How Big Is The Brain Of A Bee?



Bees may be small, but they are known for being smart.  Bees have been trained to navigate mazes, sniff out bombs and more. 

This may lead use to ask, how big is a bee's brain?  

We measure tiny bee brains by weight, and the answer is, not surprisingly, it depends on the size and species of bee. 

However, from research, we know that:

  • the brain of the honey bee (Apis mellifera) weighs about 2mg; 
  • the brain of bumble bees (Bombus) weigh about 2 - 3mg; and 
  • the brains of large carpenter bees (Xylocopa) are bigger still, weighing about 5 - 7.5mg. 

At the other end of the scale are some of the base-banded furrow bees (Lassioglossum) and the yellow-face bees (Hylaeus), which have brains that weigh less than half a milligram.

Below, this topic is explored in greater detail, looking at the recorded brain sizes of 93 species of bee.

The actual brain of a honey bee.The brain of a honey bee, Apis mellifera
Image after Smith, D., Bernhardt, G., Raine, N. et al. Exploring miniature insect brains using micro-CT scanning techniques. Sci Rep 6, 21768 (2016). https://doi.org/10.1038/srep21768

How Big Is A Bee Brain? 
Which Bee Has The Largest / Smallest Brain?

Unless we measure the brain of every single bee in the world, we cannot be sure which bee has the largest brain, although we could hazard a reasonable guess that the biggest bee brain probably belongs to the world's largest known bee species, Megachile pluto, Wallace's giant bee.   

However, I'm not aware of any research data providing the weight of its brain, and I wouldn't want to hear of any new research in which this species was dissected just to find out - they are rare!

Likewise, the bees with the tiniest brains are quite likely to be the world's smallest bees, currently believed to be Perdita minima and Quasihesma clypearis.

Are bees with larger brains more clever than bees with smaller brains?

This may or may not be true.  For example one study showed that large bumble bee workers are more efficient foragers and are better learners than their smaller sisters.

However, we cannot know for sure whether a bumble bee species with a larger brain than a honey bee, is therefore always smarter (according to the limits of any experiment humans could devise to answer the question).  In fact, there is  plenty of research assessing the ability of honey bees in particular to learn concepts, recognize, remember, among other skills - see Are Bees Smart? 

In comparison, there is little research testing the intelligence of other bees.

In any event, with so many species in the world, we cannot possibly make generalizations and comparisons for all bees, based only on what we know about one species.

What we do know about the size of bee brains...

However, we know the sizes of brains of 93 different bee species, thanks to a piece of research in which this data was collected. 

From that particular study, the smallest was the brain of Lasioglossum sexstrigatum, the Fringed furrow bee, with a brain weighing 0.23mg, and the largest was that of the Carpenter beeXylocopa valga with a brain weighing 7.43mg.

The full tables of data for the 93 bees are provided further down this page, however, it's probably worth summarizing some of the information into key points. 

Largest bee brains

Violet carpenter bee, a large black bee, with an iridescent indigo-violet sheen to the body and wings.  Foraging on a pale lilac scabious flower.Violet carpenter bee Xylocopa violacea - a species with one of the largest brains in the study.

Of the 93 species studied, the top 5 bees with the largest brains were mostly the large carpenter bees, Xylocopa, along with one other species, the Florentine wool carder:

SpeciesCommon NameBrain Size (mg)
Xylocopa valgaCarpenter Bee7.43
Xylocopa violaceaViolet Carpenter Bee5.876
Xylocopa virginicaEastern Carpenter Bee5.438
Xylocopa cantabritaCantabrian Carpenter Bee4.968
Anthidium florentinumFlorentine Wool Carder Bee4.46

However, when we consider the size of the brain in proportion to the body, the White-banded digger bee enters the top 5.

