Reading conditions for mosquitoes

Questions and reports related to Sierra Nevada current and forecast conditions, as well as general precautions and safety information. Trail conditions, fire/smoke reports, mosquito reports, weather and snow conditions, stream crossing information, and more.
Post Reply
User avatar
Talimon
Topix Acquainted
Posts: 49
Joined: Mon Jun 13, 2011 11:49 pm
Experience: N/A

Reading conditions for mosquitoes

Post by Talimon » Fri Jun 26, 2020 3:08 pm

I'm curious if folks with more experience here have a decent sense on the pattern of mosquito "migration" at various elevations as the early season progresses. My general sense is that as June and July progress, they climb higher and higher, chasing the new snow melt. Does this pattern mean they start to thin out at lower elevations?

In other words, would a trip in early July at 6,000 ft be considered a safer bet to avoid swarms than a trip at 10,000 ft? I realize there are many other factors, but just curious what everyone's experience is.








User avatar
balzaccom
Topix Addict
Posts: 2097
Joined: Wed Dec 17, 2008 9:22 pm
Experience: N/A

Re: Reading conditions for mosquitoes

Post by balzaccom » Fri Jun 26, 2020 5:31 pm

Nope. Completely depends on the year, the snow, and the temperature. We've seen almost no bugs this year, but we've heard from other folks who say they are horrendous.
Balzaccom

check out our website: http://www.backpackthesierra.com/" onclick="window.open(this.href);return false;

User avatar
wildhiker
Topix Expert
Posts: 655
Joined: Tue Jul 26, 2011 4:44 pm
Experience: Level 4 Explorer
Location: Palo Alto, CA
Contact:

Re: Reading conditions for mosquitoes

Post by wildhiker » Fri Jun 26, 2020 7:44 pm

I disagree with Paul. In my experience, mosquitoes do abate sooner at lower elevations. Of course, what really happens is that they abate when an area dries up, but that generally happens first at lower elevations. All of this is subject to local conditions that are independent of elevation, such as prevalence of small ponds for breeding and windiness.
Phil

User avatar
rgliebe
Topix Novice
Posts: 14
Joined: Sun Jul 22, 2012 1:27 am
Experience: N/A

Re: Reading conditions for mosquitoes

Post by rgliebe » Fri Jun 26, 2020 8:53 pm

I do agree that mosquitoes tend to die out at lower elevations first, since they hatch there first. But there are exceptions, since several days of warm weather can cause them to hatch at a certain altitude, and if a string of subfreezing nights follows, many of those that hatched will die, creating a situation at that altitude where there are fewer mosquitoes for the rest of the season. If you watch the weather reports daily in the late spring combined with watching the snow levels, you can get a good feel for what is unfolding at a given altitude and whether this type of situation happens.

However, you will find that each drainage is a bit different. I've taken trips that crossed through two or three different water drainage systems (related series of creeks/rivers) at nearly the same altitude and observed completely different levels of mosquito activity. Some areas just seem to be worse than others, and sometimes there isn't much logic to it (like more trees that they like to hide under, etc.) One of the best things you can do is find a campsite that is at least 100 feet away from water (the more the better), has minimal or no tree shade, and has regular wind gusting through it at greater than 5 mph (often on a ridge or small rise). If you do that, your chances of being harassed by them constantly will drop considerably. The time of day is also critical, as they get stronger as the day goes on and peak in the evening an hour or two before sunset. They die down when it cools off at night and hide if it gets close to freezing. Use the early morning cold weather to do as much as you can before they come out of hiding again.

User avatar
kpeter
Topix Expert
Posts: 978
Joined: Mon Jan 04, 2010 1:11 pm
Experience: N/A

Re: Reading conditions for mosquitoes

Post by kpeter » Fri Jun 26, 2020 11:12 pm

Sierra mosquito eggs overwinter in ice and hatch about 10-14 days after they thaw. Then, generally they take 6-8 weeks to run their course of multiple generations before predators and drying conditions thin them out. But elevation is not necessarily a good guide, since mosquitoes can fly or be carried by the wind for a couple of miles, including over large elevation differences. But it is true that since the snow mostly melts at lower elevations first, the cycle starts and ends sooner there that at high elevations.

In a typical year with average snowfall I usually find lower elevation destinations like Emigrant good for the last week of May and about 10 days into June, then the mosquitoes come out in force and make late June and most of July unbearable. I try to get a trip in before mosquito season each year, knowing that a for a month or so after conditions are poor. It is tricky since too early and you cannot ford the streams, and too late and the air is grey with mosquitoes. Tough to time it right.

