Some may find the following chemical weapon against the 'Bugs' useful, along with Neem, Tea tree oil and Citronella there is another natural insect repellent called bog myrtle,

http://www.stopbite.com/

Might be useful for those if nothing else seems to work. The Vikings apparently used it as an insect repellent. Its was also put into ancient traditional heather beer brews. The beer is available today, I had a couple of Pints during the week from the local supermarket. The Vikings used to drink the brew before going into battle with their customary berserk frenzy. A bit like MREs