With spring also comes insects. Check your supply of fungicides and insecticides. Check your bonsai every day. Don't wait - counterattack at the first sign of infestation. Use a separate bottle for each chemical, and label it.
Preventative measures can be helpful in controlling insects.
The area under your benches should be clean - no leaves, weeds, puddles, etc. Use a commercial insect spray under your benches and along the pathways of your bonsai garden. And, lastly, enjoy.