Sappy Suckers: 10 Neat Things about Aphids
If you garden, you know aphids. They show up like uninvited guests, cluster under your leaves, and start sucking the life out of your plants—literally. But while most of us think of them as pests to squish or spray, aphids lead surprisingly complex lives. They reproduce without mating, get farmed by ants, and leave behind a sticky trail that can turn into a sooty mess. Love them or loathe them, there’s more to aphids than meets the eye.
1. They give birth to live clones.
In summer, many aphid species reproduce asexually through a process called parthenogenesis. The females give birth to living nymphs—no eggs, no mates, and they’re genetic copies of mum.
2. Aphids are born pregnant.
Some aphid nymphs already have developing embryos inside them at birth. This telescoping of generations allows populations to explode almost overnight. It’s a little like how a human baby is born with all of her ova already inside her. So, my mother produced the start (well, half of it) of my daughters, and I produced the very beginning any children they might have.
3. They poop sugar.
Aphids feed on plant sap, which is high in sugar but low in protein, sucking it up through their little needle-like mouths called stylets. They excrete the excess sugar as sticky honeydew, which attracts ants, wasps, and moulds. It’s also the stuff that gets all over your car when you park under a maple tree.
4. Ants farm them.
Ants protect aphids from predators and even herd them to new feeding sites in exchange for that sweet honeydew. Some ants will carry aphid eggs to their nests in winter to “plant” them in spring. And if you shoot the aphids off a plant with a water gun? Ants will carry them back up to get working again! (More about ants.)
5. They can be winged—or not.
When overcrowded or stressed, some aphids develop wings and fly off to colonise new plants. Others remain wingless if conditions are stable and there is plenty of food.Here’s a cool video.
6. Ladybugs love them.
Ladybugs (especially the seven-spotted and two-spotted varieties common in Canada) are natural aphid predators. One adult can eat 50 aphids a day. The larvae, which look kind of like tiny black and orange crocodiles, hover up aphids even faster.
7. They carry plant viruses.
As aphids probe plants with their needle-like mouthparts, they can pick up viruses from one plant and transmit them to another in just seconds, even if they don’t feed for long. This makes them efficient vectors for over 100 different plant viruses, including potato virus Y, cucumber mosaic virus, and bean common mosaic virus—all problematic for Canadian growers. Because the damage often shows up as distorted leaves, mottled foliage, or stunted growth, gardeners may blame poor weather or soil when the real culprit is an aphid-borne infection.
8. Soap really works.
Insecticidal soap kills aphids by breaking down their outer membranes, causing them to dehydrate. You can make your own with a few drops of plain, unscented liquid soap (like castile soap) mixed with water. Don’t use dish soaps that contain degreasers, bleach, or antibacterial agents, because these can burn or damage plants. Spray directly onto the aphids, especially under the leaves, and repeat every few days as needed—it only works on contact.
9. Why wouldn’t you kill aphids?
Not all aphids are villains. Some species feed only on wild plants or weeds and don’t pose a threat to your garden crops or ornamentals. In fact, they’re a vital food source for beneficial insects like—in addition to ladybugs—lacewings, and hoverflies. If you want to support the food chain, you have to have a few aphids. Unless they are doing real damage, maybe hold back on the soap spray.
10. Some aphids are picky eaters, others eat almost anything.
Many aphid species are highly specialized, feeding only on one type of plant or a closely related group. This makes them vulnerable to changes in their host plant’s availability but allows them to be finely adapted. Other species are generalists. The green peach aphid feeds on over 400 plant species, from tomatoes to roses, spreading dozens of plant viruses along the way.
