noun
insect bite; bug bite; sting
Refers to the bite or sting itself, or the resulting skin irritation. Covers bites from mosquitoes, fleas, bees, etc.
虫刺されがかゆくてたまらない。
This bug bite is so itchy I can't stand it.
夏は虫刺されに気をつけてください。
Please be careful of insect bites in the summer.
虫除け refers to insect repellent or measures to keep bugs away, while 虫刺され is the bite or sting itself.
Compound of 虫 (mushi, 'insect') and 刺され (sasare, continuative form of 刺される, 'to be stung/bitten').