We had this happen at work, to the extent we were not allowed the windows open during thunder fly season! I did read somewhere that you can shine a bright light at the side of the laptop in the hope it will head out to the light, or like others have posted, just hope it dies and falls down to the bottom of the screen
Katy -tis me again! - Im ought to go to bed but am bored so thought I would try to be helpful
On googling thunder fly at least 5 of the links are regarding "arghhhhhh I have got one trapped in my laptop!" One person writes that he has 150 - persumably he didnt count each and every one
On you tube there is a vid of one crawling about and this post
"wel here are some tips i googled ! turn of yourscreen foracouple of daysthose bugs hateit when it getcold. plant a hotlamp next to anexit of the screen so theywalktotheheat tip number 2 open paint make a black background with a little whitedot at the right bottom the bug will walk to thewhite dot and then you can﻿ squisheit without fuckin up youre vieuw like me sorry for the crappy english"