What Is the Smartest Insect? What Bees, Ants and Flies Can Do

On the evidence we found, the smartest insect is the honeybee, though no study ranks insects on one test. Honeybees count up to four landmarks, treat zero as less than one, and learned to add or subtract one in lab tests. Smart depends on what you measure. A honeybee brain holds fewer than a million cells, and a fruit fly's holds 139,255 neurons. The question of the smartest bug asks the same thing.

The new finding is how little brain these results need. In 2018 Howard and colleagues reported that honeybees order zero below one, an understanding they compare with African grey parrots, nonhuman primates and preschool children. Below: what each insect did in the lab, how many cells their brains hold, and why neither list gives one winner.

What is the smartest insect?

The honeybee has the strongest evidence of any insect we reviewed, across counting, zero, arithmetic and concept learning. Bumblebees, ants and fruit flies each have their own best-known results. Here are the lab results behind that pick, each from a different task.

• Counting: Dacke and Srinivasan (Animal Cognition, 2008) trained honeybees to fly past a set number of landmarks to reach food. The bees counted up to four, even with new objects, and the count was mainly sequential
• Zero: Howard and colleagues (Science, 2018) trained individual honeybees to choose the group with more or fewer elements. Bees then extended less than to zero, ordering an empty set below one
• Adding and subtracting: Howard and colleagues (Science Advances, 2019) taught honeybees to use blue and yellow as symbols for addition or subtraction. Bees then solved unfamiliar problems of adding or subtracting one element
• Same and different: Giurfa and colleagues (Nature, 2001) found that honeybees learned matching and non-matching rules and carried them over to new stimuli, even in another sense
• Moving a ball: Loukola and colleagues (Science, 2017) showed that bumblebees that watched a live or model demonstrator learned to move a ball to a target more efficiently than bees that saw none, and then used the ball closest to the target instead of copying the long route

Each result is a strong finding about those bees on that task. None puts bees on a scale with other insects. Our smartest animals study shows how the winner changes with the yardstick when many species are compared, and the same lesson applies here.

How do you define the smartest insect?

You pick a yardstick first, and the answer follows from it. Three yardsticks are in use for the smartest insects, and they rank insects differently.

• Brain size: the number of cells in the brain. The honeybee has more than the desert ant and the fruit fly, on the figures below
• Lab tests: what an animal learns when researchers train it. Honeybees lead on number and concept tasks, bumblebees on ball and string tasks
• Wild skills: how an insect navigates, teaches or builds. Desert ants and tandem-running ants stand out, though these studies use different tasks again

A fourth yardstick, an IQ, does not exist for insects. An IQ needs a norm group of thousands of members of one species taking the same test. Our IQ bell curve shows what that number means for people.

How many brain cells does an insect have?

Fewer than a million in the honeybee, desert ant and fruit fly counted here, and the total depends on the method. Godfrey, Swartzlander and Gronenberg (Proceedings of the Royal Society B, 2021) estimated brain cell numbers in 32 species of Hymenoptera, the group that includes bees, wasps and ants. They counted all cells, neurons and glia together.

• Honeybee: about 613,000 cells by their count of nuclei (standard deviation 128,000). An older estimate from brain sections was about 850,000
• Desert ant (Novomessor): about 90,000 cells by brain sections and about 70,200 by nuclei counts
• Fruit fly: about 92,500 cells by brain sections and about 88,300 by nuclei counts
• Fruit fly by wiring diagram: 139,255 neurons, from the FlyWire reconstruction of an adult female brain (Dorkenwald and colleagues, Nature, 2024)

The last two lines show the catch. Two methods put the fruit fly's brain near 90,000 cells, and the wiring diagram found 139,255 neurons. Counts depend on what is counted and how, so treat each total as a rough size, not a score. For comparison, a pigeon's forebrain holds 83 million neurons, in our article on the smartest bird in the world.

Can a brain with fewer than a million cells be smart?

In narrow ways, yes. Howard and colleagues (Science Advances, 2019) write that advanced numerical cognition may be more accessible to nonhuman animals than previously suspected, and their bees showed it with a miniature brain. Small brains can hold rules, as the sameness and difference result shows.

That does not make a bee clever in the human sense. A rule learned over many trials, for a food reward, is not the same as a plan made in one go. For a bigger brain facing a choice puzzle, see our article on the Monty Hall problem and what pigeons did.

Are ants smarter than bees?

The evidence does not decide it, and ants have the smaller brains. Godfrey and colleagues found that ants stand out from bees and wasps as having particularly small brains, by mass and by cell number.

Ants still do clever things. Desert ants gauge how far they have walked by counting steps: ants walking on stilts overestimated the distance they had travelled, and ants on stumps underestimated it (Wittlinger, Wehner and Wolf, Science, 2006). In Temnothorax ants, Franks and Richardson (Nature, 2006) described tandem running as teaching, which they said was, to their knowledge, the first teaching shown in a non-human animal. These are skills in different species on different tasks, so they do not rank ants against bees.

Is a clever insect result always a sign of insight?

No. Researchers often find that a simple learning rule explains a skill that looks clever. Alem and colleagues (PLOS Biology, 2016) taught bumblebees to pull a string for a reward. The skill spread through a colony, but the bees failed a coiled-string test, and the authors say the learning needed no insight.

That caution applies to every item above. A result tells us what the animal can do, not why. It also usually comes from one species, a few trained animals and one narrow task, which is how a leader in one lab can look very different in another.

What about the smartest bug?

Most people who ask for the smartest bug, or what is the smartest insect, mean a common insect, so the honeybee answer above covers them. In everyday speech, bug also takes in spiders and centipedes, which are not insects, and we did not review them.

If you want a number for yourself, take the IQ test and read it against the bell curve. Our guides to the octopus, another small-bodied animal with a big reputation, and to brain size and IQ show how little size alone tells us.

Common questions