Don't worry, the title is a bit too dramatic. :)
One would think that with the beginig of summer bonsai work would come to a halt. On the contrary! You have to always maintain your bonsai. For example at this time I had to thin out the foilago on some maples. If I didn't do that, some inner branches could die off, because of lack of light.
Also I had to cut back all the new growth on my conifers.