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2015 Fall Pest Forecast: Above-Normal Mosquito Populations to Agitate More Than Two-Thirds of US

With the start of autumn comes more unwelcome pests seeking shelter in our homes. The size of these pest populations depends largely on the weather patterns of the spring and summer seasons.

The National Pest Management Association (NPMA) recently released its Bug Barometer Forecast, indicating what Americans in each part of the country can expect from pest populations this fall and upcoming winter.

"From the extreme heat and humidity in the Southeast to record rainfall in the Midwest and an ongoing drought in the Pacific Northwest and on the West Coast - the National Pest Management Association's (NPMA) Bug Barometer takes into account the weather patterns of the summer season in every region of the country," NPMA stated in a press release.

NPMA added that although spring and summer are typically the most active seasons for the majority of pests, autumn does not necessarily mean an end to pest activity.

Dr. Jim Fredericks, chief entomologist from the NPMA, said that a team of entomologists at NPMA looked at what has happened in the past and based on that try to get an idea of what the pest populations might look like in the upcoming months based on what is already known about their biology and behavior.

"For instance, insects and arthropods (such as spiders and ticks) are cold-blooded so their activities and biological systems are highly dependent on temperature," Fredericks said. "When temperatures are higher, their activity, metabolism, their physiological processes increase. They grow and move more quickly when temperatures are higher. When temperatures get too cold, two things could happen: they may die or go into a state of hibernation."

From this, the NPMA creates what they call the "pest pressure index" for each region of the United States during the fall season.

JUMP TO: Northeast | Southeast | Midwest | Pacific Northwest | West Coast | Southwest


Consistent warmth in May across the Northeast followed by periods of record-setting rainfall and exceptional humidity has provided ideal conditions for pests to remain active.

"Mosquitoes, especially, are expected to take advantage of an increase in areas of standing water and remain active until temperatures consistently dip below 50 degrees," NPMA said in a press release.

NPMA added that the summery conditions have set the stage for tick populations to remain at average levels well into the fall.

The brown marmorated stink bug population is very high due to the heat and humidity over the summer in the Northeast. (Flickr Photo/Mike Lewinski)

Overwintering pests such as such brown marmorated stink bugs and multicolored Asian lady beetles have benefited greatly from the heat and humidity across the Northeast this summer.

Fredericks said that these overwintering pest populations are very high right now and as they move into structures, the NPMA expects high pest pressure.

He added that as temperatures cool in the Northeast that the NPMA expects to see rodents, particularly mice, to move into structures.


The typical summer weather of hot and humid conditions has allowed insects to develop faster than normal.

"These summer conditions were also ideal for overwintering pests, such as kudzu bugs, multicolored Asian lady beetles and brown marmorated stink bugs, as the elevated heat and humidity encouraged growth and helped provide ample sources of food," NPMA said.

NPMA added that termite activity may increase as well due to the abundance of moisture so homeowners should stay vigilant as the termites may be foraging throughout the winter.

"The Southeast will probably continue to see some high ant pressure," Fredericks said.

He added if there are extended periods of dry weather that the NPMA would expect to see ants moving into structures to seek moisture. This will continue to happen until the weather begins to cool.


Record rainfall through June led to an increase of standing water and an excess of mosquito breeding sites across much of the Great Plains and Midwest.

"Mosquito activity will remain high in early fall, until temperatures consistently fall below the 50-degree mark," NPMA said.

However, NPMA noted that areas that were inundated by the most severe flooding may experience a drop in pest populations due to developing insects that may have not survived the extreme weather events.

Pacific Northwest

Record-breaking heat combined with the ongoing drought conditions experienced during the spring and summer months kept pest populations lower than normal.

"While heat is a favorable condition for pest populations, extreme heat without accompanying rain is less so," NPMA said.

Tick populations are lower due to the dry conditions across the Pacific Northwest. (Flickr Photo/Fairfax County)

Those who enjoy spending time outdoors will find that current mosquito and tick populations have been low, NPMA said, adding that these populations will likely remain down this fall.

"The heat and drought conditions creates unique situations for pests, especially in the Northwest where we [NPMA] would normally expect to see more rain," Fredericks said. "Because of these drought conditions, pests are moving indoors."

Fredericks stated that residents in these areas might see ants and other typical perimeter pests that are moving indoors in search of moisture.

West Coast

Though beneficial rain during July set monthly records in various cities in California, it did not bust the extreme drought.

"However, experts say the rainfall ultimately will not be enough to stave off the ongoing drought, and areas that received rain, but not enough to cause flooding, can expect pest populations to be slightly higher than in recent years," NPMA said.

The pests that have benefited from this rain are mosquitoes and they will remain active in these areas during fall until temperatures consistently remain below 50.


Triple-digit heat and above-normal rain in drought areas have provided excellent conditions for mosquitoes, ants and flies.

"Termite foraging and unseen damage to wood may be higher than usual, and mosquito breeding sites are likely at a surplus thanks to an abundance of moisture," NPMA said.

Fredericks noted that usually when temperatures are consistently below 50, a sharp decline in pest populations outdoors occurs and these pests will not been seen as much indoors though it will vary for each pest population.

Stinging insects like the yellow-jacket are at peak populations this time of year. (Flickr Photo/Bob Peterson)

"One of the pests that is affected by temperatures and is really important for this time of year would be any of the stinging insects such as yellow-jackets, hornets and paper wasps," Fredericks said. "All of those are at their peak population level now, and we won't see those pests begin to decline until we have temperatures consistently below 50 F."

He stated that NPMA found that temperature and moisture levels, whether that be from rainfall or humidity, are the most critical factors in active pest populations.