Do Ladybug Spots Tell Their Age? Myths About Ladybird Spots

Why can’t you count a ladybug’s spots to tell its age?

Counting spots is a popular idea with children, but it does not match how ladybugs grow. Like all beetles, a ladybug goes through complete metamorphosis: egg, larva, pupa and adult. The larva grows by molting its skin, but once the adult breaks out of the pupa, it never molts or grows again. Its hard wing cases, and the pattern printed on them, are final.

Lifespan settles the question too. The adults of most ladybugs live up to about a year, and only some survive a second winter. If one spot meant one year, the common 22-spot and 24-spot ladybirds of Europe would be older than almost any pet dog, and every seven-spot ladybug would be exactly seven.

How does a ladybug get its spots?

A freshly emerged ladybug looks nothing like the finished beetle. When it first leaves the pupa, its wing cases are soft and pale yellow, with no spots at all. Over the following hours the colors develop as pigments are laid down in the hardening shell. Black spots come from melanin, the same kind of pigment that darkens human skin and hair. Red, orange and yellow come mostly from carotenoids, the pigments of carrots and tomatoes.

The colors deepen over the next days, and in some species they keep darkening for weeks or months. This is the only real clue to age a ladybug’s color gives: a pale, soft beetle has just emerged. A fully colored beetle could be a few weeks or almost a year old.

Food and temperature can fine-tune the result. Ladybirds that get less food may end up with weaker colors, and in the harlequin ladybird the temperature during the pupal stage can influence how large or dark the spots become. None of this adds spots later in life.

What do the spots really mean?

Spots help identify the species, and many ladybirds are named after their usual spot count. The scientific names follow the same pattern in Latin: bipunctata means two-spotted, septempunctata seven-spotted and vigintiduopunctata twenty-two-spotted. The spots are counted across both wing cases together.

Even within a species the count is not perfectly fixed. A seven-spot almost always has seven spots, but individuals with as few as none or as many as nine have been recorded. The ten-spot ladybird is so variable that many individuals do not have ten spots at all.

Why do ladybugs have spots at all?

The main job of a ladybug’s spots and colors is to warn predators. Red, orange or yellow with black stands out against green leaves and tells birds that the beetle tastes bitter and contains toxic chemicals, as explained in are ladybugs poisonous? A predator that has tasted one ladybug learns to avoid others with similar patterns.

The warning appears to be honest. A 2015 study of five ladybird species found that those that stood out most against their background were generally the most toxic. In some species, colors may also help with camouflage, mate choice or warming up in the sun, because dark surfaces absorb more heat.

Color forms: the two-spot and the harlequin

Some ladybird species come in several distinct color forms controlled by genes. The two-spot ladybird is usually red with two black spots, but black forms with four or six red spots are not rare, and in North America there are even spotless and banded forms. A brood from the same parents can include more than one form.

The harlequin ladybird (Harmonia axyridis), native to eastern Asia and now widespread in Europe and North America, is one of the most variable insects in the world. Its common form, succinea, is orange or red with anywhere from no spots to 22. The conspicua form is black with two red marks, and spectabilis is black with four red marks, and many rarer patterns exist. Color is probably controlled largely by a single gene.

Because harlequins vary so much, spots are a poor way to recognize them. Better clues are their larger size of about 5.5–8.5 mm (0.22–0.33 in), their reddish-brown legs and the white plate behind the head, which often carries a black M- or W-shaped mark.

Other myths about ladybugs

• Myth: Ladybugs are bugs. They are beetles. True bugs, such as aphids and shield bugs, have sucking mouthparts, while ladybugs chew.
• Myth: All ladybugs are red with black spots. Many are yellow, orange, black, brown or cream-spotted, and some have stripes or no markings at all.
• Myth: Every ladybug eats aphids. Some eat scale insects, mildew or leaves, as described in what ladybugs eat.
• Fact: The name honors Mary. “Ladybird” comes from Our Lady, the Virgin Mary, and the seven spots of the seven-spot ladybird were linked to her seven joys and seven sorrows.

So the next time a ladybug lands on your hand, count its spots to learn which species it is, not how old it is.