it can, and if oyu choose to use it, vege is the time.. don't ever use that crap in bloom. i have some for major problems... i'm not a pest expert though... i do know what poison is.
outside, so not sure how much DE would help (diatomacous earth)... probably just blow away. not useful wet for these purposes. natural pest killer (food grade will say it is not a pesticide, but that's the only one you should use like this... do not use filter grade as that's poison too, lol)