Day 22 Pesticide

Can anyone help me? Everything was going well until day 22 with the pesticide. I have been stuck here for so long. No matter how hard I try, I cannot reach the goal. I'm pretty good at keeping the pests at bay now but what do I have to do to reach the goal? Any tips? Thank you.

Yes it a very hard level to beat. I like killing with the mouse. If your mouse is not working very good, it will harder to beat the level. Make sure you have all directx's.