Also fairly typically at higher destinations I find the second week of August is the sweet spot, but the last week of July and first week of August are usually reasonable. I have hit horrid mosquitoes in Sabrina Basin in the 2nd and 3rd weeks of July, for example, but have not had a bad trip there in August.

Then you have to adjust for atypical years, which seems to be most of them! After the big snow year in 2017 I hit some of the worst mosquitoes of my backpacking career after Labor Day at Big McGee lake. A big snow year and that lake basin is shaded to the south by Red and White Mountain. There was still a lot of snow on the ground in September! And mosquitoes to match it.

In contrast, this year is a low snow year and so we can expect the mosquito season to end earlier than usual. I'm taking a risk and heading to Pioneer Basin in the second week of July. I am hoping the mosquito season is over 2-3 weeks earlier than usual, but I am sure I will hit at least some. If you miscalculate, then there are a great many things you can do to prevent them from ruining your trip. This forum is full of that advice.

User avatar
balzaccom
Topix Addict
Posts: 2097
Joined: Wed Dec 17, 2008 9:22 pm
Experience: N/A

Re: Reading conditions for mosquitoes

Post by balzaccom » Sat Jun 27, 2020 6:27 am

I should amend my response. Yes, mosquitoes tend to follow the snowmelt by about two or three weeks. But when or where that happens in any given year is always a crapshoot. And a couple of rainstorms can start the process all over again.

This year, a dry year, to my utter amazement we had ZERO mosquitoes two weeks ago at 6500 feet near Carson Pass, and ZERO mosquitoes in Lassen last week. I would have bet a considerable sum against that result.
Balzaccom

check out our website: http://www.backpackthesierra.com/" onclick="window.open(this.href);return false;

User avatar
Lumbergh21
Topix Regular
Posts: 394
Joined: Mon Oct 31, 2016 10:11 pm
Experience: Level 3 Backpacker

Re: Reading conditions for mosquitoes

Post by Lumbergh21 » Sat Jun 27, 2020 7:51 am

balzaccom wrote:
Sat Jun 27, 2020 6:27 am
I should amend my response. Yes, mosquitoes tend to follow the snowmelt by about two or three weeks. But when or where that happens in any given year is always a crapshoot. And a couple of rainstorms can start the process all over again.

This year, a dry year, to my utter amazement we had ZERO mosquitoes two weeks ago at 6500 feet near Carson Pass, and ZERO mosquitoes in Lassen last week. I would have bet a considerable sum against that result.
I was surprised last weekend. I was hiking in the Trinity Alps north of Coffee Creek almost entirely between 5000 and 7000 foot elevation and came prepared for mosquitos. I killed three the second night, and that was it for the 3 day trip. I can only guess that it was due to the storm that came through 2 weeks prior. People were reporting snowfall above 6000 feet elevation.

User avatar
SSSdave
Topix Addict
Posts: 2954
Joined: Thu Nov 17, 2005 11:18 pm
Experience: N/A
Location: Silicon Valley
Contact:

Re: Reading conditions for mosquitoes

Post by SSSdave » Sat Jun 27, 2020 10:44 am

Mosquitoes prefer cool damp vegetation areas, and one will find at least some of them in such areas all summer regardless of altitude. After ephemeral pools and streams dry up at lower elevations, one will still find them in permanently marshy areas, wet dense forest meadows, and along permanent vegetated north facing seep streams. Not so much along lake edges.

For example Blaney Meadows along the South Fork of the San Joaquin River at only 7k or along the many north facing seeps along the main Mono Creek Canyon. What keeps numbers low in such wet shaded lower elevation zones after other pools dry up are voracious damselflies and dragonflies, but they are only out from mid morning through mid afternoon so early/late is when the few mosquitoes in such areas also venture out.

There are plenty of lower elevation places where once pools dry up are relatively free of mosquitoes as long as one avoids the minor areas of the above. Likewise early season one can avoid mosquitoes where they are usually dense if one visits after a cold enough front moves through that is able to freeze their usual shallow snow melt pools killing them and their wigglers. That is why on the below mid June trip in 2017, I saw almost none up at the 7k to 8k elevations where I went while modest numbers along the Kibbie Ridge trail at 5k to 6.5k in still wet shaded areas as I visited right after a late storm with snow down to 6k.

https://www.davidsenesac.com/2017_Trip_ ... 17-12.html

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests