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Everytime I see a ladybug I ask myself this question. Why does every ladybug have a different amount of points on its back? Is it because of its age? Or because of its genes? Is it inheritable?

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  • $\begingroup$ It is unclear if you are asking about variation in the number of spots within or between ladybug species (so intra- or interspecific variation). $\endgroup$ – fileunderwater Nov 2 '15 at 21:35
  • $\begingroup$ I am working on a children's book with a group of friends about a bug named Willow. For this book, we have needed to do research on ladybugs and how they get their spots. Ladybug spots do not tell you the age of a ladybug, but they can tell you the species. Some ladybugs don't even have spots. The most common ladybug is the Coccinella septempunctata or seven-spotted ladybug. $\endgroup$ – joe Nov 4 '17 at 1:47
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The spots on the back of Ladybugs over the surface is defense mechanism to avoid predators. The spots come in different shapes and different numbers. Some say that those dots tell us their age. Since some ladybugs have 24 spots which means its age would be 24 years and that is not at all possible. So this is a popular misconception running around us.

But the real truth about the number of spots on the ladybugs' back is:

The number of spots on a ladybug does have significance. The spots and other markings do help you identify the species of ladybug. Some species have no spots at all. The record-holder for most spots is the 24-spot ladybug ( Subcoccinella 24-punctata), which has 24 spots, of course. Ladybugs aren't always red with black spots, either. The twice-stabbed ladybug ( Chilocorus stigma) is black with two red spots.

So now we know that the number of spots on the back of Ladybugs will help us to identify what species it belongs to. To give an insight into different species of them you can refer to this Identifying Ladybugs.

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The above image shows different species of Ladybugs where you can see the varying number of spots in each bugs' back. More information can be found here Stripes on Ladybugs.

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    $\begingroup$ If I am not mistaken there is also intra-species variation in the number and mainly shape of the points. $\endgroup$ – Remi.b Nov 2 '15 at 21:06
  • $\begingroup$ Though this is a good answer describing how we can use spots for ladybug ID, it doesn't actually answer the OP's question: "WHY do they have multiple spots?" I'm surprised the OP accepted this answer... $\endgroup$ – theforestecologist Jan 9 '16 at 19:20
  • $\begingroup$ Yes, some species like the harlequin ladybeetle (Harmonia axyridis) can have dozens of different morphs, with different number of points. $\endgroup$ – Kjian Apr 23 at 14:55
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It is because of genes, and is completely inheritable! First I want point out that there spots, or points, do not change over time. Rather the spot number and location is fixed when Coccinellidae are pupa (tween aged insects).

You will notice I said Coccinellidae instead of ladybug. That is because "ladybugs" are actually several different species of insect. Thus we refer to the whole family of ladybugs, Coccinellidae. The spot number, shape, and color is different for different species, which gives you the variation in the number of points.

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