Bugs are small, except for the ones that aren’t. But luckily, we’re not dealing in the realm of bugs that are too big to properly squish. We’re dealing in the realm of bugs you probably squish if you happen to turn your head in the wrong direction. If you thought the smallest bug would still be visible to the naked eye, you might want to think again. With that in mind, what is the smallest bug–and how small is it, really?
Oh, and if you thought we were going to go down the whole “there are tiny mites and lice all over you all the time” angle, also think again. For starters, mites are arachnids and bugs are technically insects. But in case you were wondering, the smallest mites are around 82 micrometers long. Smaller than the insects we’re going to be talking about.
Further Reading: What’s the Difference Between Bugs and Insects?
The Smallest Bug
So technically bugs and insects are two different things, even though we use them almost synonymously in daily life. Bugs are a more specific classification of insects, they’re all within the order Hemiptera. Anything in that taxonomic order is classified as a “true bug.” We’re talking about the smallest “true bugs” first because it’s actually far less exciting than the smallest insect.
There’s an entire infraorder of bugs known as Dipsocoromorpha, which are just a bunch of really small bugs. Normally they just hang around leaf litter (hence why some call them litter bugs), though they can also be found near streams and mangroves in tropical regions. We actually don’t know too much about bugs under the Dipsocoromorpha banner, even their fossil record poorly preserved to the point where we know they existed as far back as the Early Cretaceous period but not exactly where they fit in in the grand bug map.
The infraorder contains a handful of families, though because research on these buggers comparatively sparse, those families will probably shift around.
What we really need to know to answer the question is how small Dipsocoromorpha gets, and that’s around 0.5 millimeters (mm). We can get smaller.
Here’s a dig on Dipsocoromorpha, as small as they are–that’s their only remotely impressive feat. Except there exists an insect that is not only leagues smaller, but can also fly. Get out of here litterbugs, you share a name with one of the most universally hated things another person can do.
Also pick up your trash.
Unfortunately, fairyflies aren’t actually flies. Or fairies, but you probably knew that. Fairyflies are actually a family of wasp. How small are fairyflies? Well the smallest among the fairyflies is also the smallest known insect. It’s Dicopomorpha echmepterygis, coming in at 0.139 mm long. The smallest known flying insect is also under this banner, but they’re a little bigger at 0.15 mm long. Which means they’re smaller than some single-celled organisms.
It’s no joke that fairyflies push the boundaries of how small insects can get–they’re so small their wings look more like some stringy hairs on a stick. You might think that this wouldn’t be an effective form of locomotion, but fairyflies are so small that air is almost like molasses to them. They float through the air like you can tread water with your hands. Because they’re so small, they forgo traditional insect circulatory systems, and can rely more on breathing just by… Passively existing. It’s called diffusion and it’s more complicated, but it’s just as passive.
Males of Dicopomorpha echmepterygis just gave up on eyeballs and even mouths altogether. Even larger fairyflies have super underdeveloped eyes anyway. As far as mouths go, that’s not new for insects, the large Atlas moth also has no mouth as an adult.
Of course, because they’re wasps and wasps are awful, fairyflies also rely on parasitoid techniques to get even smaller. Reproducing is expensive, and eggs require a lot of yolk and just stuff to get life going. Those are resources fairyflies can’t afford, especially since they’re already throwing away the nuclei in their cells. So fairyflies lay their eggs inside other insect eggs, so some other sucker ends up doing the work producing yolk for them.
We liked it better when fairies were magical and not tiny parasitoid monster wasps.
Let’s just think about fairy tales instead here.