The specter of Zika might have faded from the headlines, but insect repellents will remain a key staple of summer safety for the foreseeable future.

The number of insect-borne diseases, and the geographic areas to which they can spread, are increasing, according to the Centers for Disease Control and Prevention. That includes familiar diseases like West Nile and Lyme, and some lesser-known ones such as Powassan.

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

The good news is that there are a lot of repellents to choose from, including sprays and lotions, brand names and store brands, and a range of “active ingredients”—that is, the ingredients that make the repellents work.

The bad news is that not all of these products are equally effective. And as the list of choices expands, it can be tough to know what to pay attention to. Do lotions work as well as sprays? Are store brands as good as brand names? Is the active ingredient the most important factor in deciding how safe or effective a product is?

More on Insect Repellents

“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 (AMCA). “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 a range of new products to our ratings this season—including our first-ever tests of repellent lotions and store-brand repellents—to give you the clearest possible sense of what matters most in the bug-spray aisle.

Our ratings are primarily based on how long a product protected test subjects against mosquitoes. 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 highest-rated ones protected for 6.5 hours or more; our lowest-rated ones lasted 2 hours or less. In our tests, repellents that worked against mosquitoes also worked well against ticks.  

Overall, we found that the type and concentration of active ingredient were the common denominators in the products that worked best as well as in those that did poorly.

For example, among the nine products that earned our “recommended” status, there are only three active ingredients: deet, picaridin, and oil of lemon eucalyptus (OLE). (Most natural products we’ve tested, including several containing soybean oil, have done poorly.) 

A store brand (Total Home Woodland Scent, made by CVS) and a lotion (Sawyer Ultra 30 Insect Repellent), which both contain deet, made our recommended list. That suggests that when it comes to effectiveness, what matters most isn’t the brand name or whether it’s a lotion or spray, but rather the type and concentration of active ingredient.

But we found one instance where this wasn’t the case. The Sawyer Picaridin Insect Repellent lotion (which contains 20 percent picaridin) didn’t perform nearly as well in our testing as the Sawyer Premium Insect Repellent 20 Percent Picaridin spray, which was top-rated by Consumer Reports last year and continues to be recommended. The Sawyer picaridin spray provided 7 hours of protection, but the Sawyer picaridin lotion worked for less than an hour.

Sawyer suggests that this discrepancy stems from the amount of repellent we used in our testing. The company said that people naturally apply about one and a half times as much lotion as we applied to our test subjects, and at that higher dose, picaridin lotion is actually one of the longest-lasting products on the market.

“Sawyer stands by the effectiveness and longevity claims on our product,” said a Sawyer spokesman, Travis Avery. “Picaridin insect repellent has been used worldwide since 1998 and is one of the best-selling active ingredients.”

Consumer Reports tests all insect repellents by applying the same amount of each product to our test subjects to ensure a fair and comparative playing field.

The Environmental Protection Agency doesn’t require that companies that make repellents tell consumers exactly how much to apply—and Sawyer’s label doesn’t give specific application instructions (nor do any other repellent products we tested). But Conlon and other experts on repellents we spoke with said that consumers shouldn’t have to use more of any one product than another. “You should use just enough to cover your skin,” Conlon says. “That amount should be enough for any product to work as advertised.”