When you think about animals using tools, your mind probably goes straight to chimps using sticks to fish for termites, or crows bending a wire to get a snack.

Maybe you’ve even heard of the octopuses that use coconut shells as armor. But insects?

Probably not. Yet a surprising number of them do use tools, pushing scientists to rethink what tool use actually means. So get out your magnifying glass, because the more we look, the more we find that tool use isn’t rare, but just really, really small. [intro music] First thing’s first: what is a tool and how do we know when an animal is using one?

It’s actually really tricky! Scientists have been debating the exact definition of tool use since at least the 1970s. The main issue is that animal behavior is complex, and it varies between closely related species and even the individual animals within a species.

There’s a thin line between what we’d call tool use and something else, like object use or material use. Like, depending on who you ask, some people might call a bird building a nest out of twigs tool use, while others would say that’s just object use. It’s like when you knit a sweater, the knitting needle is a tool, but the yarn isn’t.

But other scientists counter that nest building is tool use because the nest itself is the tool that the bird makes for shelter and raising babies and stuff. So to keep things simple, we’re defining tool use as the manipulation of external objects to alter the physical properties for a specific benefit to the user. This basically means that the animal actively manipulates something, that is separate from its body, to achieve a goal, whether that’s protection, getting food, or enticing a mate.

Now that we’ve agreed on the rules, it’s Tool Time - insect edition! Our first example is probably something you can relate to. You know the trick where you put your phone in an empty cup to make it sound louder?

Turns out that some crickets do that too, but with leaves! The technical term for this tool is a sound baffle. It’s a structure that increases the intensity of a sound by preventing successive sound waves from interfering with each other.

Oecanthus crickets create their own natural sound baffles by chewing holes in leaves and then pressing their noise-making front wings against the edges of the hole. These baffles can amplify a cricket’s chirps by 8 to 12 decibels, so they pack a punch. Despite how effective baffling is for making noise and therefore finding mates, only about 5% of individuals use baffles.

And that’s no coincidence. Some crickets just don’t need the help. Big crickets, which also have louder calls and very rarely use baffles, have no trouble attracting more mates. females than they know what to do with on a typical night.

But some crickets, often the smaller ones, are quieter and struggle to attract mates. And those are the crickets that will use baffles. With their plant-based enhancements, smaller crickets can turn up the volume of their chirps to match their rivals, and pull in enough dates to keep them busy for the night.

While that last one was all about finding love, this next tool user’s goal is a bit less friendly. These Conomyrma ants really don’t like having neighbors, so they harass any other ants in the area by dropping soil particles, pebbles, and bits of plants down the entrances of rival colonies. Getting used as a garbage dump upsets the rival colonies so much that they almost entirely give up on foraging, and only a fraction of the usual number of workers venture out after these attacks.

Exactly why the siege warfare is so effective isn’t clear, but it’s possible that the stones function as some kind of mechanical signal for the victimized colony to stay underground. By interfering with their competition’s ability to access key resources like food and space, the attacking ants leave more for themselves. And for some species of rock-dropping ants, only some of the ants in the group actually do the throwing.

They’re called sapper ants, and they’re basically the colony’s muscle thugs. Not only do they pelt their neighbours' home with rocks, they also steal food and even attack workers coming out to forage. The existence of sapper ants alongside other castes raises some interesting questions about how different behaviors, including tool use, can appear in groups of nearly genetically identical animals and what that tells us about how tool use evolves.

But ants are industrious creatures, and they don’t just use soil to harass their competition into staying home. Some species from the Myrmicinae subfamily have also figured out a way to transport more food back to their colony. When these ants encounter a pool of soft fruit pulp or some other gooey treat while foraging, they’ll scuttle off to find bits of leaves, dry mud, and small grains of soil.

They’ll toss their selected tool in the food, and wait for up to an hour for it to soak up the tasty goodness like a sponge. With this technique, ants can carry their own body weight in food back to the colony, which is a lot more than they would be able to move by filling up their stomach. And the ants don’t just throw anything that they can find into the food!

They’re actually quite discerning what material they use and seem to consider how absorbent the material is and how easily they can handle it in their mandibles, among other things. When given the chance, ants can learn to use new materials like artificial sponges after some trial and error! Our next two examples really push the limits of how crafty invertebrates can be as they use tools to be more deadly hunters.

While ants seem to have a whole toolbox at their disposal, they’re not the only underground insects that need tools to get the job done. Ammophila wasps don’t live in massive colonies like the yellowjackets you're probably more familiar with. Instead of constructing a paper mâché like nest, female Ammophila wasps burrow into the ground.

