A week of record temperatures can have an impact on fire ant populations in Arkansas, but it likely won’t reduce flies or ticks, said Kelly Loftin, entomologist with the University of Arkansas Agricultural Systems Division.
In general, Loftin said, “Insects that are endemic to our region have developed various mechanisms to survive cold winters.” However, invasive animals that hail from warmer climates do not have these means of survival.
“Imported fire ants are a good example of an exotic species that can be affected by extremely cold temperatures,” he said. “This pest ant has expanded its range as far north as possible under normal winter conditions. And northern Arkansas is the northern limit of its range. “
Fire ants help aerate the soil and eat other insects that can affect plants.
A decade ago, when parts of the state stayed below freezing for seven days, the fire ant population in Arkansas saw a 70% decrease in the number of fire ant colonies, he said.
But this decline will only be temporary.
“About a year and a half later, the fire ants returned to previous population levels,” he said. “Fire ant colonies connected to sidewalks, parking lots, foundations and other areas usually only survive because these structures act as heat sumps, preventing colonies from freezing.”
Ticks are pretty good at finding sheltered places to weather the freezing weather.
“Species like the American dog tick and the solitary star tick survive the winter by taking shelter in the foliage as adults and nymphs,” Loftin said. “Other species such as the winter tick are tied to a warm host in the cold winter.”
“If you look at the geographic range of the American dog tick, black-legged tick, and winter tick, all three survive to the Canadian border and beyond,” he said. “Even the lone star tick survives as far as the Great Lakes region.”
According to Loftin, temperatures affect when ticks become active.
“For example, if we have a warm spring, we will see active ticks in March or April,” he said. “And during the winter months, you may occasionally see an active single star or American dog tick in January or February during warm periods. If temperatures stay cold in the spring, ticks won’t become active that early. “
Don’t count on a week of freezing temperatures to eliminate flies.
“The range of houseflies is worldwide, including the Arctic. So obviously we wouldn’t expect high winter mortality rates,” Lofton said, adding that “our major cattle flies have different mechanisms to survive cold winters.”
Cattle houseflies and horn flies survive cold temperatures as larvae or pupae under dung heaps and other protected breeding material.
The face fly is a pest with a different hibernation strategy than an adult hibernating. Introduced from Europe to Nova Scotia, Canada around 1950, face flies overwinter in church spiers, attics, barns, and other protected areas.
“I routinely see hibernation face flies in man-made structures on warm days,” Loftin said. “Often they are numerous enough to become household pests.”
The effects of freezing are uncertain, said Ben Thrash, an entomologist with the Department of Agriculture.
“We can safely say that the redbound stinkbugs and the southern green stinkbugs will be pushed back for years to come,” he said. “I think many of our native species will remain relatively untouched.”
However, the effects of the common cold on insects migrating to Arkansas are not yet known.
“Insects like corn earworms and falling army worms hibernate here in Arkansas. The cold should have killed them here, but many of our most harmful populations of corn on the cob migrate from places like the lower Rio Grande Valley of Texas and southern Louisiana,” said Thrash. “I bet we’ll still see these insects, but they may just be late moving here.”