Shannon Amsbery is the Manager of the  Moab Mosquito Abatement District. The goal of the Moab Mosquito Abatement District is to suppress mosquito populations and prevent them from transmitting disease, while having minimal adverse effects on people, wildlife and the environment. The District uses scientifically sound suppression methods in order to serve the ecological and economical long-term best interests of the citizens of Grand County.

Since most mosquitoes lay their eggs in standing water, droughts might seem to reduce mosquito populations, since less water means fewer chances for them to reproduce. But in Moab, that isn’t the case. Climate change has greatly reduced the size of wetlands, killing many of the pests’ natural predators. Now, when the floodwaters do come, mosquitoes reproduce relentlessly. This week, we speak with Shannon Amsberry, manager of Moab Mosquito Abatement, about how his team is keeping the mosquito population under control.

Science Moab: Can you explain why there’s such an overabundance of mosquitoes right now?

Amsberry: When the wetlands were perennially wet, the fish [living there] would eat mosquitoes. But now, the area completely dries out, so when it does flood, there are no predators to eat the larvae. Now, it floods on average every fourth year. But whether the wetlands completely flood or we just get a bit of high water, there are always some mosquitoes.

Science Moab: What are some of the techniques your team uses to take care of the mosquitoes?

Amsberry: We focus on larviciding. It’s better for the environment and the easiest way to keep mosquito populations down. We use a product that affects the mosquitoes’ digestion, which is alkaline-based. It doesn’t affect anything with an acid-based digestion, like people and fish.

Once the mosquitoes are flying, there’s not much you can do. You can’t trap enough mosquitoes to make a dent. If we have to fog [by spraying airborne pesticide over a certain area], we choose very specific places to do the most knockdown, which depends on time of day, the weather, and the wind. Luckily, we don’t have to fog very often; since 2001, we’ve fogged twice, and we were fogging for a West Nile vector.

There’s also an invasive species that we discovered in 2019, the Aedes aegypti. It’s a whole new ballgame. It’s there to eat you; it doesn’t care about birds or mammals. It doesn’t care about the wetlands, it doesn’t care about the river. It likes people. And it wants to live in your backyard. A thimbleful [of water] is all the Aedes aegypti needs to reproduce. An old beer can lands in a ditch? Thousands of mosquitoes will come out of that.

Science Moab: Do these aegypti mosquitoes transmit diseases?

Amsberry: Yes. It transmits Zika virus yellow fever. It’s a very dangerous mosquito. If you’re out in your yard, and you see this rather pretty black and white mosquito flying around, probably trying to bite you on the feet — call me at Mosquito Abatement.

There haven’t been any cases of Zika or yellow fever here, though there are cases of people who’ve gotten it and come to town. We also have very few [cases of West Nile virus].

Science Moab: So, walk me through a day. What does it look like when you’re out there?

Amsberry: We have to wear our waders, and we walk out to wet areas. Most of the mosquitoes are on the edge of these areas. They don’t like deep water. But sometimes that water is hidden underneath dead grass, and you’ve got to go find it. We basically map out where all the water is, and we pay attention to where water comes from.

Science Moab: I remember that 2019 was a really bad year for mosquitoes. Can you explain the situation that year

Amsberry: We were short handed, so we didn’t have anybody able to get out there and get the pesticide down and cover the acres. We had to give up on some areas because they became very rugged and hard to treat. So mosquitoes, when they hatched, could fly right up Mill Creek into town.

I’d walk out my front door and I’d have about 30 mosquitoes land on me within a minute. It was really rough. Because you know, it’s been a long day at work. You come home, you want to relax outside. And you can’t, because even if you’re wearing bug spray, they’re trying to fly up your nose.

Science Moab: Do you have a forecast for 2021?

Amsberry: It doesn’t look like [it’ll flood]. However, anything can happen. It’s the snow that comes down the river in April that’s going to make a difference. If snowpack starts building, we might have a good mosquito year — well, at least good for them.

To learn more and listen to the rest of Shannon Amsberry’s interview, visit sciencemoab.org/radio. This interview has been edited for clarity.