Developed in 1946, DEET has been used extensively since then and serves as the standard mosquito repellent against which new candidate materials are tested. In addition to working on mosquitoes, it works well on fleas, biting midges (punkies, no-see-ums) and black flies.

Yes, DEET does repel midges, but its effectiveness can be somewhat hit-or-miss compared to its performance against mosquitoes. Midges (especially the infamous Scottish "Highland Midge") are tiny and can be extremely persistent. While a 20% to 30% DEET concentration will discourage them from biting, many travelers in 2026 find that Picaridin (like Smidge) or IR3535 are actually more pleasant and effective for midge-heavy areas because they don't have the oily texture or chemical smell of DEET. Another popular 2026 alternative is "Dry Oil" sprays (like Avon Skin So Soft), which many locals swear by, as the oil physically traps the midges. If you use DEET, remember it can damage plastics (like sunglasses frames), so apply it carefully to your skin and avoid getting it on your gear.