That's why you need a magnifier, at least 20X,it will let you see the little bugs,and they are little, can be missed with naked eye. Not that you had thrips,you may have burn holes from water droplets on leaves,I have had that happen too.
I got a 420 scope for X-mas, it's 60X to 100X.It's a good tool!my mag was not 20X not near that not even 5x ill have to get a better one for sure.
Yah,I know peoplewho use those,they are fine. I just have the 420 scope because it was a present.radio shack has good dope scopes for about $15.