Is it obligatory to change clothes and bathe every time after using the lavatory to relieve oneself if impure insects have landed on one's clothes, given the inability to ascertain the exact location of the impurity?

The majority of jurists are of the opinion that slight impurities which are difficult to guard against, such as the traces of flies or mosquitoes, are forgivable. This is because meticulously avoiding them would impose hardship on people, and Allah Almighty says: "And He has not placed upon you in religion any difficulty."