I feel mysterious today

Crawling
Over your window you think I'm confused
I'm waiting for the divergent wasp
To complete my current ruse
You use a plate-glass screen
To protect my chosen target
But there's an air-pellet hole
I can crawl through to you
I am the fly in the ointment
I can spread more disease than the fleas
Which nibble away at your window display
Yes I am the fly in the ointment
I shake you down to say please as you
Accept the next dose of disease