More Mosquito Murmurs…

I recently posted about ways to stop mosquito bites from itching, and primarily what doesn’t work. Big H and I were talking the other day and he had recently read (heard?) that mosquitoes buzz around your head because it gets you agitated and brings your blood to the surface (sorry for the simplified retelling, Big H!). I told him I thought it was because mosquitoes find their prey by sensing carbon dioxide.

Big H went on to say he wouldn’t want to do the research on that, which I think meant he didn’t want to be the guy with the mosquitoes buzzing around his head. I have done the research, though, and wrote this little essay about mosquitoes and a (abbreviated) trip I took into the Wind River Range with my friend Jill and my ex-dog, Baty:

The best blood will at some time get into a fool or a mosquito.
–Austin O’Malley

Baty’s snout was swollen with mosquito bites. The little insects crawled over his nose, paws, and lower legs—the spots where his Malamute fur was a bit thin. I slapped a few away from him, and my dog’s blood smeared across my fingers. Bumps grew on the normally tight skin of the ridge above his nose. Baty was miserable and I felt guilty for bringing him somewhere that brought him such discomfort. I had included him on this ten day backpacking trip because he loves hiking, but I didn’t count on this. My first trip into the Wind River Range was supposed to be an introduction to the beauty and magnificence of this place, but it turned out to be a lesson in preparedness.

Baty and I had been up since five that second morning of our trip; that’s when the mosquitoes started attacking him again after a short night’s reprieve. When I awoke at sunrise, I peeked through the netting of my bivy sack and saw the insects swarming Baty, oblivious to the paw he kept running over his nose. I slipped out of my bag, pulled on long underwear, a fleece jacket and rain pants, then a parka, and finally my bug net over my head. The mosquitoes bit me four times in the thirty seconds I was getting dressed. My dog and I hiked away from camp so we wouldn’t wake up my friend, Jill, who slept on in her bivy sack. Plus, the insects weren’t so bad if I kept moving.

Five minutes later I shuffled up a tributary of New Fork Creek, with Baty close behind, and then trudged tiredly up the hill to a flat, granite rock. Climbing up the rock, I looked for a breeze. Sitting on the boulder, the slight wind was enough to keep the mosquitoes away temporarily. Neither of us had slept much the night before and we were weary. I watched Baty close his eyes, relieved for a moment’s peace.

The day before we had left Jackson early and drove two hours to the North Fork Trailhead. We followed the North Fork Trail about ten miles until we were just west of Lozier Lakes. Stopping to make camp, I noticed Baty swatting his nose with his paw and licking mosquitoes off his legs. Jill and I donned bug nets, but there was no relief for my poor dog. I couldn’t apply my powerful (and toxic) bug spray to Baty because he kept licking himself. I tried to shove him in my bivy sack, but he hates tight places and used all one hundred pounds to fight his way out.

It’s not as though we weren’t prepared for this trip. Jill and I had stopped in Pinedale to buy Deet—a chemical bug repellent that melts watches and sunglasses. It’s something I don’t normally use, but I made an exception after hearing stories of horrendous mosquito populations in the Wind Rivers. In addition to the bug repellent, she and I carried pepper spray in case of bear attacks, a tarp for summer rain protection, sunscreen and hats, extra warm clothing, and plenty of food. In other words, we were ready for ten days of whatever the Wind Rivers threw at us. Except for watching Baty battle the bugs.

When the wind ceased blowing across the rock, Baty quickly opened his eyes and groaned, once again covered with insects. I swatted them away and tried not to hate them. I knew they were just doing what they needed to do to survive, these females blanketing my dog. Male mosquitoes suck nectar and plant juices and are important pollinators for many wildflowers. Females also feed on plant juices, but they need the protein found in blood to form their eggs. Besides what they feed on, males can be identified by their plumose antennae, whereas the female’s antennae have only a few short hairs. But, I was working so hard to keep the insects off Baty I wouldn’t have taken the time to observe their differences even if both sexes were attacking him.

While I didn’t follow any insects around, I realized that after a particular mosquito bit Baty, she flew away, filled with blood, to lay her eggs in water. Looking down the hill, I realized we were in a somewhat marshy area. The snow had only recently melted, leaving the alpine tundra moist and spongy. Puddles of water dotted the meadow near the creek.

The mosquito eggs take about a week to develop, then they hatch and the larvae crawl out. The larvae have a distinct head, but no legs. They hang upside down at a 45-degree angle, or flat under the surface of the water and breathe through an abdominal tube.

When I returned to Jackson after the trip, I borrowed books about mosquitoes from the library. I was hoping a better understanding of the role mosquitoes play in the ecosystem would help me appreciate them more. I found out there are over 3,400 species of mosquitoes in the world, all in the family Culicidae. Their taxonomic order, Diptera, also includes houseflies and tsetse flies. Diptera is from Latin, meaning “two wings,” but unlike most insects, flies only have one pair of wings. The other pair is reduced to vestigial appendages called halteres, which are thought to function as stabilizers in flight. Sensory organs at the base of the halteres decipher air currents and pass the information to the brain allowing the insect control and maneuverability.

The suborder to which mosquitoes belong is Nematocera. Their Nematoceran relatives include midges, sand flies and black flies. At the family level, mosquitoes fall into the Culicidae, which can further be divided into the sub-families Anophelinae (many of these species are responsible for spreading malaria), Toxorhynchitinae (whose enormous larvae eat other mosquito’s larvae), and Culicinae (which contains about 2,000 of the known species). Mosquitoes used to be called gnats, a derivation of the Middle English words “gnash” and “gnaw,” which is appropriate. But, what we call gnats today are their non-bloodsucking relatives. The name “mosquito” came from a Spanish word meaning, “little fly.” But, while they are little, mosquitoes can cause big problems.

