Ladybugs are one of the most beloved beneficial insects in the garden, though most people, including many gardeners, only recognize adult ladybugs.
That’s understandable — immature ladybugs look nothing like their adult forms — but it’s important to get to know ladybugs during all stages of their life cycle so beneficials aren’t confused for pests. In fact, while ladybugs are well-known to devour aphids, ladybug larvae are more voracious than the adults, eating hundreds of aphids before pupating.
Another important thing to know about ladybugs — which entomologists prefer to call “lady beetles” — is that they are not bugs at all. Bugs are members of the order Hemiptera, while ladybugs fall under the order Coleoptera, the order that all beetles belong to. A beetle goes through a complete metamorphosis between its larval phase and reaching its adult stage, also known as its imago, while an immature true bug is called a nymph and already resembles its adult form.
The iconic ladybug look is red with black spots, like the North American native nine-spotted ladybug (Coccinella novemnotata) and the European native seven-spotted ladybug (Coccinella septempunctata), but ladybugs come in all sorts of color combinations. They can be yellow, orange, gray, black and even blue, with spots or stripes. The multicolored Asian lady beetle (Harmonia axyridis) has so much diversity in its colors and spot counts that one of its common names is harlequin, which means “in varied colors.”
Both the seven-spotted ladybird and the multicolored Asian lady beetle have been introduced to the United States for pest control. While effective at reducing aphid populations, they pose an ecological problem because they outcompete native North American ladybugs. The three species all look alike during their larval stages, so trying to root out non-natives while they are immature can be an insurmountable task.
Not every ladybug species is carnivorous. The ladybug family, Coccinellidae, also includes the subfamily Epilachninae, the plant-eating ladybugs. The squash ladybug, or squash beetle, (Epilachna borealis) is a garden pest that attacks the vines, leaves and rinds of squash, pumpkins, melons, and cucumbers, and the Mexican bean beetle (Epilachna varivestis) feeds on legumes. The good news for gardeners is that in the larval stage —when they are yellow with long black spikes — no one would mistake these pests for beneficial ladybug larvae.
Whether you call them ladybugs, ladybirds (the preferred name in the U.K.) or lady beetles, here’s what gardeners need to know about this insect’s life cycle.
Predatory ladybugs lay clusters of anywhere from five to 30 eggs on the underside of a leaf near a food source — such as an aphid colony. The eggs are yellow or orange, oval-shaped and stand on end.
You may spot the ladybug eggs on milkweed with an oleander aphid infestation. When the eggs hatch in two to 10 days, the larvae will get to work eating the aphids.
Beneficial ladybug larvae look like little black alligators with orange spots or stripes. They have six black legs and start out so small that they are easy to miss. On a steady diet of aphids, scale and mites, they will quickly advance through four instars. Three weeks to a month after they hatched, they will be ready to pupate.
When a larva prepares to pupate, it hunkers down on a leaf and holds on. It molts its black, spiky skin as it begins to take the shape of an adult ladybug. It goes from black with orange spots to yellow or red with black spots, and undergoes metamorphosis over the course of one to two weeks.
When an adult ladybug emerges from the pupa, it takes a few minutes to get acclimated to its new form and spreads its wings — the first time in its lifecycle that it can fly. A newly minted adult will have a soft yellow exoskeleton that soon hardens and turns into the ladybug’s permanent color. The adults can live for up to a year, overwintering someplace out of the elements.
I hope you have gained a great understanding of the ladybug life cycle and how to identify beneficial ladybugs at all stages of their growth. Do you attract ladybugs to your garden for pest control? Let us know in the comments below.
Links & Resources
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