Something getting hungry ?

[Moonshine123]

Hi all hope you’s are all keeping well.

 

Have 9 seedlings here around 2 weeks old and the noticed past day or two that there is something nibbling my leaves. They are like wee slices on the leaves. Only two of them are infected so far, but haven’t seen any bugs or any sign off bugs even.
 

Before they went into tent I even disinfected it really well and give everything a good rub down (never had a problem before just like being safe and clean) 
 

What could it be? Don’t understand how, whatever it is, got in to the tent? 
 

Anyway I’ve got 3 bug bombs here that I have never used, want to know the proper way to use them? Do I set it off in the tent or the room the tent is in? Also do I do it when lights are off and turn off all extractions etc 

 

thanks for help folks