a significant vector of viral plant diseases. It is capable of transmitting more than 50 different plant viruses, including the economically important cucumber mosaic virus. Both nymphs and adults feed by extracting sap from plants, which disrupts nutrient flow and disturbs hormonal balance. This leads to stunted growth, leaf deformation, and in severe cases—particularly when infestations occur early in the growing season—the death of young plants.

Heavy infestations reduce yields through twisted leaf development and defoliation. In addition to direct feeding damage, Aphis gossypii produces large amounts of honeydew due to the high sugar and low protein content of plant sap. This sticky excretion coats leaves and fruit, promoting the growth of black sooty moulds (Cladosporium spp.), which further reduce the marketability of fruits and ornamentals. The presence of honeydew and mould also interferes with photosynthesis, compounding the overall negative impact on crop health and productivity.

Aphids have a complex life cycle that includes both winged and wingless adult forms, as well as a wide range of body colours. In greenhouse conditions, cotton aphids reproduce asexually through parthenogenesis, with unfertilized females giving birth to live young—also female—allowing for rapid population growth. Each individual moults four times before reaching adulthood, leaving behind white shed skins that are often visible on the plant and serve as a clear sign of infestation. Body colour varies depending on environmental conditions such as temperature, food quality, and population density. It can range from light yellow to pale green or even dark green to green-black. Larger individuals, reaching up to 1.8 mm in length, tend to be darker in colour, while those produced under crowded, high-temperature conditions are smaller (as little as 0.9 mm) and typically yellow or cream-coloured.

The cotton aphid (Aphis gossypii) can be distinguished from other aphid species by:

The colour of its two cornicles (siphunculi), which are consistently black regardless of the body colour.

Have red eyes and relatively short antennae, making them identifiable under close inspection.

Preventing cotton aphid (Aphis gossypii) infestations involves a combination of cultural and environmental management strategies that reduce conditions favourable for their development. One of the most effective methods is to start with clean, pest-free plant material and maintain strict sanitation practices in the greenhouse or growing area. Regularly inspecting plants—especially young growth and the undersides of leaves—can help detect early infestations before populations build up.

Managing weeds in and around the crop area is essential, as weeds can serve as alternative hosts for aphids and a source of reinfestation. Maintaining good airflow and reducing plant overcrowding can help make the environment less favourable for rapid aphid reproduction.

Additionally, monitoring tools such as yellow sticky traps can be useful for detecting the presence of winged aphids, allowing for early intervention. If aphids are found, promptly removing and destroying heavily infested plant material can help contain the spread and limit the population before it causes significant damage.

Several biological control agents can be used effectively to manage cotton aphid (Aphis gossypii) populations in greenhouses and other protected growing environments. These beneficial insects target aphids at different life stages, helping to suppress infestations naturally and sustainably.

Chrysopa (green lacewings) are generalist predators whose larvae are highly effective at consuming aphids. Each lacewing larva can eat hundreds of aphids during its development, making them a strong choice for hotspots or preventative introductions.

Aphidalia, containing Adalia bipunctata (the two-spot lady beetle), is another powerful aphid predator. Both the larvae and adults are voracious feeders and will actively seek out aphid colonies, including those hiding deep within plant canopies.

Aphided, which contains Aphidoletes aphidimyza, is a predatory midge. Its larvae are particularly effective against a variety of aphid species. Once introduced, the adults lay eggs near aphid colonies, and the emerging larvae feed directly on the aphids, often collapsing infestations within a couple of weeks under optimal conditions.

Aphipar (Aphidius colemani) and Aphipar-M (Aphidius matricariae) are parasitic wasps that target specific aphid species, including cotton aphid. These tiny wasps lay their eggs inside live aphids. As the wasp larva develops, it eventually kills the host aphid, leaving behind a distinctive "mummy." Over time, regular releases of these parasitoids can lead to sustained population suppression.

Choosing the right combination of these beneficials depends on the crop, climate, infestation level, and presence of other pests. A preventative or early curative strategy, along with good crop monitoring, can keep aphid numbers under control and reduce the need for chemical intervention.