Why Colorado’s High Country is seeing a bounty of certain insects

News News | Aug 5, 2023

Whether you’ve been hiking, biking or merely spending time outside this summer, you’ve likely noticed the abundance of mosquitoes, flies and other insects. While hard to quantify, there are certainly more than your average year.

“Yes, it’s been a buggy year,” said Melissa Schreiner, a regional entomologist for the CSU Extension based out of Grand Junction.

Sophia Agostini, the assistant general manager at Piney River Ranch, noted that they’ve seen a “huge increase” of mosquitoes and flies — so much so that “every guest comments on it.”

Despite this, however, Agostini said they haven’t seen any impact on visitation numbers.

Within the White River National Forest, David Boyd, the forest’s public information officer, commented that the wilderness rangers have noticed increases in biting flies and mosquitoes.

The reason? “It’s been a drought-breaking year,” Schreiner said.

“It might be annoying, but it is a symptom of a successful winter here in the mountains,” said Scott Dunn, the community programs manager for Walking Mountains Science Center. “We love having the snow, and this is kind of one of the consequences.”

Of course, it’s not quite that simple. While the increase in moisture has certainly caused more insects — including mosquitoes, flies and ticks — to be more abundant, it’s not a blanket increase for all insects.

“There could be population fluxes or there could be insects that are impacted by that water in a negative way so that they don’t thrive. There are population booms, population recoveries and there are probably collapses too. But there’s going to be species composition changes,” Schreiner said. “The relative abundance and distribution of insect species within an ecosystem is always going to be altered in a drought-breaking year.”

For insect species that thrive on moisture, this year has been a dream.

“When we’ve had a significant and severe drought for such a long time, and then all of a sudden we get around 170% moisture, that’s going to change the soil feed bank seeds that are going to grow that haven’t grown because they have adequate moisture. Insect eggs in the soil are going to receive suitable moisture and then hatch out,” Schreiner said.

This includes mosquitoes, for which standing water serves as the habitat in which they breed, as well as ticks, cockroaches and more, Schreiner said.

In addition, Schreiner has been hearing lots of reports of no-see-ums and other small biting flies. These have been “causing a ruckus in cattle production,” she noted.

“I’m not seeing tons of the flies affiliated with chicken and horse manure as much. I’m actually getting a lot more complaints about a tiny, not very obvious-looking fly. They’re called punkies or no-see-ums — they’re Ceratopogonidaes — and they’re flies that live up in desert ecosystems and their life history and biology is somewhat actually unknown,” Schreiner said.

“They’re thought to come out of a soil, and so when there’s suitable moisture that allows those eggs to thrive, then they’re going to hatch out in more numbers than maybe in a typical year if moisture had been limited,” she added.

The exact increase in insect numbers can be hard to quantify as many data points are anecdotal. The Colorado Department of Public Health relies on local surveillance for ticks and mosquitoes — which has demonstrated larger numbers of both species —so it only sees what people send in, said Natalie Marzec, the Zoonoses and One Health program manager at the Colorado Department of Public Health and Environment.

It’s also something that you shouldn’t expect to go away any time soon.

“It’s going to impact the whole season. From the spring until the end of the year, we’re going to see changes across the landscape and that’s just simply because the system has changed, the equation has changed, and the outputs of that are different,” Schreiner said. “So far, the spring and the summer have been wild, so I’m not going to expect anything different for the fall, frankly. We’ll see how the pattern stays.”

For high Alpine areas, bugs will likely be present up until the first freeze.

“Mosquitoes breed throughout the summer, so as long as there is standing water for them to lay their eggs in, they will do so until we hit our first hard freeze, and then they go into senesce,” Marzec said. “Similarly, ticks, depending on the species, are more active in different parts of the environment at different times of the year.”

Ultimately, Schreiner is “looking forward to seeing what comes with the moisture and how this shift is going to impact things in the long run”

For the Colorado Department of Public Health and Environment, much of its surveillance is for tracking diseases and infections associated with insects.

“As long as you’re outdoors in the summer, there is a risk of coming across mosquitoes or ticks that could have infections,” Marzec said.

The main mosquito-borne disease is West Nile virus. Marzec said the first human case of West Nile was reported in Colorado in July. The incubation period is 14 days after the mosquito bite, she added.

“Given how many mosquitoes one is likely to encounter when outdoors in the summer, it can be hard to link a specific mosquito bite to an illness,” Marzec said, adding that symptoms to look for can include fever, headaches, neck pain as well as confusion with severe infections.

Typically, Colorado sees the peak of human cases for West Nile in August or September, a couple of weeks after it peaks in the mosquitos.

The state department also tracks tick populations. While Colorado does not have a presence of Lyme Disease, there are a variety of other tick-borne diseases in the state. The “most concerning” of which is Rocky Mountain spotted fever, Marzec said.

This is a bacterial disease that “may or may not include a rash that would occur after a tick bite,” as well as a fever and headache as symptoms, she added.

Ticks, when attaching to both humans and animals, like “warm, moist areas,” including under waistbands, in underwear and under armpits for humans as well as in skin folds or areas with those characteristics on animals, Marzec said.

And, if you find a tick: “Get your tweezers and pull that sucker out,” Marzec said.

She added that you want to get as close to the skin as possible to pull the entire tick out — including the head, which will be closest to the skin. Plus, don’t believe the old wives’ tales about using a lighted match or Vaseline, she said.

With both species, the department recommends using insect repellants (per label instructions) that contain DEET and Picaridin as well as wearing long pants, long-sleeve shirts and socks in areas where they might be active. Spraying the repellants on clothes can serve as additional protection, Marzec recommended.

“Limiting outdoor activities at dawn and dusk when the mosquitoes are most active is also a good idea,” she added.

For ticks, which live in tall grass and brush, avoiding this or eliminating it from around your house is a good preventative measure.

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