Bonsai Birch tree

[Linda Soffe]

I bought a birch bonsai tree in February this year the leaves came on and it looked really healthy, But the leaves have started to turn brown at the edges and their seem to have little black insects or something underneath each leaf, is their something I can spray it with to kill these nasty thing, that look as if they are killing my lovely tree. I keep the tree outside, I water it well every day and feed it. so please help!!!!

[The Helpful Gardener]

I like neem oil as it's ecologically safe and covers a multitude of sins (fungus, mites, and insects like the aphids it sounds like you have). It is an oil, so no direct sun for a day or so right after you spray, but that should do the trick...