By Jenny Neyman
Photo by Jenny Neyman, Redoubt Reporter. An adult female mosquito is drawn to exposed flesh by warmth and carbon dioxide, seeking a blood meal with which to lay eggs and complete its life cycle.
Redoubt Reporter
Summer arrived with a vengeance last weekend, with the central Kenai Peninsula’s first memorable occurrence of sustained warmth and shade-worthy brightness so far this season. The sun’s siren call enticed people outdoors in droves to work, recreate or just laze about and enjoy the weather.
But Alaska rarely gives a carrot without some sort of caveat: Abundant run of sockeye salmon? Beware of bears. Midnight sun? You’ll have to create your own dark to sleep. Pleasantly warm weather? Watch out for bugs.
Not that anyone needs to put any particular effort into noticing bugs so far this summer, as mosquitoes are out in droves far thicker than the crowds at even the busiest campgrounds and fishing holes.
“Yeah, they’re thick. I’ve got bites all over me,” said Janice Chumley, integrated pest management specialist at the University of Alaska Fairbanks Cooperative Extension Office on Kalifornsky Beach Road.
“They’re buzzing around me right now,” agreed Dr. David Wartinbee, a biology professor at Kenai Peninsula College. “I would say that they’re pretty aggressive, and there’s lots of them.”
Large, aggressive mosquitoes have hatched in abundance on the Kenai Peninsula, thanks to favorable conditions during the winter.
“It’s because we had a lovely, mild winter,” Chumley said. “All that large amount of snow was the perfect insulating layer. It caused the ground not to freeze very deep, so all the bugs said, ‘Thank you,’ for the large quantities of snow that insulated the ground so well. If you have a deep-enough freeze — if the frost goes deep enough into the ground before it snows enough — it kills the insect larvae and knocks back (the bug population) for a couple of years. But when we have a large snow layer before it gets frozen, then you have a lot of insects.”
Mosquitoes have several strategies for surviving the winter. Some lay eggs in water that hatch come spring thaw. Others hunker down in adult stage and wait out the snow and cold, hiding in a protective environment — such as leaf piles or tree stumps — that help insulate them against plunging temperatures. And mosquitoes can dehydrate their bodies and produce a kind of antifreeze in their blood to stave off the formation of damaging ice crystals.
“They’re pretty good at surviving wintertimes and cold weather by doing one or several combinations of those different things,” Wartinbee said.
Variety also helps ensure the survival of the mosquito population. Alaska is home to great diversity in many arenas of life — think of all the different kinds of mussels and clams to be harvested, berries to be picked and birds to be watched. The same goes for insects. There are more than 26 species of mosquitoes found in the state, Chumley said.
“I had a friend come up here several years ago, a mosquito specialist, and he was excited by the 20-some species he found, but us bug people are kind of goofy. We get excited by strange things — like finding lots of insects — even though we’re getting fed on by these mosquitoes at the time,” Wartinbee said.
Different mosquito species can have slightly different strategies for surviving the winter and thriving in the spring. So no matter what the conditions, at least some of the species will be suited to it. In this case, a mild, snowy winter with a wet spring has apparently been good for several of the larger, particularly bothersome mosquito species.
“You see different species at different times of the year,” Wartinbee said. “It may be that certain groups of them, for whatever reason, had a good winter, were able to survive the cold, had good adaptations that enabled them to survive preferentially, and now are coming out in force.”
Not only was the winter apparently good for many mosquitoes overwintering in adult form, but the abundance of melting snow and rain showers this spring and early summer likely means more new eggs are hatching. Mosquitoes are aquatic insects, after all, spending all but the adult stage of their life cycle in or around water.
“If it’s wet there’re more spaces for them to be found and to hide and to move around. They feed on algae, primarily, so if you have a moist year and there’s lots of water with algae growing in it these guys will go through their life cycle pretty quickly,” Wartinbee said.
