Red weaver ants live in trees but if there are not enough tree-to-tree aerial routes they will make tracks along the ground to help them forage. However, even here they will use any fallen twig, grass stem or fence wire as an aerial bridge over the ground. They have an aversion and just aren't happy actually on terra firma. Following one of their trails at ground level you can see that it is basically a series of natural bridges over the more awkward, and perhaps dangerous, terrain just below.
I followed one of their routes across a pathway and counted 6 different "bridges" over a one metre distance with the ground only briefly touched twice. A straight line over the ground would have been much shorter but they preferred the aerial zigzag.
As far as I know they only use what they find rather than create bridges but they definitely do get creative with leaves to make their nests. These are constructed out of living leaves in the trees, stuck together using a secretion from their larvae which they use like tubes of glue. These nests can grow to the size of a football.
These guys can be quite vicious biters so I was extremely carefully lying on the ground to take these photos. At ground level they tend to stick to their paths so I just had to make sure I wasn't sprawled across one. If I had been they would have let me know.
They can be a nuisance but many orchard growers value them for the pest control they do even to the point of introducing them into fruit trees where there aren't any.
All these photos were taken in our garden in Thailand where the ants are slowly, slowly spreading...
