Not sure why homemade bug juice instead of commercial, I wonder what his stuff is???
Looks like he had some commercial insect repellant there as well called Nordic Summer
http://www.raymears.com/Bushcraft_Product/284-Insect-Repellent-Nordic-SummerHis home made insect repellant was probably a small bottle of 100% Bog Mrytle essential oil to keep away the dreaded Scottish Midge.
http://www.amphora-retail.com/myrtle-essential-10ml-p-237.html