Mosquito eggs are laid and hatch into larvae in water. After feeding on algae the larvae form a pupa and emerge into the flying adult mosquito with which we’re all too familiar. As adults, mosquitoes mate, then the females seek a blood meal. So, anyone wanting to be biologically accurate in cursing the buggers ruining their hike or barbecue should use female terminology.
Mosquitoes can lay eggs without a blood meal, but are much more prolific when they do find a tasty mammal on which to gorge.
“If they don’t get a blood meal they won’t produce as many,” Wartinbee said. “Maybe around a hundred eggs or so, and maybe up to 1,000 or more if they do have a blood meal. Some of the other midges will produce several thousand eggs, and I think mosquitoes are probably in that same vein, since the species are closely related.”
(Editor’s note: Wartinbee, when asked, said that the “vein” pun was unintended. That’s, apparently, just how these bug people droll.)
Another mosquito fun fact — adults can be vegetarian if forced, but only reluctantly.
“If you see them sitting on flowers and you’re wondering what they’re doing, they can pick up some sugars from flowers and gain some extra energy so that they can maintain their search for a blood meal,” Wartinbee said.
In the larger scheme of things, mosquitoes are an annoyance of summer in Alaska, but not usually more than that, since mosquitoes this far north are not known for carrying malaria or the other, more-serious concerns of biting bugs at warmer latitudes. Still, a bite is unpleasant and can even be dangerous to those with immune systems that are particularly sensitive to the anticoagulant mosquitoes inject when they feast.
“Everyone reacts differently to different things. We have black flies that bite, we have no-see-ums that bite, and people react differently. Some folks have an allergic reaction to these things and they swell up and itch like crazy. If it gets bad, they should seek medical assistance,” Chumley said.
Though the fate of this being a bad bug year was sealed under the snow this winter, there are steps people can take now to mitigate the annoyance posed by mosquitoes this summer.
- Chumley suggests avoiding mosquitoes as much as possible. Many species tend to be more active at certain times of the day — mornings and evenings, usually — so plan outdoor activities for when mosquitoes are likely to be less active. If camping, hiking, biking, etc., choose rest spots that are away from water, especially standing water. Mosquitoes aren’t good fliers, so they aren’t likely to travel far from where they were hatched. The more dry the environment, the better the chance to escape moisture-loving mosquitoes.
- Take advantage of conditions. Wind can be annoying at times, too, but a breeze can also keep bugs at bay.
- Prepare accordingly.
“You know, that’s what insect repellants are for, and wearing the proper clothing (such as hats, pants and long sleeves),” Chumley said. “And if it gets really bad out hiking, wear bug nets. I know they’re not that much fun to wear, but they are styling, you have to admit. In Alaska we have our own fashion week, where everybody wears Xtratufs and bug nets.”
She doesn’t recommend any particular type or brand of insect repellent, just ones that are research-based. And she advises always following instructions.
“You need to read the label on them, even if it’s very small print. Do not put it on your face, avoid contact with the eyes, your mouth and any of your mucus membranes. It’s easier to apply it on clothing as it is to direct skin. Reading the label is really the best way to get accurate information,” she said.
There are almost as many theories about repelling mosquitoes as there are actual mosquitoes. Some people only bother with repellants with DEET, while others swear by citrus-based products. Some chew garlic, and others advise against wearing anything smelly or perfumed.
It is known for certain that mosquitoes find potential blood meals by honing in on warmth and carbon dioxide. But beyond that, it’s hard to say which avoidance strategies work and which don’t, in part because different mosquito species may be affected somewhat differently, and people, themselves, respond to mosquitoes differently.
“Lots of things work or seem to work for some people and not others. That’s a tough one. There’s just so many variables out there,” Wartinbee said.
Chumley said that people can at least somewhat control their own surroundings to limit mosquitoes. For instance, around a home, residents should make sure to keep standing water at a minimum.
