If you've got any product with BT in it, use on your pond with bugs. I had them in
aquariums where I overwinter tropicals, and had good kill using it. They sound like
aphids to me, and yes, they will eat all your leaves. Get rid of them. If there are
fish in there, the BT won't harm them. What I found here to use was granular
mosquito kill that I had bought at Walmart.
Marie