SpeciesCommon
Name
Body Size ITS
(mm)
Brain Size
(mg)
Brain mg /mm
Xylocopa valgaCarpenter Bee7.0247.431.058
Anthidium
florentinum
Florentine Wool Carder Bee4.2544.461.048
Amegilla
quadrifasciata
White-banded digger bee3.8493.9261.020
Xylocopa
virginica
Eastern Carpenter Bee5.5185.4380.986
Xylocopa
violacea
Violet Carpenter Bee6.0955.8760.964

Bee brain size grouped by genus (type)

I grouped some (but not all) of the species by commonly-known type (genus). 

For example, I grouped all of the bumble bees in the study together, and separately, the leafcutters etc, and looked at the range in sizes, just for comparison. (There is some slight rounding of numbers in the table).

Remember the study provided data for 93 species, and whilst this is a lot of bees, there are about 25,000 known species in the world.  Any study can only reasonably provide us with a small snapshot. 

Bee   typeGenusBrain size
range (mg)
Large carpenter beesXylocopa4.97 - 7.43
Bumble beesBombus2.19 - 3.15
Leafcutter beesMegachile1.45 - 2.96
Wool cardersAnthidium1.83 - 4.46
Honey beeApis mellifera1.93
Plaster beesColletes1.84 -1.96
Mason beesOsmia0.58 - 1.94
Mining beesAndrena0.25 - 1.97
End-banded furrow beesLassioglossum0.23 - 0.82
Yellow-face beesHyleaus0.26 - 0.29

The ranked brain size of 93 species of bee

Below are the sizes of brains of all 93 bee species included in the study.

SpeciesSubfamilyBrain Size (mg)
Xylocopa valgaXylocopinae7.43
Xylocopa violaceaXylocopinae5.876
Xylocopa virginicaXylocopinae5.438
Xylocopa cantabritaXylocopinae4.968
Anthidium florentinumMegachilinae4.46
Amegilla quadrifasciataApinae3.926
Anthophora plumipesApinae3.676
Bombus vagansApinae3.147
Bombus fervidusApinae3.066
Megachile pugnataMegachilinae3
Megachile lignisecaMegachilinae2.963
Bombus terrestrisApinae2.823
Bombus impatiensApinae2.821
Bombus pascuorumApinae2.71
Megachile latimanusMegachilinae2.575
Rhodanthidium sticticumMegachilinae2.55
Megachile mendicaMegachilinae2.452
Bombus hortorumApinae2.334
Bombus jonellusApinae2.301
Bombus hypnorumApinae2.29
Anthophora quadrimaculataApinae2.223
Bombus pratorumApinae2.189
Bombus muscorumApinae2.182
Anthidium manicatumMegachilinae2.053
Andrena nitidaAndreninae1.974
Colletes compactusColletinae1.962
Osmia cornutaMegachilinae1.94
Apis melliferaApinae1.927
Colletes simulansColletinae1.839
Megachile mucidaMegachilinae1.839
Anthidium oblongatumMegachilinae1.83
Andrena carantonicaAndreninae1.811
Andrena nigroaeneaAndreninae1.713
Melissodes desponsusApinae1.655
Andrena tibialisAndreninae1.648
Megachile relativaMegachilinae1.635
Andrena cinerariaAndreninae1.633
Panurgus banksianusPanurginae1.63
Melissodes bimaculataApinae1.614
Megachile rotundataMegachilinae1.6
Andrena gravidaAndreninae1.594
Andrena fulvaAndreninae1.591
Eucera elongatulaApinae1.59
Andrena carliniAndreninae1.558
Andrena morioAndreninae1.55
Dasypoda hirtipesDasypodainae1.47
Megachile centuncularisMegachilinae1.449
Andrena flavipesAndreninae1.359
Andrena dunningiAndreninae1.348
Nomada succinctaNomadinae1.34
Osmia bicornisMegachilinae1.241
Andrena variansAndreninae1.17
Andrena haemorrhoaAndreninae1.166
Osmia leaianaMegachilinae1.103
Hoplitis papaverisMegachilinae1.1
Systropha planidensRophitinae0.92
Agapostemon sericeusHalictinae0.855
Osmia caerulescensMegachilinae0.855
Andrena barbilabrisAndreninae0.846
Halictus rubicundusHalictinae0.839
Andrena chrysoscelesAndreninae0.831
Lasioglossum sexnotatumHalictinae0.818
Andrena nigricepsAndreninae0.814
Andrena nubeculaAndreninae0.767
Andrena ovatulaAndreninae0.746
Lasioglossum coriaceumHalictinae0.742
Augochlora puraHalictinae0.734
Andrena simplexAndreninae0.733
Andrena dorsataAndreninae0.718
Andrena bicolorAndreninae0.703
Andrena fucataAndreninae0.701
Lasioglossum zonulumHalictinae0.657
Lasioglossum calceatumHalictinae0.656
Flavipanurgus venustusPanurginae0.62
Halictus ligatusHalictinae0.617
Andrena miserabilisAndreninae0.6
Osmia submicansMegachilinae0.584
Andrena labiataAndreninae0.58
Ceratina calcarataXylocopinae0.502
Panurgus calcaratusPanurginae0.487
Lasioglossum leucozoniumHalictinae0.48
Lasioglossum cressoniiHalictinae0.466
Heriades rubicolaMegachilinae0.42
Halictus confususHalictinae0.418
Stelis breviusculaMegachilinae0.382
Andrena subopacaAndreninae0.343
Lasioglossum fulvicorneHalictinae0.3
Lasioglossum punctatissimumHalictinae0.298
Lasioglossum imitatumHalictinae0.297
Hylaeus modestusHylaeinae0.287
Hylaeus mesillaeHylaeinae0.26
Andrena semilaevisAndreninae0.254
Lasioglossum sexstrigatumHalictinae0.231


