Vagrant darter (Sympetrum vulgatum) is the last dragonfly in the air, flying as late as in October. In a sunny weather, you can see a whole group of them flying around a suitable hill.
The male is red in colour, while the female has a darker colouring. The species is common in Finland. The first larvae hatch in July and stay in their larvae stage for a year. The larva enjoys all kinds of still water, and you can try to see if you can spot them at the bottom of the water.