A master of eliminating mosquitoes

After covering a long distance, a man got hungry but he had no coin left in his pocket.
Learning that there were a lot of mosquitoes in the village where he was taking a rest, he thought out a way of having a meal. He boasted to the villagers that he was a famous master of eliminating mosquitoes and he had very efficient mosquito-killing pills.
Hearing so, many villagers invited the man to their houses to eliminate the mosquitoes there. The man took the richest villager's invitation. The villager treated the man to a very big dinner and then asked him for the pills. The man took some rice, rolled it into small pills, waved a burning incense stick over them to cast a spell and told the host:
"Whenever a mosquito bites you, please take one of these pills and touch the mosquito with it. If you hit the mosquito with it, the mosquito will certainly die at once."