The ranked brains size of 93 species of bee, in proportion to body size by ITS

The rankings of bee brains change a little, when we consider the size of the brain in proportion to the body.

SpeciesSubfamilyBody Size ITS (mm)Brain Size (mg)Brain mg /mm
Xylocopa valgaXylocopinae7.0247.431.058
Anthidium florentinumMegachilinae4.2544.461.048
Amegilla quadrifasciataApinae3.8493.9261.020
Xylocopa virginicaXylocopinae5.5185.4380.986
Xylocopa violaceaXylocopinae6.0955.8760.964
Xylocopa cantabritaXylocopinae5.3784.9680.924
Anthophora plumipesApinae4.083.6760.901
Rhodanthidium sticticumMegachilinae3.2722.550.779
Megachile lignisecaMegachilinae3.92.9630.760
Megachile pugnataMegachilinae4.0830.735
Bombus fervidusApinae4.23.0660.730
Megachile latimanusMegachilinae3.5712.5750.721
Anthidium manicatumMegachilinae2.8742.0530.714
Andrena nitidaAndreninae2.8081.9740.703
Colletes compactusColletinae2.8141.9620.697
Colletes simulansColletinae2.661.8390.691
Panurgus banksianusPanurginae2.3791.630.685
Bombus hypnorumApinae3.372.290.680
Bombus pascuorumApinae3.9952.710.678
Bombus impatiensApinae4.1842.8210.674
Bombus vagansApinae4.6963.1470.670
Andrena carantonicaAndreninae2.7751.8110.653
Nomada succinctaNomadinae2.0571.340.651
Bombus terrestrisApinae4.3512.8230.649
Bombus hortorumApinae3.652.3340.639
Apis melliferaApinae3.0181.9270.639
Melissodes desponsusApinae2.6041.6550.636
Bombus pratorumApinae3.4972.1890.626
Megachile mendicaMegachilinae4.012.4520.611
Andrena gravidaAndreninae2.6351.5940.605
Melissodes bimaculataApinae2.6721.6140.604
Andrena cinerariaAndreninae2.7241.6330.599
Anthidium oblongatumMegachilinae3.1151.830.587
Megachile mucidaMegachilinae3.1641.8390.581
Andrena fulvaAndreninae2.761.5910.576
Anthophora quadrimaculataApinae3.862.2230.576
Andrena carliniAndreninae2.7121.5580.574
Bombus jonellusApinae4.0182.3010.573
Bombus muscorumApinae3.8122.1820.572
Megachile rotundataMegachilinae2.861.60.559
Eucera elongatulaApinae2.8461.590.559
Megachile relativaMegachilinae2.9631.6350.552
Osmia cornutaMegachilinae3.6311.940.534
Andrena morioAndreninae3.041.550.510
Andrena tibialisAndreninae3.271.6480.504
Dasypoda hirtipesDasypodainae2.9571.470.497
Hoplitis papaverisMegachilinae2.2131.10.497
Andrena dunningiAndreninae2.7841.3480.484
Andrena nigroaeneaAndreninae3.5731.7130.479
Andrena haemorrhoaAndreninae2.4361.1660.479
Andrena variansAndreninae2.521.170.464
Andrena flavipesAndreninae2.9281.3590.464
Andrena nubeculaAndreninae1.7090.7670.449
