BLSQ.ORGHow strong are woodants in reality?Abstract
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Ant carrying a lead weight

Abstract: How strong are wood ants in reality?

In the Tilemannschule’s graduation-paper of 1999, there was an article which claimed that ants could carry 30 times their own bodyweight. Since this seemed a little far-fetched, we started researching in specialist literature, but unfortunately, there was no exact data to go with – even scientists are still discussing the maximum weight-bearing capacity of ants. So we started our own project to find out how much our local ant breeds could carry.

In order to do this, we studied different anthills built by different wood ant colonies in the districts of Hadamar, Runkel and Löhnberg. We soon discovered that we had to make distinctions between ‘free carrying’, ‘pulling up free’ and ‘dragging’.

We started collecting a lot of the material the ants were carrying up their hill (concentrating on the items that seemed heavy) and kept them and their carrier in little plastic containers. After cataloguing these samples, we weighed them on an analysis-scale (exact up to 0.1 mg) in the Tilemannschule’s scientific collection.

We then double-checked the results under laboratory-circumstances in a formicary, where the ants were forced to carry the building-material over a board (10 cm high) which served as an obstacle. Even though there weren’t a lot of items to build the nest with, the heavy material was avoided and therefore not used by the ants.

Inspired by similar experiments explained in literature, where little platinum weights were glued on to the ants, we tried to discover the maximum weight-bearing capacity of our local species: We made little leaden weights, which weighed from 30 mg to 430 mg. With slightly dried nail polish, we glued the weights to the backs of our worker ants, which we then let walk over 10 cm of dampened woodchip paper.

In our outdoor studies, we discovered that a worker wood ant could ‘freely carry’ 9.7 times her own bodyweight with her mandibles, without the load touching the ground. A maximum weight of 17.7 times the bodyweight was ‘dragged’ and 7.2 times the bodyweight was ‘pulled up freely’. In our laboratory experiments we could confirm the fact that the ants ‘dragged’ 18.5 times their bodyweight and we determined a weight of 12.2 times the bodyweight when the items were ‘pulled up freely’, while the results for ‘free carrying’ in the formicary did not even come close to those we had in our outdoor studies.

During our capacity-testing, it became clear that, on our testing track, the ants were carrying 30-40 times their own body weight. We trialed several of our worker ants with the maximum burden of 352.9 mg, though not all of them could carry this load. Those who in fact could transport the ‘cargo’ we put on them partly showed significant differences in body weight. Star of our experiment was an ant weighing only 8.9 mg – it therefore carried 39.7 times its own body weight.