Do figs really have dead wasps in them?

If you love figs, you may have heard some unsettling lore about them: that every fig hides a wasp, because these insects need to crawl inside and die in order for the fruit to grow. But are there really wasps in the figs we eat, or is this just a myth?

The answer is somewhere in between. Wasps do play an essential role in the life cycle of many types of fig trees, but most figs from the supermarket are likely bug-free.

Fig wasps are a group of hundreds of species of small insects that spend much of their life inside figs. They're about the size of a fruit fly, and they're not the same type of wasps that sting humans. Figs and fig wasps have evolved alongside each other for millions of years, leading to a special relationship called mutualism, or a link between two species that benefits both of them.

"Fig trees and fig wasps are a great example of a mutualism," Charlotte Jandér, a plant ecology and evolution researcher at Uppsala University in Sweden, told Live Science in an email. "Other examples of mutualisms include trees and the mycorrhizal fungi that help the trees take up nutrients, animals and their gut microbes, and flowering plants and pollinators in general."

In the case of figs and fig wasps, the fruit gets pollinated and the wasp is able to reproduce, leading to a mutualism. But this relationship is rather complex.

What we think of as the fig "fruit" is actually a hollow structure called a syconium filled with tiny flowers. Generally, when a female fig wasp crawls inside a synconium from a female fig tree, she spreads pollen, which the plant needs in order to produce seeds and ripen. The hole that the wasp crawls in is very small, and she may lose her wings and antenna in the process and can even die inside the fig.

So, it's possible that some types of figs may have dead fig wasps inside them.

But that doesn't necessarily mean the figs we eat have wasps inside. Not all types of figs require pollination in order to ripen. Humans eat the fig species Ficus carica, which has several cultivars that are parthenocarpic, meaning they can produce ripe fruit without pollination — and therefore, without fig wasps.

"Most figs we eat in the US have no wasps inside them," Carlos Machado, a biology professor at the University of Maryland, told Live Science in an email.

Mission figs and Brown Turkey figs are two commonly-sold fig cultivars that don't require wasp pollination to ripen and produce seeds, Jandér said. This doesn't apply to all figs that humans eat, though; Smyrna figs, Calimyrna figs, and wild figs around the Mediterranean all rely on wasps for pollination.

"Most wild figs do require pollination to produce ripe fruit," Machado explained. That means these types of figs could have a tiny wasp inside them — but it's still not a guarantee.

Related: How do plants with seedless fruit reproduce?

Just because a wasp was once in the fig, doesn't mean it's still in there by the time the fig is eaten. The synconia of Ficus carcia have a large enough opening that the fig wasp is sometimes able to leave the structure after entering. If the wasp does die inside, her body generally gets squished and decomposes from the process of the fig maturing, Jandér said.

"Even if there were remnants of the original pollinator there you probably would not see them," Jandér explained. Any crunchy texture is more likely from the plant's seeds, not wasp remains.

The fig wasp life cycle

Although wasps sometimes die inside figs, these fruits are actually an essential part of their reproduction cycle. Just as most types of figs need wasp pollination to make new fruit, fig wasps couldn't reproduce without the help of fig trees.

When a female wasp crawls into a fig syconium from a female tree — the type of figs we eat — she only pollinates it, because the flowers inside are too long for her to lay her eggs on. But if she ventures into a synconium from a male tree — which are called caprifigs and generally not eaten by humans — she'll start to lay her eggs.

There, the eggs hatch and develop from larvae into young wasps, which mate while still inside the fruit. Generally, the male wasps die inside the caprifig after mating, though they do help chew a tunnel that allows the female wasps to escape, sometimes even offering themselves as bait for the predatory ants that may be waiting outside. Eventually, the fertilized female wasps burst out in search of a new fig to lay their eggs in, carrying pollen from the old caprifig with them.

There are over 850 species of fig trees, and each one can only be pollinated by a specific species of fig wasp, Jandér said. The relationship between these plants and animals evolved millions of years ago, and both Machado and Jandér pointed to its importance. As a keystone species — an organism that many other plants or animals in the ecosystem rely on to survive — fig trees and their relationship with wasps continue to be of great interest to researchers.

"There are other plant-pollinator mutualisms in nature, but the fig-fig wasp mutualism is possibly the most diverse and most consequential of all," Machado said.