Aphids are tiny soft-bodied insects that reproduce rampantly and destroy the plants in our gardens. They attach to tender shoots, buds, fruits and non-woody portions of the stems and feed on the sap of plants. An aphid infestation often results in wilting and curling of the plant’s leaves and formation of distorted fruits and buds.
There are over 4,000 different species of aphids found all over the world. Most aphids have a broad range of choices of host plants. However, certain varieties of aphids such as the apple aphids attach to only a specific kind of host plant.
So, is there a safe and environmentally friendly way to get rid of aphids and prevent mass damage to our gardens and orchards?
There sure is! This article describes some of the beneficial insects that eat aphids and that can be used to control aphid infestations without pesticides.
Different categories of organisms that prey on aphids
There are several different types of organisms that prey on aphids. They may be classified as predators and parasitoids.
- Predators feed on aphids and kill individuals immediately.
- In contrast, parasitoids have a slow mechanism of action for controlling aphid infestation. They lay their eggs inside the body of their prey, where the eggs grow by utilizing the prey’s nutritional resources. Eventually, aphids perish due to lack of nutrition, while the eggs keep growing.
Aphid predators and parasitoids may further be classified into generalists or specialists.
- Generalists have a broad range of prey. Most aphid predators are generalists.
- Specialists prey only on a specific kind of prey organism. Most parasitoids specialize on a certain type of aphid.
Generalist aphid predators
While many species consume aphids, we list the most common generalist aphid predators below.
Ladybugs, ladybird beetles, or lady beetles are the most common (or at least best known) generalist aphid predators. With a bright yellow, orange, or red body marked with black dots and a large black head with white patches near their eyes, these beautiful insects are easy to spot.
Both larval and adult forms of ladybirds feed on aphids.
Adult ladybugs lay their eggs on plants with aphid colonies. Once the eggs hatch and larvae emerge out of them they start feeding on the aphid population around them.
Ladybeetles are commercially available in garden supply stores. But if you do decide to purchase ladybugs to get rid of aphids, make sure to release them in your aphid-infested garden in the evening to have maximum effect.
Nighttime is ideal for ladybugs to feed on aphids. They fly away during the day.
Alternatively, when aphid-infected plants are housed in an enclosed structure such as a greenhouse, ladybugs can be released in the structure. This way, they can’t fly away, and they will eat the aphids no matter what time of day you release them.
Many ladybugs are required to control an aphid infestation. Your situation may require multiple applications of over 1,000 ladybugs each.
In any case, the use of ladybugs is a promising solution to get rid of aphids.
Green or Brown Lacewings
Other common generalist aphid predators used in farms, greenhouses, and orchards are green or brown lacewings. Adult lacewings also lay their eggs near aphid colonies.
Available commercially in garden supply stores, green lacewings are larger than ladybugs. They can be shipped as eggs, larvae, or adults. Larvae are more likely to survive and provide quicker control.
Both larval and adult forms eat aphids, but larvae are the more consistent predators. Adults feed on honeydew, nectar, and pollen. Lacewings are routinely used as an integrated pest management strategy.
Another great example of a generalist predator used for controlling aphid infestations are soldier beetles or leatherwings. These bugs are easily identified by their elongated mustard-colored or orange-red colored body, which is covered with black patches that look like burnt spots.
Soldier beetles are soft-bodied insects that feed on other soft-bodied bugs. It is important to note that only the adult form of soldier beetles feed on aphids. And the use of soldier beetles as a pest control strategy is not a very common practice as they are not available for commercial purchase.
Damsel bugs are also common generalist aphid predators, occurring naturally in gardens, orchards, and other green spaces. They have a soft, slender greyish-brown body, with a narrow head, bulging eyes, long needle-like mouth and a pair of long antennae.
Damsel bugs pierce the aphids with their needle-like mouth and suck them dry. Both adult and nymph forms feed on aphids.
Similar to soldier beetles, damsel bugs are not available commercially for purchase and therefore their use is not typically intentional.
Other pests that feed on aphids
Apart from these insects, there are several other pests that feed on aphids and can be labeled as generalist aphid predators. These include predatory midges, spiders, ambush bugs, pirate bugs, and big-eyed bugs.
Currently, research is being done to determine the efficiency of different insect species in controlling aphid infection, particularly in situations where plants are infected with multiple aphid species.
Specialist aphid predators and parasitoids
Of parasitoids and predators that specialize on aphids, the most common are wasps.
Parasitic wasps are the most widely used specialist aphid parasitoids. There are several species of parasitic wasps that specialize on aphids.
Unlike predators, they do not attack and kill aphids outright. Instead, the female wasps deposit their eggs in the aphids’ bodies.
The larvae grow inside the body of the aphid. And as the larvae grow, the aphid bodies undergo drastic changes, becoming swollen and tan/gold in color. Eventually, adult wasps emerge out of the rear of the aphid’s body, killing the aphid.
While parasitic wasps are commercially available, various species are naturally-occurring and abundant.
Aphid wasps are predators, rather than parasites. They lay eggs in deep holes or cracks of dead branches.
They sense aphid honeydew, locate aphid colonies, and collect the aphids to carry back to their eggs. When the eggs hatch, the larvae feed on these aphids before metamorphosing into adult wasps.
IPM for aphid control
The most effective way to combat an aphid infestation in your garden is to adopt an integrated pest management strategy, which involves combining some of the most commonly used aphid eradication practices.
At the beginning of spring, when the aphid eggs hatch, spray your plants with a blast of water which will help in dislodging the aphid eggs from your plants.
Also, prune any branches that house aphid colonies or that might in the future. Spray your plants with Neem oil or other horticultural oils to remove any traces of aphids from your plants. Use natural aphid predators to eliminate aphids with minimal negative impacts on the environment and to the other species that co-exist in the space. And refrain from using insecticides as long as you can because you can end up harming the beneficial natural aphid predators more than the aphid population itself.