Outdoor Retailer: How long have mosquitoes, black flies and repellents been the object of your affection?
Merritt: I have been studying black flies and mosquitoes for the past 20 to 25 years. I have been dealing with repellents for the past five to seven years.
OR: How many different types of bug repellent formulations have you tested over the years?
Merritt: I have probably tried 10 to 15 different types of repellents (deet and non-deet based) over the years for control of different biting pests.
OR: Where have you tested these repellents?
Merritt: In Michigan, the Alaskan tundra, and Central and South America, where I was exposed to biting insects during studies in the tropics.
OR: How do you test repellents?
Merritt: You set up controlled experiments in the laboratory, where you put mosquitoes in a cage and then introduce your hand (with and without different repellents) to see the number landing on your hand that start to bite. You then tally the number and look at different treatments. You can do a similar test outside with biting counts or landing counts on your skin, with and without repellents.
OR: Who's crazy enough to submit themselves to these tests?
Merritt: (Silence)
OR: Who's hungry for your research?
Merritt: My research is mainly used to gain knowledge of different products because I receive hundreds of calls every summer from Michigan residents and television and radio stations about biting flies and what to do about them. I would like to recommend something I know a lot about and have tried myself.
OR: It's interesting to note that you work with police officers, helping them solve homicide cases by examining insects found on bodies. When I told other editors, we thought, "Cool, Silence of the Lambs."
Merritt: Yeah (chuckle, chuckle). The movie made us look like pretty big dorks, though. It was those two entomologists trying to hit on Jodie Foster. I always say not all entomologists are sitting in museums playing chess [with pieces] that are insects.
OR: Now, on to the nitty gritty, what ingredients make up most insect repellent formulas?
Merritt: Most repellents containing some amount of deet (the major chemical repellent that works) will give protection. That's the key ingredient in most repellents used today, [besides] inert ingredients like lotion.
OR: What type of nasty bugs does deet repel?
Merritt: Some biting flies, black flies, mosquitoes, some deer flies, biting midges, ticks and gnats.
OR: How does deet work to keep them at bay?
Merritt: Deet disrupts their finding system to the point where they have difficulty lighting and probing and taking a blood meal. And that's usually what they want to do, because they need blood to mature their eggs.
OR: Can you explain how bugs zero in on us?
Merritt: Basically, mosquitoes are attracted to your carbon dioxide (C0). They usually come from down wind, and once they get closer, they pick up the C0 in your breath. Then, the heat given off by your body, in addition to your personal odors, determines how many are attracted to you, and if they'll bite.
OR: Is there anything else that acts like a carrot?
Merritt: If you're sweating, you'll be more attractive. And, certain people are just more attractive because of their personal odors. You'll hear the statement, "Well, mosquitoes just bug me, but my [husband] wasn't bothered at all." It's because her specific odors [i.e. estrogen] are very attractive to mosquitoes.
OR: Is there a rule of thumb for the percentage of deet found in a repellent, depending on what activity it's made for?
Merritt: It's all on a time thing. The higher the dosage [of deet], the longer the time the repellent is protective. Anywhere from 6 percent to 15 percent is fine for gardening or taking a walk in the woods. If you want more protection, like four to six hours, I would go a little bit higher to 20 percent to 75 percent [deet]. (Editor's note: James Heal, research assistant at the Department of Environmental Biology at the University of Guelph in Canada, gives these guidelines: products with 5-percent to 7-percent deet concentration last two hours; 25-percent deet concentration lasts four hours; and 75- percent to 100-percent deet gives six to eight hours protection.)
OR: How many hours of protection does 100-percent deet give?
Merritt: One hundred percent deet gives 10 hours of protection, but I'm not sure if it will give exactly 10 hours; I doubt that. But pretty close?six to eight hours, for sure.
OR: Are you saying that people should leave slight room for error when reading times indicated on the bottle?
Merritt: Yeah, because if you sweat [or are in water], it dilutes [the repellent's potency].
OR: Does sunscreen in repellent formulas affect potency?
Merritt: No.
OR: Does effectiveness vary between brands, say if we compared Off! to Cutters and Ben's, popular repellents used in the outdoor industry?
Merritt: It's all based on the amount of deet it contains. If you tested Ben's 100 with Deep Woods Off! and it was the same percentage of deet, you're not going to find any difference.
OR: If you want a chemical-free formula, what are your options?
