Yikes! Apparently this factoid is true:
"Ants are arguably the greatest success story in the history of
terrestrial metazoa. On average, ants monopolize 15-20% of the
terrestrial animal biomass, and in tropical regions where ants are
especially abundant, they monopolize 25% or more."
Proceedings of the National Academy of Sciences of the United States
of America: In search of ant ancestors
"According to Hölldobler and Wilson (1990), up to 1/3 (33%) of the
terrestrial animal biomass (NOTE: not including aquatic animal, or
terrestrial and aquatic flowering plants and microorganisms) was made
up of ants and termites. A study made in Finland produced a
terrestrial animal biomass of ants alone of 10%. In the Brazilian
rain forest the biomass of ants exceeds that of terrestrial
vertebrates by four times! Thus a figure for ants of 15% of all
terrestrial animal biomass is not out of line. I would doubt that they
are 15% of all living things because plants and microorganisms make up
a large part of the earth's biomass and the biomass of marine
organisms (none of which are ants) is usually not included in such
Hölldobler, Bert, and E. O. Wilson. 1990. The Ants. Harvard University
Press, Cambridge, Massachusetts.
LaSalle, J., and I. D. Gauld. 1993. Hymenoptera and Biodiversity. C.A.B.
International, Oxon, U.K."
Mad Scientist Network: Percentage of biomass made up by ants
"Ants are everywhere on earth. When combined, all ants in the world
weigh about as much as all humans (Hölldobler & Wilson 1994)...
Hölldobler B. & Wilson E. O. (1994). Journey to the Ants. Belknap
Press, Cambridge, Massachusetts."
Shinshu University: Effects of food rewards offered by ant-plant
Macaranga on the colony size of ants
This Pulitzer Prize-winning book by Hölldobler and Wilson is often
cited as the definitive study of ants. It appears to be the main
source of the estimates of ants' biomass which appear all over the
Amazon: The Ants
My Google search strategy:
Google Web Search: biomass ants mammals OR humans
Google Scholar: biomass ants mammals OR humans
Thanks for an interesting (if creepy) question, Monroe. I'm starting
to think that if I want to guarantee my success in the future, I may
want to look into aphid farming. On the other hand, I am discomfited
by the fact that not only do ants outweigh humans, but so do a couple
other kinds of critters. Termites, krill, and squid are often
"The biomass of the human population is substantial, but not the
greatest. Antarctic Krill accounts for 2-5 the biomass of humans, and
all species of both squid and termites exceed human biomass."
Brain Off: Emergent Decision Making in Modern Virtual Societies
Calamari, here I come!