What id actually do is go to a pond. There are loads! Ive taken some entomology courses which require us to collect a certain number of insects and then identify them so the last one i took was introduction to aquatic insects. What i would do, is go to walmart or something and buy a little kids butterfly net, or a pool net with a deep mesh net for leaves since actual entomology nets cost and arm and a leg and just go to a pond and run the net through the water a couple of times and you will be surprised at whats in there! Predacious diving beetles swim very fast and some do bite so careful . Is there a specific species that your friend was looking for?
They didnt say :/ i can find out though. I dont even know what they need them for lol they just sent me a message on FB asking if i knew wear to get them lol i can ask. Gimme a bit and ill get back to you when i get a message back They will be happy to know though the pond is a great place.