Andrena chrysoscelesAndreninae1.8530.8310.448
Megachile centuncularisMegachilinae3.4021.4490.426
Osmia leaianaMegachilinae2.7661.1030.399
Osmia bicornisMegachilinae3.1721.2410.391
Lasioglossum coriaceumHalictinae1.9050.7420.390
Systropha planidensRophitinae2.4050.920.383
Augochlora puraHalictinae1.9540.7340.376
Andrena barbilabrisAndreninae2.2920.8460.369
Halictus rubicundusHalictinae2.3140.8390.363
Lasioglossum calceatumHalictinae1.8920.6560.347
Agapostemon sericeusHalictinae2.4770.8550.345
Panurgus calcaratusPanurginae1.4160.4870.344
Flavipanurgus venustusPanurginae1.8740.620.331
Lasioglossum sexnotatumHalictinae2.560.8180.320
Andrena bicolorAndreninae2.2050.7030.319
Andrena dorsataAndreninae2.2620.7180.317
Andrena nigricepsAndreninae2.620.8140.311
Andrena miserabilisAndreninae1.9570.60.307
Andrena simplexAndreninae2.3910.7330.307
Osmia caerulescensMegachilinae2.80.8550.305
Lasioglossum zonulumHalictinae2.2850.6570.288
Halictus ligatusHalictinae2.1890.6170.282
Osmia submicansMegachilinae2.0790.5840.281
Andrena ovatulaAndreninae2.6930.7460.277
Andrena fucataAndreninae2.660.7010.264
Andrena labiataAndreninae2.2330.580.260
Ceratina calcarataXylocopinae1.9530.5020.257
Heriades rubicolaMegachilinae1.6420.420.256
Halictus confususHalictinae1.6810.4180.249
Lasioglossum fulvicorneHalictinae1.260.30.238
Lasioglossum cressoniiHalictinae20.4660.233
Lasioglossum leucozoniumHalictinae2.2170.480.217
Lasioglossum imitatumHalictinae1.4780.2970.201
Lasioglossum punctatissimumHalictinae1.5630.2980.191
Stelis breviusculaMegachilinae2.020.3820.189
Hylaeus modestusHylaeinae1.530.2870.188
Hylaeus mesillaeHylaeinae1.40.260.186
Andrena subopacaAndreninae1.8470.3430.186
Lasioglossum sexstrigatumHalictinae1.260.2310.183
Andrena semilaevisAndreninae1.640.2540.155

Note:  ITS = Intertegular span.  The distance between where the wings attach on the body. This measurement has been used as an estimate of bee body size and expected flight abilities (Cane 1987).










Resources

  • Sayol, Ferran et al. (2020), Data from: Feeding specialisation and longer generation time are associated with relatively larger brains in bees.
  • Engle C., Baum K., Can You Bee-lieve it? The Intertegular Span of Bees, Howard Hughes Medical Institute.
  • Mares S, Ash L, Gronenberg W. Brain allometry in bumblebee and honey bee workers. Brain Behav Evol. 2005;66(1):50-61. doi: 10.1159/000085047. Epub 2005 Apr 8. PMID: 15821348.








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