They then stock the pantry with a paralyzed caterpillar or several before laying eggs. With her babies well-provisioned for the future, mama wasp covers up the nest with soil and stones. So far, all pretty routine behavior for this type of wasp.

But then the mama wasp does something special to make extra sure that the nest is secure. She’ll grab a pebble with her mandibles and use it like a wasp-sized hammer to compact the dirt on top of her burrow. There are many species of wasps referred to as digger wasps.

Like, it caused us a little bit of headache while fact checking this story to figure out which was which. Of those with this somewhat casual moniker, only a handful of them have been spotted tamping down the dirt in this way, at least according to the sources we could find. No one knows for sure why only some of them do this, but some ideas are that it may have to do with differences in wasp body shape or ecology that led to some species needing a little bit extra help to properly seal their burrows.

Hopefully future research can help us fill in the gaps. and when given the chance ants can learn to use new materials like artificial sponges after a little trial and error now our next two examples really push the limits of how crafty invererbrates can be as they use tools to be more deadly hunters I have to make a little bit of confession. None of the animals we have talked about in this video so far are, scientifically speaking, bugs. See, bugs are actually a specific thing, and are the group of insects with two pairs of wings and biting mouth parts.

Okay, with the pedantic taxonomy lesson out of the way, let’s talk about the bugs that use tools, because it’s pretty weird. Several species of assassin bugs routinely turn themselves into a trap to snare prey. They slather their bodies in sticky resin that they scrape off plants.

The resin has at least two advantages: prey capture and prey luring. A study on assassin bugs from Western Australia found bugs with resin are about twice as likely to land their first strike, and much less likely to have prey escape their clutches, than bugs not using resin. Probably because resin is sticky!

Another species of assassin bug found in Thailand and China goes even further by using resin as bait for angry, and tasty, bees! This assassin bug processes resin by working it with its legs. This seems to make the resin extra stinky by releasing more chemical cues, kinda like when a sommelier swirls wine in a glass.

The assassin’s target, stingless bees, are no strangers to resin either. They also use it as a sticky trap to protect their colony from intruders. When the guard bees smell resin, they think it means that there is an intruder nearby, trying to sneak into the colony.

And when the assassin bug works the resin in its legs, the guard bees come poking around looking for a fight and then wham! The assassin bug gets them! The predator becomes the prey!

Assassin bugs are the big tool users of the insect world: several other species are known to collect resin or sap. An estimated 19% of all insect species that use tools are some type of assassin bug. And as a group, assassin bugs use more tools than every other group of animals except primates and birds!

Why are assassin bugs so handy? Scientists suspect that it’s not so much a case of intelligence as of opportunity. Assassin bugs tend to live in leafy places where their favourite tool of resin is super common, and could even accidentally find its way onto their legs.

Over time, enough assassin bugs could have caught more prey with their accidentally sticky feet to lead a competitive advantage and boom! there you go! we have the beginnings of natural selection at work. Like any other trait, tool use is something that can emerge because everything just happens to be in the right place at the right time. Our last example of tool use comes from a spider, which isn’t an insect.

But there is an insect involved in the story, because these spiders use the insects as tools. Araneus ventricosus, an orb-weaving spider found in Asia, has a taste for a particular species of firefly. Like many fireflies, the males attract females with a sexy pattern of flashes on their abdomen.

They can also communicate to other male fireflies with other patterns of flashing. And our cunning spider exploits this to get a bigger meal. First, it waits for an unlucky male firefly to get caught in its web.

Then the spider does some biological engineering. It bites the firefly, wraps it in silk, and somehow forces it to switch from using his usual female-attracting signal of two flashes to the male-attracting signal of one flash. This false signal draws more male fireflies to the spider’s web!

The spider uses fireflies to catfish it’s prey! Exactly how the spider fiddles with the fireflies’ signals is still a mystery, but some ideas put forward by the researchers suggest that maybe the spider’s venom causes a change in the fireflies brain chemistry, or that it interferes with oxygen supply to the tissues responsible for making the flashes. So while we still don’t know exactly how these spiders work their magic, we’ll just be stuck watching the show along with those trapped fireflies.

From motherly wasps using pebbles as a dirt compactor to hardworking ants that pick and choose their favourite sponge, these tool-using invertebrates expand our understanding of what tool use looks like and who’s capable of it. So keep an close eye on those insects in your tool shed. We don’t want to give them any more ideas. [ OUTRO ]