Whether gnat or Culicinae, the species that had my attention was the one buzzing around my head. The bug net kept mosquitoes from touching my skin, but the insects were still extremely close and particularly loud for something less than six millimeters long. I watched them walk along the netting, only a few centimeters from my face while the shrill hum drove me crazy. Baty’s ears twitched in annoyance as the vibrations of tiny wings pierced the early morning tranquility.

A mosquito’s wings are attached to the muscle-packed mid section of its body—the thorax. Automatically, these muscles contract and relax, beating the mosquito’s wings 250-600 times a second. This rapid wingbeat gives the mosquito speed and agility as well as the annoying hum. The tone of the buzz comes from the vibrating thorax muscles and a scale-like structure over the respiratory opening on the thorax. The wing tone varies from species to species and is crucial to mating because a female attracts a male with her distinctive wingbeat tone.

Once she has attracted a male, the mosquitoes mate and the female stores the sperm in her body. Each time she lays eggs, she uses the stored sperm to fertilize them, getting up to 4-5 batches. But, before she lays the eggs the female mosquito must search for blood. That’s where Baty and I came in. She bites her victim, sucks out blood and then flies somewhere to wait. After she has rested and used the protein in the blood to form offspring, the mosquito lays one hundred or more eggs, which hatch in a few days.

What hatches is the larval form of a mosquito, called a wrigler. Most wriglers feed on organic debris, but a few are predaceous—those in the sub-family Toxorhynchitinae. After four to ten days, the back of the larvae splits open and a pupa pops out. The pupa doesn’t eat, but breathes at the surface of the water for about three days. Then, its head splits and an adult mosquito emerges and floats on the shell of its former self until its wings dry and its skin hardens. Then it flies away.

The first day we hiked up the New Fork Trail, Jill, Baty and I had passed only a few people. Travelers in this part of the Bridger Wilderness Area seemed to be spread out and distant from one another. Still, the mosquitoes had found us camped between two boulders on a hillside meadow, using sensors on their legs and antennae to locate us. They can sense warmth (I was cold), moisture, odor, carbon dioxide, some sounds (but, we were very quiet), and possibly other stimuli. Despite our attempt to hide, a hot, panting dog obviously drew mosquitoes from miles around, even if Jill and I had not been there. In addition, we were all releasing a steady stream of carbon dioxide, drawing mosquitoes right to us. Until an hour after dark, we were infested. Baty licked mosquitoes off his nose for dessert.

Mosquitoes prefer some people more than others based on their body chemistry. I know this must be true because I have hiked with friends who come home with just a bite or two, while I am covered with welts. Mosquitoes must like Baty, too.

From our perch on the rock, Baty and I watched a porcupine lumber up the hillside, its spines undulating over its back as it slowly picked its way between rocks and gnarled whitebark pines. Baty growled low in his throat, which I felt more than heard. He was distracted momentarily from the mosquitoes. Visually we followed the porcupine for about ten minutes, until it moved beyond our line of sight. I begged the sky for more wind, but was denied.

I watched the creek bound down the U-shaped, glacier carved valley and then I scanned up a granite wall to the top of a ridge. The rising sun turned the ridge pink and rose and then orange. Some of the lichens on the rock mirrored the colors on the ridge; others were lime green, dusty sage, gray and almost black.

Jill and I had been hoping to camp in snow, where the mosquito populations would have been smaller. Before we left Jackson, a Forest Service Ranger told Jill there would be two feet of snow above 10,000 feet, but save for a few small patches in shady recesses on the hillsides, there was none.

Another mosquito landed on Baty’s swollen, black nose. The insect lifted her tube-like proboscis ready to plunge through his skin. The mosquito’s proboscis was made up of six stylets surrounded by a labial sheath (a lower lip formed by the fusion of the second maxillae). It was the stylets that did the actual piercing as she drove all six into Baty’s nose. The stylets, consisting of two tubes, two lancets and two serrated knives, penetrated his skin about half a millimeter. The mosquito used her stylets to infiltrate one of Baty’s capillaries or veins and then the stylets bent to the shape of the vein and she injected a bit of saliva through two of the small tubes to prevent the blood from clotting. She sucked the blood into her abdomen, and a minute later she had a complete meal. If she had only ruptured the vein, instead of infiltrating it directly, it may have taken up to three minutes to fill up on blood. The stretch receptors on her abdomen told her when to quit taking in the blood. When the mosquito stopped drinking, a little residue of the anti-coagulating saliva left an irritating bite. Finally, she was done and Baty put his head flat on the rock and ran two paws over his eyes and down his snout.

As the sun filled the valley, Baty and I walked back to camp where we found Jill crouched over the stove making instant oatmeal. I ate the cinnamon apple porridge and Jill and I discussed hiking back out that morning and calling an end to the hike. We were disappointed to have to cut the trip so short, especially after all the planning and carrying heavy packs, but I couldn’t handle another night helplessly watching my dog besieged and neither could Jill. Baty turned his tired eyes and puffy snout toward my oatmeal, and I let him lick the bowl.

We rambled down the switchbacked trail, listening to birds singing and chipmunks chirping as if they didn’t have a care in the world. I wondered how animals handle mosquitoes, how they keep from going crazy. A slight breeze and our forward movement kept the insects at bay as thick clouds gathered and dissipated overhead. As the morning warmed we stopped and Jill and I shed our fleece shirts.

After our second knee-deep crossing of the New Fork River, we took off our backpacks and basked in the sun on the cobbles deposited by the river. I took off Baty’s backpack too, and he laid on his side, cushioned by his thick fur, legs straight out, and fell asleep, free from the hum of his tormentors.

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