Wood ants (Formica Rufa) are a large species of ant inhabiting European coniferous forests. The ants themselves are recognisable by their much larger size (some more than 1cm long) than that of the common ant and their impressive nests, which are formed of pine needles normally around the stump of a dead tree, which can be several feet high. These nests can be over 50 years old and smell strongly of vinegar when disturbed. In areas where they are common in summer the woodland floor can be black with ants but they are not harmful to humans although the site can be unnerving. The wood ants are an important part of the eco system and kill many pests and parasites within a pine forest. In some areas of Europe the ants are a protected species. As to their value as 'Bush Tucker' unlike some species of ant from different parts of the world the ants themselves are not edible, but their eggs are. To obtain their eggs lay out a tarpaulin or heavy sheet near the nest and fold the edges over about an inch. Then carefully shovel the entire nest onto the sheet and leave. Instinct will now take over the worker ants will remove the eggs to under the folds of the sheet. When fried the eggs taste like prawns. Another survival use for the woods ants is that if the nest is made around a fallen tree or stump the acid from the ants makes the wood from inside the nest into a cork like substance. This acid treated wood crumbles well and makes excellent material for the early stages of a fire. I would not recommend destroying wood ant nests unless truly necessary, these are marvels of nature and although the ants can rebuild if a nest is heavily damaged the ants will abandon it.
The dark patches in this video clip are actually made up of tens of thousands of wood ants.