“You can control how much breeding area you have around you. One of the main things people forget about is mosquitoes breed in very little water — even a tire collecting water or a dog dish sitting outside for too long. Every three to five days you need to flush it out to remove the larvae,” she said.
Residents also can make their surrounds attractive to the many natural predators of mosquitoes — like dragonflies, birds and other bugs.
“We have a lot of things that eat mosquitoes, and you want to make your area friendly for them. There are a fair amount of other
Photo by Jenny Neyman, Redoubt Reporter. A golden-crowned sparrow keeps an eye on a mosquito buzzing past its perch. One way to minimize mosquitoes around a home is to attract other creatures, which eat mosquitoes, like dragonflies and many of the area’s songbirds.
insects that eat not just the mosquitoes, but mosquito larvae. Those are the kinds of things that you want to encourage to be around. So if you use something — you spray your entire yard to get rid of mosquitoes — you’re killing the good guys as well as the bad guys. You have to realize that it’s a big food web, it’s not just one thing that’s annoying that we want to get rid of,” Chumley said.
There is still some slim hope that the bugs will bugger off for the remainder of the summer, Wartinbee said, for instance if weather conditions don’t happen to favor the later-arriving mosquito species. But he cautions that finger crossing does about as much good as a mosquito-mitigation strategy as it does a charm to bring sunny weather.
“This group (of mosquitoes) that is around now seems to be pretty abundant, and we’ll see what happens later. They are completing their life cycles now and the larvae are out there feeding, and if it suddenly dries up — if we get a really dry spell here in June and July — that could cause a lot of them that would be harassing us in August to not complete their life cycles,” he said. “So you never know, but predicting that sort of thing is pretty hard because there are so many variables — especially the weather, and you know how good we are at predicting that.”
Science of the Seasons: Summer mosquitoes excel at surviving winter
By Dr. David Wartinbee, for the Redoubt Reporter
There are several dozen species of mosquitoes found in Alaska, and each of them has its own particular life cycle, although all of them are aquatic. Some prefer lakes, others ponds or various marshy habitats. Eggs are laid in the water and hatch out to become “wrigglers,” or larvae. Most of the larvae feed on algae or dead plant materials. They then form a pupa and shortly afterward emerge and become the aerial mosquitoes we love to hate.
The females usually mate and then look for a blood meal — and your arm looks like a great source of that blood. Note that only the females need a blood meal, so those buzzing around your head are all female mosquitoes.
When you and I swat at the mosquito that’s buzzing about, we probably don’t take the time to differentiate the particular species. But each species has its own approach to surviving the Alaska winters.
Many species overwinter as an egg that is laid in water during late summer or early fall. The egg remains underwater in a diapause state of inactivity until spring thaws. In the spring when water temperatures rise, the eggs hatch and the larvae feed voraciously. Within a week or so, they pupate and quickly become the aerial insects we know so well.
Another overwintering approach is for adults to find a safe hiding spot and wait out the cold of winter. Often these hiding spots are within leaf piles on the forest floor, in tree holes or under tree stumps. These areas, especially with a snow cover, provide insulation from the very coldest temperatures of winter.
An important goal for overwintering adults is to prevent ice crystal formation within their hemolymph (insect blood). First they reduce the amount of water in their hemolymph, kind of like concentrating their blood. Then they produce glycerol within the hemolymph, which acts as antifreeze. Now the adult is protected down to some pretty impressive temperatures. This activity is just like what we do to our automobile radiators each winter.
However, if the temperatures around the adult fall below the protected temperature range, the adult will die. Very cold temperatures during a winter with minimal snow cover can reduce the spring population of early mosquitoes.
For overwintering adults, when the ambient temperatures rise in the spring, they are quickly able to leave the hiding place and seek out a blood meal. One particularly large Alaska mosquito uses this overwintering technique so well that it is called the “snow mosquito.” These are usually the first large mosquitoes we see flying around when there is still snow on the ground in early April.
David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the biology of the Kenai River watershed.
