Weather Forecast


Heat, humidity bring on mosquitoes to region

Get ready for those raised bumps on your ankle and red splotches on your shoulder. The hotter weather means mosquito season is here in full force.

Predicting the future of mosquito outbreaks is like forensic science, said Ben Prather, director of Cass County Vector Control, Fargo's primary mosquito abatement program.

Vector Control workers sample mosquito traps daily to determine when the next major insect surge should occur, and where they need to spray with insecticides.

After cooler conditions in April and May, Prather said the surge of mosquitoes this week went on like a light bulb, with a perfect storm of rapidly warm and wet weather increasing the mosquito maturing process.

Generally, a rule of thumb is that 90 percent of area mosquitoes are going to arrive anywhere from 7 to 14 days after a rainfall of at least an inch, Prather said.

"With all these spits of rain we've had in the past 6 to 12 days and the jump to 90-degree temps, the emergence of mosquitoes was more rapid than we expected," he said.

Future mosquito outlooks depend on the weather. Prather said if the days stay humid, robust mosquito development will continue.

Spraying synthetic chemical insecticides is contingent on the results of these traps, as well as the weather and public feedback, Prather said.

Moorhead's mosquito-fighting program relies on the same thresholds, said Chad Martin, the city's operations manager.

Out of the nearly two dozen traps set in the metro area, if one trap collects 35 females or more - since the lady skeeters are the ones that bite - Prather said residents typically begin to call, an indicator that more action needs to be taken.

Prather said when checking traps Tuesday and Wednesday, the bug count was nearly 130, a major spike. Vector Control responded by spraying down areas of Fargo and West Fargo from about 7 p.m. to midnight. He said within a few days, the numbers were down to about 38.

But spraying is not always the answer. It only lasts for 30 minutes, and its effectiveness depends on climate conditions. Also, Cass County can generally only apply the insecticide on a weekly basis when the thresholds are met.

But Prather hopes to keep Vector Control ahead of the swarm by assessing and monitoring standing water sites. By spraying larvicides on water pockets, the goal is to kill the mosquito before it reaches the end of its 14-day metamorphosis cycle.

This is a widely used approach, Martin said. He said while Moorhead mosquito counts are lower than Fargo's at the moment, it is still easier killing mosquitoes on the ground than in the air.

Preventative action is important for large-group outdoor activities, said Clay Whittlesey, director of recreation for the Fargo Park District and member of the Vector Control Board. Whittlesey said park officials provide Vector Control a list of major outdoor summer events, so they can plan accordingly.

Whittlesey gave a recent movie night in Fargo as an example, as nearly 1,000 people attended the event. With recent rains, Vector Control sprayed prior to the event, and Whittlesey said he saw maybe one mosquito the whole night.

"Vector Control is excellent at communicating and working with the people of Fargo and even groups in other communities, like Moorhead and Dilworth," he said. "They know exactly what to look for with those traps, and they stay ahead of the game."