When it comes to keeping bugs at bay, there’s no question that DEET is an extremely effective repellent. But it’s not without its drawbacks—and one of them is DEET’s caustic ability to wreak havoc on plastics. And there are two common items of hiking gear that are particularly vulnerable to damage.
The vast majority of sunglasses feature plastic lenses. If you accidentally smear DEET on them and fail to wipe them clean immediately, the DEET will slowly start to eat into the lenses and create permanent damage that can quickly compromise the clarity (and usefulness) of your sunglasses.
2) Plastic maps
Here’s the scenario. You take a break from hiking. Bloodthirsty insects swarm, prompting you to pull out your DEET and apply a layer of protection with your hands. You next use your DEET-coated fingers to grab your plastic trail map, only to discover that the DEET can quickly smear the ink to near illegibility as it chews up the plastic.
So what to do? First, consider using an alternative to DEET such as picaridin, which is widely considered to be as effective as DEET without the plastic-dissolving drawbacks, or oil of lemon eucalyptus, which is the longest lasting natural repellent.
Second, if you do use DEET, keep in mind that you need only a very small amount of it to be effective. There’s no need to slather it on like sunscreen. And if you’ve got it on your hands, do not touch your sunglasses lenses, plastic trail map, or other plastic items.