Ladybugs don’t eat spiders. Spiders are too large, too fast, and too well-defended for ladybugs to prey on. In fact, the relationship usually runs the other direction: spiders are more likely to catch and eat ladybugs than the reverse. However, certain ladybug species are voracious predators of spider mites, which despite their name are not true spiders. That distinction matters if you’re looking for natural pest control in your garden.
What Ladybugs Actually Eat
Most ladybug species are dedicated predators of soft-bodied insects. Their primary diet consists of aphids, and a single ladybug can eat dozens of them in a day. Beyond aphids, ladybugs feed on scale insects, mealybugs, whiteflies, and the eggs and larvae of various small insects. Some species also eat pollen and fungal spores, particularly when prey is scarce.
What all of these food sources have in common is size. Ladybugs target prey that is tiny, slow-moving, and defenseless. An adult spider, even a small one, doesn’t fit that profile. Spiders have fangs, venom, and the ability to move quickly or retreat into webs. A ladybug has no reason or ability to take one on.
The Spider Mite Connection
If you’ve seen claims that ladybugs “eat spiders,” the source of the confusion is likely spider mites. Spider mites are arachnids (related to spiders) but they’re microscopic plant pests, not actual spiders. They cluster on the undersides of leaves, suck plant juices, and leave behind telltale webbing that gives them their name.
A group of tiny ladybugs in the genus Stethorus, commonly called spider mite destroyers, specialize in hunting these pests. At least seven Stethorus species live in the United States, and all of them feed exclusively on spider mites. Adults and larvae each consume up to 75 mites per day. A single larva can devour around 240 spider mites over the course of its development before it pupates. Females need to eat at least 20 spider mites daily just to sustain egg production, according to data from Cornell University’s biological control program.
These ladybugs are small and easy to overlook. Unlike the familiar red-and-black species, spider mite destroyers are tiny, dark, and oval-shaped. They’re most effective once spider mite populations have built up to moderate levels, at which point they move in and can significantly reduce mite numbers. Gardeners and farmers sometimes purchase them as biological pest control.
Spiders Are the Predator, Not the Prey
In encounters between ladybugs and spiders, the ladybug is far more likely to be on the menu. Web-building spiders can trap ladybugs that fly or crawl into their webs, and hunting spiders like crab spiders or jumping spiders occasionally catch them as well.
That said, ladybugs have effective defenses that make many predators, including spiders, think twice. Their bright red or orange coloring serves as a warning signal. When grabbed or squeezed, ladybugs use a defense called reflex bleeding: they release a yellowish, foul-tasting fluid from their leg joints. This fluid contains alkaloid toxins that deter feeding. Both larvae and adult ladybugs can produce it. The combination of bad taste and warning coloration means that many spiders will release a ladybug after the first bite, or avoid them altogether after a previous bad experience.
Using Ladybugs for Garden Pest Control
If you’re dealing with spider mites on your plants, standard ladybug species won’t help much. The common convergent ladybug sold at garden centers targets aphids and similar soft-bodied pests, not mites. For spider mites specifically, you’d want Stethorus species or other mite predators like predatory mites.
For aphid problems, releasing ladybugs can work, but results vary. Ladybugs released into a garden often fly away within a day or two. Releasing them at dusk, after watering plants, and near visible aphid colonies gives them the best reason to stick around. A garden that already attracts ladybugs naturally, with diverse plantings and no broad-spectrum pesticide use, will get more reliable control than one relying on purchased releases alone.
If you’re seeing both spiders and ladybugs in your garden, that’s generally a sign of a healthy ecosystem. Spiders and ladybugs occupy different pest-control niches, with spiders catching flying insects in webs and ladybugs patrolling leaves for aphids. They coexist without much conflict, and both reduce the insect pests that damage your plants.