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The 2014 Farmers Almanac
Farmers' Almanac

Do Cold Winters Kill Pests?

Do Cold Winters Kill Pests?

For much of the United States and parts of Canada, this winter has been the coldest of the 21st Century and, for some, in more than 30 years.

The polar vortex that brought several days of subzero temperatures to the eastern half of the continent last month has made a lot of people uncomfortable – and led to some high heating bills during a difficult economic time.

Many visitors to our site, trying to find a bright side to the punishing cold, have commented that at least the cold year will mean fewer bugs this summer. But is that really true?

The answer is mixed, but entomologists who study invasive insects, such as the Japanese beetle and emerald ash borer, are optimistic that this winter’s extreme cold could deal a devastating blow to these pests, whose numbers have been exploding in recent years.

All insects have some ability to withstand cold weather. One of the most common strategies is to bury themselves underground, beneath leaf litter, or to burrow under tree bark for protection and hibernate for the season. These protective maneuvers work pretty well most winters, allowing insect populations to remain relatively stable.

A recent spate of warmer than average winters over the last few decades, however, has allowed the populations of some types of creepy crawlies to explode. When winter temperatures never reach a truly deep freeze, bugs make it through to spring unscathed and ready to multiply.

For instance, Lyme disease carrying deer ticks – which are not actually insects, but eight-legged arachnids, like spiders – are now seen in larger quantities and have spread farther to the north than they once roamed.

When temperatures drop well below 0° F, though, as they have this year, many individual insects die. The colder the temperature becomes, the fewer survive.

The actual temperature required to kill off pests varies across species. The emerald ash borer, for instance, can generally withstand temperatures as low as -20° F. Any colder than that, and about half of their population dies off. At -30° F, even more of the invasive pests are wiped out.

Some individuals will inevitably survive, but the reduced numbers could be beneficial to other species. For instance, a substantial reduction in the number of emerald ash borers could slow the predicted extinction of American ash trees. Likewise, gardeners and homeowners aren’t likely to mourn if Japanese beetles or brown marmorated stink bugs were less abundant this summer.

Fortunately, beneficial insects, such as honey bees, which are already threatened by a combination of commercial pesticides and widespread infection by a parasitic mite, are not likely to be impacted by this year’s cold winter. Bees hibernate in their hives for the winter and huddle together for warmth, emerging in the spring to resume their annual flower feast.

35 comments

1 Diane { 03.16.14 at 9:05 pm }

I hope this winter will make a big difference in mosquitoes & ticks in SE, PA. Still searching the web for comments/predictions on this.

2 Penny { 03.12.14 at 1:19 pm }

To DaWanda, we were advised that the Asian beetle (looks like a yellow lady bug) takes refuge under your house siding and a good way to control their population is to power wash your house every spring. We also have a siding mold problem in our area, so we add a small amount of bleach to the power wash cleaner. We have almost entirely eliminated the beetle problem.

3 DaWanda { 03.02.14 at 12:04 pm }

My house has been invaded by the Asian Lady Bug all winter. They are seen in every room of my home! One bit me on the hand last week! I think they lay their eggs under anything they can crawl under and they hatch when the temps get warmer. They can crawl through to the inside of your house. I wish I knew a good cure for squash bugs and borers. They ruin my squash every year!

4 Kate { 02.27.14 at 1:08 pm }

Jamie, I was thinking about the first flowers(bulb) to emerge in spring. Their pollen seems heavier, not in the air. Is it a heavier pollen to feed a very hungry bee?

5 Jaime McLeod { 02.25.14 at 9:18 am }
6 Meghan { 02.25.14 at 7:20 am }

In response to Patty in Montana whose daughter was diagnosed with Lyme disease, the young (nymph) deer ticks can be the size of a poppy seed. If you are bitten by one it is easily missed. Symptoms will not appear until 2 weeks after and may start out only as a short-term low-grade fever. If you develop a “bull’s eye” rash it will not necessarily be in the area of the tick bite and could be in numerous locations on your body. Blood tests for Lyme are accurate. Take this seriously. Symptoms of chronic Lyme disease are debilitating.

7 Jaime McLeod { 02.24.14 at 6:39 am }

Roaches have adapted to live indoors. A very cold winter will not kill them.

8 Michael Carpenter { 02.23.14 at 2:54 am }

What temp is required to kill roaches?

9 Diane { 02.20.14 at 10:55 pm }

Hoping the flea population is down here in Northern Indiana. Our dog is on flea pills and I’m a “clean freak”, but last year was the pits!

10 Jaime McLeod { 02.20.14 at 4:04 pm }

Cold has no effect on pesticides. They’ll just keep spraying ‘em.

11 Jaime McLeod { 02.20.14 at 4:02 pm }

Native pests are used to local conditions. An exceptionally cold winter is unlikely to affect them to any great degree. Only invasive insects or insects that have expanded their range are likely to be affected.

12 J { 02.20.14 at 2:38 pm }

I’m in Prince George, BC, and hoping that the cold snap we had for about 2 weeks(-30°C) has or will destroy some of the tent caterpillar larvae.

13 Laurie { 02.20.14 at 7:27 am }

Don’t worry about killing box elder bugs. They eat dead plant material and will not bother your dog. They eat Maple seeds, remove the seeds and you’ll reduce the numbers.

14 Andy White { 02.20.14 at 1:58 am }

Bees don’t hibernate in the winter. Just letting you know

15 Gale Slack { 02.19.14 at 6:24 pm }

will it kill the stink bugs,we have them bad in Marshall Virginia

16 Vicky { 02.19.14 at 6:13 pm }

I have noticed a lot of box elder bugs have been making their appearance more so than usual. I am not sure how to kill them when spring comes as I have a dog that uses a pen where these bugs usually are at. I don’t want to spray harmful bug killer inside the pen.

