Petty about Rain

Water from heavy rains lasts longer, give mosquitos extra time to reproduce. Photo by Anne Liu
Ah, a pretty picture… of a perfect mosquito habitat! Heavy rains create longer lasting pools of water, giving mosquitos extra time to reproduce. Photo by Anne Liu

Remember back to just a few weeks ago when it was July, when it seemed like not a week could go by without at least a day of rain? For many counties across New York, the large amounts of precipitation have put this past July in their top 5 wettest July’s in recorded history. Most people wouldn’t normally think that rain is a bad thing, after all, water brings about and nourishes all kinds of life. For the many farmers growing feed corn and cash crops, the rain must have been welcome after a dry period last year and the unusually hot days in early July. At least they must have been glad until the water kept coming, at times building up to over 3 inches of rainfall a day, flooding fields and setting off flash flood warnings across multiple counties at once. Now though, the National Weather Service is predicting that August will be more normal, so why am I still talking about the unusual amount of rain that’s ‘so last month’? Well, it’s actually a mosquito resurgence that gave me the urge to expound on this topic.

The extra rainfall this year has inundated the forested wetland habitats at Iroquois NWR and refilled marshes and ponds. While it’s great that vegetation has been growing well, mosquitoes have also been having a blast with all the extra water. The newly flooded habitats provide more opportunity for mosquitos to lay eggs and mature in huge numbers. Because it takes about a week for mosquito eggs to develop into adults, they’re an effect of the rain that doesn’t show up until after any immediate flooding troubles are over. “Well,” you say, “Don’t mosquitos show up any time after a rain? What is it about this mosquito resurgence that is so special that you felt the need to highlight a natural process???” To be honest, most of my reason is simply that mosquitos are terribly annoying pests, but there is a lot more to this than just personal annoyance.

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Our Purple Martin Researchers at the refuge found Mosquito net jackets to be very helpful in conducting radio surveys. Photo by Dr. Heather Williams.
Our Purple Martin Researchers at the refuge found Mosquito net jackets to be very helpful in conducting radio surveys. Photo by Dr. Heather Williams.

Whether you believe in climate change or not, the average annual temperatures across New York have increased by 2.4°F since 1970 according to the DEC. Average yearly precipitation has also increased alongside larger rain and snow storms, meaning that it’s more likely for too much water to come all at once instead of being dispersed across a season – much like we saw in July. Longer mosquito seasons and better conditions for them to reproduce in are a result of warmer temperatures and heavier rainfall. Heavier rainfall also has an effect on increasing mosquito populations. Heavy rains provide more standing water than smaller showers do, and the pools don’t dry out quickly. This allows mosquito larvae to develop more fully, as well as for less common species of mosquito to have the opportunity to spawn and mature. As the weather and climate change, so do the existing conditions for different kinds of life. For now and in the long run, it seems like we should be prepared to face the likely reality that many bugs populations will continue to benefit from warming temperatures.

You may need a transfusion if you get bit by too many of these guys... Photo by Anne Liu
You may need a transfusion if you get bit by too many of these guys… Photo by Anne Liu

A last note, mosquitoes are a significant disease vector (as if leaving an itchy bite isn’t enough). You may not see as many of them in the city, but you can currently expect larger than normal swarms in any outdoor parks and any spaces near standing water. To prevent getting bitten by bugs in general, you should wear long sleeves and long pants if you’re planning on being outdoors, and can use mosquito netting or bug spray as well. Sadly I’ve found that most mosquitos in the field can bite even through jeans, so while it is good practice, just being covered probably isn’t enough on its own.