The World Federation One Stop Fiqh

Ruling 204

If a person kills a mosquito that had sat on his body and the blood sucked by the mosquito comes out of it, that blood is pure – even if the time that elapsed between the sucking of the blood and killing the mosquito was very little – because the blood was in the process of becoming food for the mosquito. However, the recommended precaution is that in this situation, one should avoid the blood [i.e. it is better not to treat it as being pure].