The disadvantages of many insect repellents are that they smell horrid & they are often only effective for a limited time so you can still be bitten in the early hours of the morning. The long-lasting formula of Mosquit-ex is odourless (2&8211;3 minutes after application) & lasts up to 11 hours on one application ensuring night-long protection from mosquitoes & other biting insects. 100ml.