17 Lorrie { 02.19.14 at 6:03 pm }

I’m noticing lots of questions, but no answers to them? My concern is more for a diminished population of black flies, mosquitoes, deer flies, horn flies, horse flies… basically, what kind of a summer are my horses going to have?

18 Patty { 02.19.14 at 4:37 pm }

I thank you for this article. We don’t have many of those pests here in Western Montana but we are inundated with Yellow Jackets and paper wasps, hard to take care of them without getting the bees, they love the traps as well. But I did learn something new, I didn’t know that deer ticks are like spiders, I thought a tick is a tick, just different sizes. Hence, it is possible that our daughter was bitten and ended up with lime disease. We had never found a “Tick” like you do in the mountains and on other critters so strongly disagreed with diagnoses. Hum, seems I owe someone an apology. But Dr.s need to be aware of what “deer ticks” look like as well. thanks again.

19 merrily westerhaus { 02.19.14 at 4:04 pm }

Wichita Kansas, will the freezing cold impact snakes? I sure hope so. Hope it will help with skunks.

20 Kathryn Matty { 02.19.14 at 3:52 pm }

Need to know will the cold have any affect on fleas. I’m so hopeful, but I feel the nasty little fleas wil be spared!!!!!!

21 Pam Sanders { 02.19.14 at 2:57 pm }

What about Africanized killer bees and fire ants? Can we expect to see less of them due to the severe winter we’ve had here in Tennessee?

22 K.B { 02.19.14 at 2:49 pm }

what about Praying Mantis egg pods? after 3 years I finally had some Mantis’ lay egg pods-really hoping they survived this bitter cold in NH.
I notice a huge reduction in the tick population every year. and less Stink Bugs..

23 M.P. { 02.19.14 at 2:03 pm }

-20 in SWVA hope it killed more than 50%

24 Jc { 02.19.14 at 1:51 pm }

Best thing for bugs is to stop using chemicals and lat nature take Cate of itself. Here, in my urban-esque area of KY, they spray for mosquitos. 40 min away, my friends have an organic farm, my csa provider. There, you can watch the bats dive bomb the little blood suckers. No issues with mosquitoes as a result. At home I get eaten uo, there nothing. Locally, the cold will help as blue mold for tobacco farmers is an issue and will be reduced. Hoping our winter impacts buggies too.

25 Pamela { 02.19.14 at 1:50 pm }

Jaime, do u think that this cold will kill off some of the pesticides for the bees? Curious! I am hoping so, at least dilute it some.

26 martyelzz3 { 02.19.14 at 12:47 pm }

In response to Larry Wallace. I lived in Alaska and worked all over Alaska for 21 years… the mosquitoes are out flying while the snow is still on the ground. I really doubt they will be killed off unless some southern climate mosquitoes are not cold resistant… perhaps there is an insect expert around who will respond to the question for your area.

27 Keith { 02.19.14 at 12:38 pm }

We live in Ontario, Canada close to Perth. It may be wishful thinking, but I would love to see the mosquito population reduced by the extreme cold.

28 Sara { 02.19.14 at 12:31 pm }

I hope the 4 degrees (not calculating wind chill) we had in western Tennessee will kill of lots of bugs. Mosquitoes, stink bugs and squash borers just to name a few. Although I hope the frogs and toads will go unharmed.

29 Linda { 02.19.14 at 12:03 pm }

I was hoping to hear something mentioned about grasshoppers. Last year, in the DFW, TX area they were unstoppable. In fact, the last couple of years. After last year, I swore I wouldn’t do another garden unless we got a decent winter that took care of them. I refuse to put all of that work and money into a garden only to have it eaten and destroyed by grasshoppers.

30 Carolyn Dachenbach { 02.19.14 at 11:35 am }

We are in the eastern panhandle of West Virginia. Lots of gnats this past year. Hoping this weather will help destroy them. Hard to get rid of the leaves, that they winter over in, when you live in the woods on a mountain.

31 Pat Gleghorn { 02.19.14 at 10:15 am }

Teri, getting rid of ‘palmetto bugs’, aka roaches-the giant variety-is just a pipe dream. Haven’t you read they could probably survive a nuclear holocaust? When I lived in MS, they would fly in like little kamikazes. If it weren’t for making holes, I would have shot them. Seriously stomping them seemed to be the only solution.

32 Kris { 02.19.14 at 10:15 am }

It was 5 degrees in Atlanta during the second week in January, so I believe we will see a noticeable difference in mosquitoes.

33 Cararta { 02.19.14 at 10:03 am }

Hmmm,
Reading the comments! I think it got a wee bit cooler than 17 degrees in neighboring Atlanta, Ga. !!!!
At least where I live in Tennessee it went down to -7 so hopefully some of those Lyme Ticks will bite the dust right along with that Asian Lady Bug look a like.
The imitation Lady Bug has had at least three “die offs” in the house….keep sweeping them up and disposing. When it warms up outside from a good cold spell, they come out and
die.
I’m still amazed at their numbers.
The seem to have access from the attic…mine is an old house (1933) but neighbors with new homes seem to have the same problem.

34 Larry Wallace { 02.19.14 at 9:41 am }

How does extreme cold affect Lyme ticks and ticks in general? Also, how does it affect mosquito larve for the coming year?

35 Teri Kemper { 02.19.14 at 9:28 am }

In Atlanta, GA the coldest temperature was around 17 deg. F. I’m wondering if such a mild low temp. could impact our pest population. I’m thinking specifically of fleas and palmetto bugs.

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