JW: Mosquitoes, they can really put a damper on your backyard picnic or your camping trip or hike in the woods. Not to mention they can carry diseases. And I think if they are anywhere in my vicinity, they seem to be on a seek and destroy mission. I'm Judy Wagley, this is “From the Ground Up!” Dr. Carl Doud is an entomologist, and director of the Midland County mosquito control. Thanks for joining me today.
CD: Thank you. Thanks for having me.
JW: I understand that in Michigan, we have around 60 species of mosquitoes. Wow, that keeps you busy!
CD: There are-- yes, there are a lot of mosquitoes we have just in our county. We've probably got about 40 species, some of those that occur in the state. And each one of them has got a slightly different biology, a different preference for the type of stagnant water that they prefer-- a different preference for perhaps the season that they're active, and the blood source that they prefer. Some like birds, others, like humans and other mammals, and some may actually even feed on amphibians. And so there's a lot to know about them. There's a lot to get educated about, and in our efforts to try to control those, not only for the well being of the residents in our county, but also because of the potential disease that they could spread.
JW: Yes, and now that Mother Nature seems to really be throwing curveballs at us with the weather-- you know, warmer warms and cooler cools, wetter wets, drier dries, how does that impact mosquitoes?
CD: Largely as you would expect, based on rainfall is the number one factor. There are other things based on the species and the environmental conditions. But the number one thing that really causes us a lot of issues with mosquitoes is the amount of rainfall that you'll get in a season. This season in particular was really actually pretty dry. In the early part of the summer, we went for a number of weeks without any significant rain, but then around the beginning of July, we began getting one rain on top of the other. And what this does is create areas, small pockets of low-lying areas that will hold water, and it's a very good suitable habitat for a number of different mosquito species. So that's the number one factor. There are other things that have occurred; actually, the amount of winter rainfall and snow can have a big impact on the species that come out at the very first of the season. So we'll start seeing larvae in pockets of wooded areas as early as March. And so a lot of that's fed by rains that occur over the winter and the amount of snowfall we get overall.
JW: Well-- this is September and they're still out there! How long can we expect them to still be there?
CD: There are species that will emerge this late in the season, as we get two things: basically sufficient rainfall and temperatures are warm enough to keep them active. And with all of this rain, we're going to have no shortage of mosquitoes that will be present. The only thing that will give us some relief is the cool temperatures setting in. That will go a long ways to bring their activity down and the biting pressure down. And in the meantime, we're doing our control efforts. But when we get the amount of rain across a county, you know, you can't address all of the areas that are producing mosquitoes. So you’ve got to--you know-- just do your best.
JW: Carl, do you have some tips for what folks can do just around their house and their yard, their garden maybe-- some tips for keeping mosquitoes at bay?
CD: The one number one thing is just to remember that any water source that would create anything that can hold water-- and there are a number of types of debris that could be around a home--that can hold water, it's not running water, but just anything as small as a bottle cap. If it holds water, there are mosquitoes that will generally utilize those. It may not be all the species but a few can. So --ensuring that you're tipping out water and you're not letting that go stagnant. For instance, I have chickens and geese at my place. I have to be vigilant about dumping the water that they get if it's not getting drunk down. If it sits for a week or so, I'll have multitudes of mosquito larvae and it's a good organic source. So there's mosquitoes that really look for that kind of a water source. So I have to keep up with that. You might even consider clogged gutters. So, something that you may not see immediately but can produce a source of water. If you get sufficient rain-- then areas, low areas of the yard that that hold water for a week or more can be a site. But the main thing is what you can turn over, if you have rain barrels, try to screen them, cover them up so that mosquitoes can't gain access in there. So that's the number one thing is try to reduce the source of mosquitoes on your own property, if possible. And then the other thing is the forage habits of mosquitoes during the day. So if you are able to keep your yard mowed down, or maybe consider if you've got natural areas that where you want things to grow, and you're going to have a lot of foliage, you know, maybe that could be a little bit further away from your patio. Because not that it produces mosquito in the larval stage--but after they're adults, they're looking for a well-sheltered area with high relative humidity to rest during the day. And then they'll come out in the evenings. So targeting those sites, being aware of that and limiting it on your own property, if that's possible, is an is an another important step that we encourage residents to take to do their own control for themselves.
JW: Those are some great ideas. And I've also heard that some plants including marigolds, lavender and some scented geraniums, are supposed to-- and I'm using air quotes here—“repel” mosquitoes. What are your thoughts on that?
CD: Yeah, well, first off, let me go ahead and plug a couple of really good websites for information because I won't be able to cover everything. The American Mosquito Control Association is a science- based organization, I'm involved with it, as well as the Michigan Mosquito Control Association. If you search for either of those two, and if you have questions, you can find an expert that can answer a question on these issues. What I understand from the studies that have been done, that have looked at various plants that would offer some resistance or repellency to mosquitoes, there have been some studies out there. There are particular repellents that if formulated in a particular way, do offer some significant repellency. But the one thing to caution people is as far as planting things, admittedly, there is not the amount of volatile oils released from a plant that you're going to get from an essential oil that's maybe packaged into a product that is specifically for insect repellency. So whether or not you're going to get significant reduction in mosquitoes in a backyard, because you've planted some of these things like geraniums or marigolds, lemongrass, maybe? Perhaps? But I would just say I haven't seen the data that shows that that step alone would provide a lot of relief. Personal repellents do, in fact, and individuals should look for something that's EPA registered, meaning that they have been screened for both safety as well as efficacy. The EPA requires demonstrating a level of efficacy with personal repellents to be able to get that registration.
JW: If you don't mind me asking a maybe personal question, what do you do to repel mosquitoes?
CD: I am a believer in the all of the repellents--even the ones that are newly developed and introduced. Always used as the gold standard-- their comparison to the active ingredient DEET, which is the most common insect repellent. It's in the OFF products and Cutter and those. It's been around since right at the end of World War Two, and it's got decades of efficacy and safety demonstrated. I go for personal repellents. I think that's the number one best thing you can do. But some people don't care for the scent of DEET. There are good alternatives and I'll just highlight a few. Again, you can find these sources from the American Mosquito Control Association. Or you can contact us at the Michigan Mosquito Control Association. But picaridin is another active ingredient. There's I-R 3535, and oil of lemon eucalyptus has also been demonstrated and in a good formulation sold as a personal repellent. I think any of these four would be a good option for personal protection against mosquitoes.
JW: Well-- many of us need it a lot! Like I mentioned, they seem to be on a mission when they're around me! Dr. Carl Dowd, Director of Mosquito Control for Midland County. We may look forward to the cooler weather. Thanks for all of your information and for Joining me today for “From the Ground Up!”
CD: Thank you so much.
Additional Resources:
