I think the best advice would come from our honoured memebr Andrew Breecher, he has done more hiking kilted in all conditions than anyone else here.
Here is a discussion about it.

I would add my concern about spraying toxic chemicals onto the skin. They absorbed into the blood and may contribute to illness later in life.
I recommend searching for matural repellants.

The kilt is the ultimate outdoor garment imho, I hike a lot in Tasmania. The worst things we get here are leeches, poisonous spiders and snakes.
I find they all run a mile when they see a man in a kilt coming.