Dozens of insects, birds, and spiders feed on aphids, making them one of the most heavily predated pests in any garden. The most effective aphid predators are ladybugs, lacewing larvae, hoverfly larvae, and tiny parasitic wasps. A single ladybug can eat around 50 aphids per day, and many of these natural enemies are already present in your yard if you know what to look for.
Ladybugs
Ladybugs are the most recognized aphid predator, and their appetite backs up their reputation. A single adult ladybug eats roughly 50 aphids a day, adding up to about 5,000 over its lifetime. Both adults and larvae feed on aphids, though the larvae (small, dark, alligator-shaped insects that look nothing like the familiar red-spotted adult) are equally voracious. If you spot clusters of these odd-looking larvae on your plants, leave them alone. They’re doing serious work.
Lacewing Larvae
Green lacewings are delicate, pale-green flying insects you might notice near porch lights at night. The adults are mostly harmless to aphids, but their larvae are a different story. Nicknamed “aphid lions,” lacewing larvae are small, grayish-brown, and shaped like tiny alligators with long curved jaws. Each larva devours 200 or more aphids per week during its development. They’re aggressive searchers with high dispersal ability, meaning they actively roam plants hunting for prey rather than waiting for aphids to come to them.
Hoverfly Larvae
Hoverflies (also called syrphid flies or flower flies) look like small bees or wasps hovering near flowers, but they don’t sting. Adults feed on pollen and nectar. Their larvae, however, are dedicated aphid predators. Each hoverfly larva consumes up to 400 aphids before it matures. The legless, maggot-like larvae lift their heads to feel for prey, grab aphids, suck out their insides, and discard the empty exoskeleton. When hoverfly larvae are abundant in a garden, they can reduce aphid populations by 70 to 100%.
Parasitic Wasps
Parasitic wasps in the genus Aphidius are tiny (just a few millimeters long) and don’t sting humans. They kill aphids from the inside out. A female wasp lays a single egg inside each of about 100 aphid nymphs. The wasp larva hatches and feeds on the aphid’s insides over the next week or so, eventually killing it. The dead aphid swells into a crusty, golden-brown “mummy” stuck to the leaf surface. If you flip over an infested leaf and notice papery brown aphid shells, some with small round exit holes, parasitic wasps are already at work. Each species parasitizes at least 40 different aphid species, and they complete a full generation in about two weeks during summer, so populations build quickly.
One thing worth knowing: the aphid looks normal for about a week after being parasitized. That means the percentage of aphids already doomed is always higher than the number of visible mummies suggests.
Birds, Spiders, and Other Predators
Insects get most of the credit, but several other animals eat aphids regularly. Small songbirds like wrens, chickadees, and titmice pick aphids off stems and leaves, especially when feeding nestlings. Spiders catch aphids both in webs and by active hunting on plant surfaces. Predatory true bugs, including minute pirate bugs and assassin bugs, pierce aphids with needle-like mouthparts and drain their fluids. Even toads contribute by eating aphids and other soft-bodied insects near ground level.
Attracting Aphid Predators to Your Garden
The most reliable way to control aphids naturally is to make your garden welcoming to predators that are already in your area. Adult lacewings, hoverflies, and parasitic wasps all need nectar and pollen to survive and reproduce. Planting small-flowered herbs and wildflowers gives them a reason to stay. Dill, cilantro, fennel, yarrow, cosmos, sunflowers, and tansy are all effective choices. Scattering these plants near vulnerable crops creates a habitat where predator populations can build before aphid outbreaks get out of hand.
Avoid broad-spectrum insecticide sprays, even organic ones. They kill the predators along with the aphids, and aphid populations bounce back faster than predator populations do. A garden that looks like it has a moderate aphid problem may actually be a garden where natural enemies are building up to handle it.
Do Store-Bought Ladybugs Work?
You can buy ladybugs by the thousands at garden centers, but managing expectations is important. In research studies, about 95% of released ladybugs flew away within 48 hours, and the rest were gone within four or five days. They’re wild-caught insects with no attachment to your yard.
If you want to try it anyway, a few steps improve your odds. Release them after sunset so they settle in overnight rather than immediately flying toward the light. Mist the plants with water first, since store-bought ladybugs are often dehydrated and will stay longer where there’s moisture. Make sure there’s actually a visible aphid population for them to eat. For roses, the recommended rate is about 1,500 beetles per heavily infested plant, repeated every one to two weeks. Keep any unused beetles refrigerated (not frozen) and mist them lightly to prevent dehydration in storage.
Releasing lacewing eggs or larvae tends to be more effective than ladybugs, since the larvae can’t fly away and have no choice but to hunt aphids on the plants where you place them.