Aphids and Their Peculiar Parasites

Oct 27, 2025

Written by Elaine Sawyer

The race is on for survival. Aphids are simple little bugs, living their carefree life on plants around the world. But many insects find them to be a great food source - ladybugs, lacewings, hoverflies and more. The answer to this variety of predators? Make more aphids! Currently, one green peach aphid can give rise to 13 million aphids within five generations. Because of asexual reproduction and live birth, aphids can rapidly overrun a greenhouse or garden. This is the main reason to have a vigorous scouting program and release predators preventatively. There is no way a single human can overcome the power of these aphid numbers. We need to enlist the help of natural enemies.

Parasitoids wasps are a part of the aphid control picture. These tiny creatures lay an egg inside the aphid host. This gives the new wasp shelter (a cozy little aphid mummy hut) and food as it develops and finally exits the host leaving behind an empty shell and a dead aphid.

The terror of things so small. There is another parasitoid that will lay an egg inside of an already parasitized aphid. Two parasites in one aphid, but the hyperparasite feeds on the developing wasp and wins this battle. These frightening bugs occur naturally and are usually a problem in late summer when conditions are favorable. They can wipe out an Aphidius population and are especially disruptive to a banker system, so keep an eye out for their tell-tale sign, a jagged exit hole as they leave the aphid mummy in contrast to a smooth round exit hole from an Aphidius.

Watch out for these creepy little parasites in late summer and utilize a diversity of aphid predators like lacewing larvae (aphid lions) and Aphidoletes. Start releases early, before the 13 million arrive. Another way to manage hyperparasites is to remove aphid banker systems in August to eliminate a source of aphid hosts. Leaving the greenhouse empty for several months can also help to clear out aphids.

One study observed that parasitized aphids leave the colony after parasitism, possibly for the primary parasitoids to avoid hyperparasitism. As always, having a plan will help your plants not only survive, but also thrive. Contact a technical sales specialist at Sound Horticulture for help preparing for the aphid season ahead.