Does Bug Spray Expire? Here's How to Know If Last Year's Repellent Is Still Effective

That's why it helps to have some sort of insect repellent handy to keep mosquitoes, flies, and other unwelcome bugs at bay. If you still have a stray bottle or two at home from last summer, you may be wondering: Does bug spray expire? Though insect repellent may not have a listed expiration date, the summer staple does lose its effectiveness over time. Ahead, we talked to pest experts who answer all our questions about old insect repellent.