What type of mosquito repellent is most effective?

100% DEET is certainly very effective, but it's hard on your skin. Try it but be prepared to back down to 25% or even 7%.

Some coworker went to a jungle tour in Thailand for 4 days or so. He said not washing and wearing the same clothes for the whole time he was on the tour worked much better for him than all the mosquito repellents the other tourists used :)

True story!

DEET is pretty much the mosquito repellant of choice. The more of it there is, concentration wise, the less pleasant, so scale your concentration based on the risk of mosquito-borne disease.

"Backyard party with friends" - probably a pretty low concentration. "Hell no, I will not be getting malaria while in Uganda" - I used 95% DEET. Stuff was vile, but it worked.

I live in a tropical country with a lot of mosquitoes in some beaches I regularly visit. The best mosquito repellent I know is all natural.

It's vitamin B12. You start to ingest B12 capsules 2 weeks before travelling. Your skin will produce a natural protection with an odour mosquitoes really dislike. It's better than any spray, chemical or citronella candles... cheap and clean! Oh, sure, you can't feel the smell, only the mosquitoes!

I live in French Polynesia (tropical country) and I use monoi. I works very well against mosquitoes, you just have to put more every 3-4 hours. The mosquitoes here really like to bite the feet, especially when I'm working at my desk so I don't bother covering my whole body with monoi, just my feet and ankles.

Mosquitos find their quarry by detecting Carbon Dioxide that is emitted from the pores in the skin as well as breathing and sweating. The reason that Deet, Picardin, or any other repellant works is because it renders the targeted individual "invisible" to the mosquito. Citroenella candles, for example, mask and even combine with CO2, to render an individual or even a group "invisible". Once you understand this simple truth, you will see that by not bathing and not changing clothes you leave the pores in the skin mostly clogged with dirt and oil. This effectively cuts down on the amount of CO2 that you emit and the mosquitos can't find you.