A group of French tourists, while crossing Africa by car, noticed that those drinking Artemisia annua tea where less attacked by the fierce mosquitoes of this continent than those relying on the standard pharmaceutical pills.
It is well known that mosquitoes are attracted more by some people than by others. People in Southern countries have often noticed that the brunt of mosquito attack is on foreigners because “their blood is so sweet”. Could it be that what we eat or drink has an influence? Some believe that the best repellent is bitter blood. It is even claimed that he efficacy of well known commercial repellents like DEET is probably due more to gustatory than to olfactory sensors (JL Sanford et al., Naturwissenschaften, 2013, 100-3). And DEET is very bitter. Another paper has shown that bitter substances are deterrents which inhibit the mosquito feeding on sucrose solutions. This is particularly the case for the bitter quinine (S Kessler et al., J Exp Biol, 2013, 1292-1306).
So quinine may have protected Europeans during the colonial period from mosquito bites.
All Artemisia plants are very bitter, not so much by the artemisinin content, but by a vast array of bitter substances which might exudate with the sweat.
In fact most of the medicinal plants are bitter and it is known that this favours digestion and bioavailability of food and drugs.