When I collect plants, I never treat them for bugs. I put them in a 5 gallon and see what comes out in quarantine. This week I was trying, unsuccessfully, to figure out some Gammarus that appeared. A dragon fly larvae did too, and it went into a water butt that has mosquito larvae. I like dragon flies. But the Gammarus are apart, in a screened greenwater tub. I doubt I'll ever ID them (there are apparently several species around here), but I wanted to see how they'd do, and figured I'd set up a small tank for them when it gets colder.
If they survive the next 2 or 3 weeks, there'll be two of us keeping Gammarus. Funny.
All summer, I had no Daphnia pulex in my cultures, and now with the temperature drop, I have a massive population explosion happening. The ways of small life are mysterious.