Mosquitoes were a perpetual problem for devotees. Bhagavan did not criticize the devotees if they swatted mosquitoes which were biting them. In the 1940s, He even permitted the cowshed to be sprayed with pesticides, so that the cows would not be troubled by the biting of mosquitoes or insects. However, if He was questioned about the moral aspect of killing mosquitoes, He would usually answer by saying, that one should not identify with the body, that is being bitten.
A devotee who asked Him about this got the reply:-
‘If you were to take your complaint against mosquitoes to the court of law, the mosquitoes would win the case. Their Dharma i.e the rule that they must live by, is to bite and sting. They live on the blood sucked after biting. They are teaching you that you are not the body. Your object to their stings only because you identify yourself with the body.
(Source: Living by the Words of Bhagavan.)