A close-up photo of a mosquito.
Photo: Jamie Chung/Trunk Archive

The number of insect-borne diseases is increasing, according to the Centers for Disease Control and Prevention. And the number of places they're spreading to is also on the rise. A report from last year showed that reported cases of tick- and mosquito-borne diseases more than tripled between 2004 and 2016.

This includes familiar diseases like the mosquito-borne West Nile virus and tick-borne Lyme disease, as well as some lesser-known ones such as the Powassan virus and Tularemia, which are both spread by tick bites. In fact, the CDC reported that since 2004, nine new mosquito and tick-borne diseases have been discovered in the U.S. and its territories. And there’s always the possibility that previously obscure diseases, like Zika, could re-emerge as widespread threats.

“We need to continue growing our arsenal for controlling mosquitoes and ticks at the community level,” says Benjamin Haynes, a CDC spokesman. “And personal protection will always be most important.”

A key component of personal protection is insect repellents. The good news is that there are a lot of insect repellent formats to choose from, such as sprays, lotions, and wipes, and they contain a range of active ingredients—that is, the ingredients that make the repellents work.

But these products are not equally effective.  

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“There’s a mind-boggling number of choices that you have to make,” says Joe Conlon, a former Navy entomologist and technical adviser to the American Mosquito Control Association. “And it’s actually very important to pick the right product because it will be your best defense against some very serious diseases.”

That’s where Consumer Reports comes in. We’ve added several new products to our ratings this year—including a number of products marketed as family-friendly or natural—to give you the best possible sense of what matters most when you're buying an insect repellent for you and your family.

And our testing paints a clear picture: Whatever the form of the repellent, whether a spray, wipe, or lotion, products made with the active ingredient deet, in concentrations of 25 to 30 percent, have proven most consistently to provide high levels of protection against biting bugs.

Here, five of our top-rated repellents (the full ratings are online here).

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What CR's Tests Found

Twelve of our 15 recommended insect repellents use deet as their active ingredient. Two are made with 20 percent picaridin, and one contains 30 percent oil of lemon eucalyptus (OLE). Most "natural" products we’ve tested, including several containing citronella oil, peppermint oil, soybean oil, or others, have performed poorly.

Our ratings are primarily based on how long a product protected test subjects against mosquitoes. Our highest-rated ones protected for 6.5 hours or longer; our lowest-rated ones lasted 2 hours or less. We currently test repellents only against mosquitoes, but in past years of testing we’ve found that repellents that worked well against mosquitoes also worked well against ticks. We also test for how well the product resisted causing damage to materials that repellents are likely to come into contact with, like fabric, paint, and nail polish.

Our testing suggests that when it comes to effectiveness, what matters most isn’t the brand name or whether it’s a lotion, spray, or wipe, but rather the type and concentration of active ingredient in the repellent.

For example, two wipes (Repel Insect Repellent Mosquito Wipes 30% Deet and Off Deep Woods Insect Repellent Towelettes), a store-brand spray (Total Home Woodland Scent, sold by CVS), and a lotion (Sawyer Ultra 30 Insect Repellent), have all made our recommended list. All contain deet.

Consumers should note: There’s one key pattern that has continued to appear year after year in our insect repellent testing. While we’ve found some sprays using the active ingredients picaridin or OLE that performed well, deet-based products consistently earn most of our top scores.

And among the lotions and wipes, only those containing deet were found to be highly effective. In a few instances in previous years of testing, we’ve found products containing 20 percent picaridin scored well as a spray but not in another form, such as a wipe or lotion.

"We expect that differences in formulation, and how the active ingredient is incorporated into a repellent, can make a large difference in how effectively it repels insects,” says Joan Muratore, test project leader for insect repellents for CR. “However, among the products we’ve tested, we have found deet, at levels of 25 to 30 percent, to afford the most reliable protection against mosquitoes and ticks."  

'Natural' Is Not More Effective

Each year, we add new insect repellents to our ratings, which already include repellents tested in previous years that are still being sold.

Market analysts at the research firm Mintel found that 56 percent of consumers believe natural pest control products (including insect repellents) are just as effective as conventional ones. So for this year’s tests, we evaluated six new products, half of which don't contain deet.

Unfortunately, our testing shows that “deet-free” isn’t generally a good thing. These products don’t usually perform as well as those containing deet. The products we’ve tested whose active ingredients are essential oils all earned a rating of “Poor” for protection against mosquitoes.

We’ve also found that products with higher concentrations of deet protect for longer periods of time than those with lower concentrations. Although products with more than 30 percent deet are available to consumers, we’ve found that those with 25 to 30 percent provide long-lasting protection. Consumer Reports doesn’t test products with more than 30 percent deet for this reason—for good results, it’s unnecessary to expose yourself to higher concentrations.

If you do want to avoid deet, two deet-free repellents we’ve evaluated in past years of testing have earned our recommendation: Repel Lemon Eucalyptus Insect Repellent2 (which contains 30 percent oil of lemon eucalyptus) and Sawyer Premium Insect Repellent 20% Picaridin.

But it’s also important to remember that despite consumer concerns, the Environmental Protection Agency says that deet, when used properly, “does not present a health concern to the general population.” The agency has performed extensive reviews of the potential harms of deet, and found that the risk, when it’s used properly, is minor. The agency estimates that seizures linked to deet may occur in about 1 in 100 million applications of the substance, for example. (Your chances of being struck by lightning in a given year are about 100 times greater.)

How We Test Insect Repellents

In our insect repellent testing lab, a testing day begins with applying a standard dose of repellent to a measured area of skin on our test subjects’ arms. The standard dose is determined from the EPA product testing guidelines.

After 30 minutes, these brave volunteers then place their arms into the first of two cages of 200 disease-free mosquitoes for 5 minutes. Our testers watch closely to see what happens inside the cage, and they count up every time a mosquito lands on a subject’s arm, uses its proboscis (its long mouth) to probe the skin in an attempt to find a capillary, or bites the subject’s arm and begins to feed—which the testers can tell by watching for the insect’s abdomen to turn from grey to red or brown.

After five minutes, the subjects withdraw their arms, then repeat the process by placing their arms into a second cage of disease-free mosquitoes of a different species, for another five minutes. The subjects then walk around for 10 minutes, to stimulate sweating—this is to mimic a real-world setting, in which users might exercise while wearing repellent.

Half an hour later, this procedure is repeated once, and then again once every hour after that until a repellent fails our test, or until 8 hours have passed since it was applied. We consider a failure to be two confirmed mosquito bites in one 5-minute session inside the cage, or one confirmed bite in each of two consecutive 5-minute sessions.

How to Apply Insect Repellent Properly

For best results, follow the directions on the label and these five tips:

1. Apply a thin coat to all exposed skin, but avoid eyes and mouth, and use sparingly around your ears. You can also spray repellent on top of your clothing, but do not apply under clothing.

2. Adults should dispense repellent on their hands to apply to children. Don’t spray repellent onto kids or apply to their hands to avoid it getting into their eyes or mouth, and avoid applying to cuts or irritated skin. (Insect repellents with deet should not be used on children younger than 2 months.)

3. Frequent reapplication isn’t necessary. Wash hands after applying and wash off repellent at the end of the day.

4. Never spray directly onto the face. Spray on palms, then apply to the face.

5. When using towelettes, be sure to use enough of them to cover all exposed skin with repellent.

Jeneen Interlandi and Catherine Roberts contributed reporting to this article.

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