Almost every time I pass a forest route with swamps or rocky rivers, I come across this little robber.
Exactly! That is the robber fly! I think it's a pretty cool common name for a member of the family Asilidae. And it appears that different species of robber flies live in such an environment. That is very possible because areas adjacent to rivers or swamps typically have an abundance of feed, and most predators hunt their prey there.
Despite the fact that robber flies lack jaws, they are one of the most feared predators of other insects. The robber fly's main weapon for stabbing its prey is a pointed proboscis. They also have powerful legs with razor-sharp claws.
This one is a species of Ommatius, a genus of robber flies with the smallest body size of any Asilidae member.
All of the images here are my own work, taken with a Xiaomi POCO NFC smartphone and an assembled external macro lens.