The 411 on Bug Repellents

 Photo by galitskaya / Adobe Stock

One type does not fit all!

You’re at your cabin throwing some things into a backpack for a day hike: water bottle, trail mix, sunscreen, trail map, GPS unit and insect repellent. But what kind of bug blocker? Some people have very strong opinions about their choice of insect repellent. And that's fair–one type does not fit all. How do you decide which one is right for you? 

Why you need it

First of all, insect repellents are necessary to help ward off mosquitoes and ticks that can transmit harmful diseases in the U.S. Mosquitoes can transmit West Nile virus, while ticks can transmit diseases like Lyme, babesiosis, anaplasmosis, Rocky Mountain spotted fever, tularemia, Southern Tick-Associated Rash Illness and ehrlichiosis.

Choosing the right repellent

If you want protection against both mosquitoes and ticks, the Centers for Disease Control and Prevention (CDC) recommends that you use a repellent that contains 20% or more DEET. For protection against just skeeters, the CDC suggests repellents with one of the following active ingredients:

DEET

N,N-Diethyl-meta-toluamide was developed in the 1940s and 1950s by the U.S. Department of Agriculture and the U.S. Army. Originally, the most popular form was 100% pure, but these days most people prefer lower concentrations. Brands containing DEET include Off!, Cutter, Sawyer and Ultrathon. According to the American Academy of Pediatrics (AAP): Don’t use DEET on infants less than 2 months old, and don’t use concentrations higher than 30% on children of any age. And that goes for everyone, because, as the AAP points out, “DEET greater than 30% doesn’t offer any additional protection.”

Picaridin

Available in the U.S. since 2005, picaridin is structurally based on chemicals found in pepper. Products that contain it include Cutter Advanced and Skin So Soft Bug Guard Plus. A repellent with 20% picaridin has been shown to repel mosquitoes for 8–10 hours.

Oil of lemon eucalyptus (OLE)

Brands containing OLE include Coleman Botanicals and Repel. A recent Consumer Reports study found five repellents containing OLE were effective for 7-plus hours. However, the CDC does not recommend it for children under 3 years old.

IR3535

In case you are wondering, the chemical name for this ingredient is 3-[N-Butyl-N-acetyl]-aminopropionic acid, ethyl ester. It’s a synthesized plant oil developed in the mid-1970s by Merck. Coleman Skin Smart is one product that contains it. According to a U.S. Environmental Protection Agency (EPA) study, IR3535-based products provide 8 hours of protection against mosquitoes. And contrary to the CDC’s recommendation that only DEET protects against skeeters and ticks, an EPA study found that at least two IR3535-based products also provided 8 hours of protection against ticks. Currently, there are no health warnings about IR3535 from the EPA or AAP.

Permethrin

You can also consider wearing socks, pants and boots treated with permethrin, which is a synthetic repellent modeled after naturally occurring pyrethrin from flowers. You can buy clothing right off the rack that contains permethrin or you can treat your clothes yourself. Outdoor stores like REI sell permethrin in spray bottle form. When choosing the correct repellent for you, keep in mind that all products are not created equal. You need to know which insect you’re trying to avoid and how long you’ll be outdoors, according to the EPA. The agency recommends: “Look for EPA-registered products that provide protection time information on the product label.” Just don’t get hung up on protection times. “A shorter protection time does not mean the product is less effective,” warns the EPA. You may just need to reapply a repellent with a shorter protection time if you’re going to be outdoors for a long period.

Furthermore, you may need to reapply bug repellent based on other factors:

• Physical activity

• Level of perspiration

• Water exposure

• Air temperature

• How attractive you are to ticks and skeeters (or as grandma used to say “how sweet you are”)

Using bug repellent safely

It’s important to monitor the concentration of certain repellents and be careful when applying them to children. REI offers these tips:

• Avoid under- and over-application of repellents.

• Always follow the instructions on the label.

• When using spays or aerosols, avoid inhaling spray or mist.

And for DEET, REI cautions:

• Read and follow all directions and precautions on the label of the product.

• Do not apply over cuts, wounds or irritated skin.

• Do not apply to hands or near eyes and mouth of young children.

• Do not allow young children to apply this product.

• Use just enough repellent to cover exposed skin and/or clothing.

• Do not use it under clothing.

• After returning indoors, wash treated skin with soap and water.

• Wash treated clothing before wearing it again. Note: DEET is capable of dissolving plastics and nylon.

• Use may cause skin reactions in rare cases.

• When using sprays or aerosols, do not spray in enclosed areas; to apply to face, spray on hands first and then rub on face. Do not spray directly onto face. Wash hands afterwards.

   

A Better Mosquito Repellent

It may not be long before we have better weapons for battling mosquitos. Scientists at the University of California, Riverside (UCR) and Vanderbilt University (VU) published research in October 2013 and May 2011, respectively, that may eventually deliver safer and stronger alternatives to DEET. The research is focused on the insect’s sense of smell. Whereas mammals have olfactory receptors (OR) on the surface of nerve cells in their noses, mosquitos’ ORs line their antennae. Scientists studied the ORs and how they react to specific chemicals, like DEET. They reached new insights, and the results are promising:

• UCR researchers identified three safe compounds that mimic DEET. The compounds don’t dissolve plastics and may be affordable to produce in large quantities, great for developing countries where people suffer from insect-transmitted diseases.

• VU scientists discovered a new class of insect repellent, a compound named Vanderbilt University Allosteric Agonist (VUAA1) that may be thousands of times stronger than DEET.

What Else Can You Do?

 No repellent is 100% effective. So other than buying the right kind for you and applying it correctly, here’s what else you can do to prevent bug bites. 

1. Cover up. Wear pants, long sleeves and closed shoes when possible, especially when venturing into tick- and mosquito-infested areas. Before you venture into tick territory (high grasses or heavy brush), tuck your pants into your socks, and tuck your shirt in.

2. Hike in the center of trails.

3. Check your hiking gear and your pets for ticks upon reentering the cabin.

4. Avoid the outdoors during peak mosquito time, early morning and evening.

5. Check your window screens for holes and repair them.

6. Reduce mosquito habitat by eliminating standing water (open rain barrels, bird baths, wading pools, etc.).

7. Check yourself for ticks every night.

8. Reduce tick habitat by cutting back on shaded areas around your cabin.