Ecology is hard

When I downloaded this photograph, I noticed that there is alot going on in it.

I have taken a few photos of wetland plants for identification purposes, and I keyed this little floating plant (well, the larger one of the two…. I think the smaller one is either Lemna aequinactialis or Spirodela polyrhiza [Duckweed]) to Limnobium laevigatum.  After I keyed it out, I noticed the aphids or other sucking bug, and then I noticed the fly in the upper left.  It was hard enough to key the one plant out… now I have two plants in one picture, potentially competing, a herbivore concentrated on one plant, and another spectating insect that could itself and/or its larva be a predator on the herbivore!limnobium-laevigatum-05102009-092514