The Ohr Somayach publication on the Daf Yomi [Weekly Daf (#209)] stated that harmful creatures sometimes serve the purpose of punishing the wicked. The example given was the Roman Emperor Titus who destroyed the Beis Hamikdash. Hashem punished him, causing a mosquito to enter his nose and creep into his brain. It tortured him for seven years until he died.
But why do good people need the mosquito around? Why does the mosquito harm me, when I haven't harmed anyone? When my daughter was in Israel this past summer, she spent one night sleeping outdoors in the desert; the mosquitoes practically ate her up.
It's dangerous to sleep unprotected in the desert. Creatures deadlier than mosquitoes live there: Snakes and scorpions, for example. The temperature, too, can drop drastically in the desert at night. With no cloud cover, nothing to block high winds, etc., a person can go to sleep comfortably and wake up dead from hypothermia.
The mosquito incident will probably discourage your daughter from sleeping unprotected in the desert on a continual basis, and thus protect her against these dangers. Looked at this way, mosquitoes can be seen as squadrons of "health police" who save people's lives with their vigilant patrol. In moister climates, mosquitoes keep people from sleeping outside in the summer on the wet grass, hence protecting them against potentially fatal sicknesses such as pneumonia.
When Adam ate from the Tree of Knowledge of Good and Evil, he caused an almost irreversible mixture of Good and Evil. Since then, you can always find something good and something bad in anything you look at. The Torah believes that an underlying good pervades everything, and it's up to us to seek the good, do the good, and look for the good in everything. [For more on this subject, see Public Domain below]
- Rabbi Avigdor Miller
- Rabbi Zev Leff