Merritt: You can go to something like Bite Blocker, a new insect repellent that uses soybean oils, plant oils, plant extracts and moisturizers, but no deet. It's pretty good. But, it probably won't give you as long a protection time [as a deet-based formula]. (Editor's note: Scientists say that most natural repellent formulations protect for 30 minutes to 60 minutes, depending on ingredients.)
OR: One natural bug repellent, Green Ban's Double Strength Insect Repellent, blends citronella (a chemical-free bug repellent approved by the EPA), lavender, sassafras, peppermint, myrrh and bergamot oils. Are these chemical-free bug repellents effective, in your opinion?
Merritt: Some of these are pretty good, but the only problem is they wear off pretty fast. The odor dissipates a lot faster than deet. And, once the odor is gone, the insects are going to be there. You constantly have to reapply these. (Editor's note: Some companies, such as All Terrain, which produces a natural essential oil-based repellent that lasts up to two hours, have highly potent formulas that, according to studies, are just as effective as low-concentrate deet-based repellents.)
OR: Though you say some natural formulas like Bite Blocker are effective, it sounds like you're partial to deet-based products. Where has it proven effective?
Merritt: We go up to the Arctic research station in Alaska, which is up in the tundra, and you're never there in the summer without mosquitoes?I'm talking 100 per swat.
OR: What about products like Avon's Skin-So-Soft, which isn't registered as a bug repellent, but is used as one?
Merritt: It's not registered as a repellent; it's a bath oil. Its perfumes [repel bugs]. We've tested it in comparison to Off! and it doesn't last anywhere near as long. [However, Avon] now has a new improved formula, which adds more citronella, so it may last longer than it used to.
OR: You said that if people don't want to apply repellents to their skin, they can put it on their clothes, and that's also effective. What if people eat certain foods, like garlic? Does that deter bugs?
Merritt: There's no statistically significant tests showing that if you eat garlic, you'll repel mosquitoes. However, it has worked for some people because you start excreting some of that garlic and the odor repels mosquitoes. My feeling is if it works for you, go with it. But I wouldn't just trust that and take two pounds of garlic into the woods.
OR: Did you also say something about cigar smoke?
Merritt: Yes, one of the best ways to repel mosquitoes when you're fishing is to smoke a cigar because they don't like the smoke. But do you really want to smoke a cigar? Again, it's one of those things, if it works for you, go with it.
OR: With so many variations out there?lotions, sprays, spritzers?do you see a variation in their effectiveness?
Merritt: I don't think there is a difference in effectiveness. It's just a different medium.
OR: Any common mistakes that people make with insect repellents?
Merritt: Yes, it's over-applied. The major cases of repellent poisoning or deet poisoning have generally been with parents who take the top off the bottle and douse their kids with it, instead of reading the instructions. People should follow the instructions. That's the bottom line.
OR: What are common reactions?
Merritt: A rash, or in some cases, it's like a bee sting?some people get a violent reaction. Not too many people I know have gone through that.
OR: How common are allergic reactions?
Merritt: I always use this analogy: If you take 100 people and you give them all Off! to put on, you might have one that is allergic. If you took the same people, and gave them each a glass of orange juice, somebody might also be allergic. It's a natural thing; people are allergic to different products.
OR: Has deet gotten a bad rap?
Merritt: Deet has been in use since World War II and you rarely hear of anyone dying from repellent use. We probably know more about DEET then anything else. Sometimes there's a lot of talk about things people shouldn't worry about that much.
OR: Ever hear of repellents that just don't work?
Merritt: Electric buzzers carried on belts are worthless, and bug zappers are even more worthless. Less than one percent of the insects they attract are mosquitoes. [Instead], they attract more beneficial bugs.
OR: Any other myths out there? I mean other than the myth that all entomologists are geeks?
Merritt: You can put 20 Citronella plants in your house and not do a bit of good. They're not giving off vapors, which is what repels flies.
OR: What about citronella candles?
Merritt: The candles outside in a limited area will work pretty good, if the wind is not blowing 100 miles an hour.
OR: OK, Mr. Bug Man, please tell us, what are some of the meanest, nastiest bugs to get bit by and why?
Merritt: Tabanids (horse flies and deer flies) give the most painful bite as they have cutting and slicing mouth parts and are pool feeders (this means they cut and slice and then lap up the blood); whereas mosquitoes have piercing mouth parts and are vessel feeders. They have an anesthetic in their salivary secretions and pierce a blood vessel with very little pain most of the time.
OR: The worst reaction to a bite?
Merritt: Black fly bites often send both young and older people sensitive to protein to the
hospital.
