It wasn't easy to draw detailed enough foliage for fairies to believably have been hiding in it, without it still obscuring the fairies. You still kinda have to look twice.
I can imagine how tricky that must have been. I was able to spot them without too much trouble, and as you said, the fairies are meant to blend in so they could be hidden until needed.
I won't have the false modesty to pretend that my background art didn't improve radically in the course of this comic, but I'm still learning it.
Right now I'm at the step of balancing background detail VS things that are about as large as said details but should stand out more.
The fairies emerging in the last panel look great. There's just enough black to contrast them against the background while still looking a bit camouflaged.
I really enjoy your background work, especially the woodland scenes. It is constantly excellent.
And they prove themselves! Resourceful trolls, they are!
Given the fairies' reaction, they might have been better off looking useless...