Coccinellidae larvae are the immature, wingless stage of ladybugs (lady beetles), and they look nothing like the round, spotted adults most people recognize. They resemble tiny alligators: elongated, dark-colored, six-legged, and covered in bumps and fleshy spines. Most people who encounter them on garden plants have no idea they’re looking at a ladybug, and some mistakenly kill them thinking they’re pests. In reality, these larvae are voracious predators of aphids and other soft-bodied insects.
What Ladybug Larvae Look Like
The typical coccinellidae larva is dark bluish-gray to black, roughly 8 mm (about a third of an inch) long at full size, with a flattened, segmented body tapering toward the tail. Raised bumps called tubercles run along the back and sides, often with branched, fleshy spines projecting from them. Depending on the species, these spines can be black or orange, and many larvae have bright patches of yellow or orange on their abdominal segments.
The multicolored Asian lady beetle larva, one of the most common species in North American gardens, has a mostly black body with bright yellow-orange markings on the top of abdominal segments one through five. This coloring becomes especially vivid in the final larval stage. Convergent lady beetle larvae are similar in shape but tend to have more subdued markings. Across species, the “tiny alligator” body plan is consistent enough that once you’ve learned to spot one, you can recognize most coccinellidae larvae on sight.
Development From Egg to Pupa
Female lady beetles lay anywhere from 20 to over 1,000 eggs during a one- to three-month laying period that begins in spring or early summer. They typically deposit small clusters of yellow-orange, oval eggs on leaves and stems near aphid colonies, giving newly hatched larvae immediate access to food.
After hatching, a larva passes through four increasingly larger stages called instars. Each instar ends with a molt, and the larva grows noticeably between each one. The entire development from egg to adult takes about six weeks during the growing season, though this timeline varies with temperature. Warmer conditions speed development, while cool weather can stretch it out considerably. At the end of the fourth instar, the larva attaches itself to a leaf or stem and pupates. The pupa is small, rounded, and often orange or black. After several days inside the pupal case, the adult beetle emerges.
What They Eat and How Much
The vast majority of coccinellidae larvae are predators, not plant feeders. Their primary prey is aphids, but they also eat mites, thrips, whiteflies, scale insects, small caterpillars, and the eggs of moths and beetles. When aphids are scarce, larvae will supplement with pollen and nectar, though they grow best on a steady diet of live prey.
A single lady beetle can consume as many as 5,000 aphids across its entire lifetime, according to entomologists at the University of Kentucky, and a large share of that feeding happens during the larval stage. Late-instar larvae are especially hungry. Their appetite actually exceeds that of adult beetles on a daily basis, which is why the larval stage is considered the most beneficial period for pest control in gardens and crops. If you see these dark, spiny creatures crawling through an aphid-infested plant, they’re doing exactly the work you want done.
Herbivorous Species to Watch For
Not every coccinellidae larva is a beneficial predator. A small number of species in the family are herbivores, and their larvae feed on plant tissue rather than insects. The Mexican bean beetle is the most well-known example in North America. Its larvae are yellow, covered in branching spines, and feed on the undersides of bean leaves, skeletonizing the foliage. They look distinctly different from predatory species: lighter in color, more uniformly spiny, and found on damaged leaves rather than among aphid colonies. The squash beetle larva is similar. If you’re finding larvae on bean or squash plants and the leaves show feeding damage, you may be looking at one of these pest species rather than a beneficial one.
Attracting and Supporting Larvae in Gardens
Because coccinellidae larvae are such effective predators, many gardeners actively try to encourage them. The most reliable approach is habitat management rather than purchasing and releasing beetles. Lady beetles are highly mobile and will fly away from release sites when prey density is low, which limits the effectiveness of commercial releases. Colorado State University notes that lady beetles are less effective as biological control agents when aphid numbers are low, since the beetles simply disperse to find better food sources elsewhere.
If you do purchase lady beetles for release, place them gently in groups at the base of plants rather than scattering them. Release them in the evening when they’re less likely to fly off immediately, and make sure there’s an active aphid population for them to feed on.
For longer-term results, planting flowers near your crops helps attract lady beetles and gives them supplemental pollen and nectar. Once established adults begin laying eggs in your garden, their larvae will do the heavy lifting of pest control. Any crop attacked by aphids benefits from their presence: vegetables, grain crops, legumes, strawberries, and fruit trees all see reduced aphid damage when coccinellidae populations are healthy. The key is tolerating a small aphid population early in the season so that lady beetles have a reason to stay and reproduce. Spraying insecticides to eliminate every aphid also eliminates the food source that keeps these beneficial larvae around.