Spring mosquito bites bring few threats to humans; August and September are another matter.
Only the females mosquitoes bite humans, as they seek a blood meal in order to lay eggs. To a mosquito in spring, relentless rain is the equivalent of life-giving sunshine.
And after a March, April and May when rainfall was nearly 25 percent above normal in Greater Springfield (including 10 consecutive days with some amount of rain starting May 14), mosquitoes have certainly come to life.
“I know I’ve been working in my garden, and I’m being eaten alive,” said Stephen M. Rich, an entomologist and head of the University of Massachusetts Department of Plant, Soil & Insect Sciences.
“Mosquitoes have a juvenile phase in water. And, if there’s lots of water around, there are a lot of mosquito larvae,” he said.
However, the fact that the Connecticut River – or a local pond – is near flood stage won’t particularly affect mosquito populations, Rich added.
“What makes a difference is the little stumps and small ditches and other places (where) water collects. Some of the more problematic varieties breed there. And, without a lot of rain, water will not accumulate in these places,” he said.
More than 150 different species of mosquitoes have been found in North America, including 51 in Massachusetts.
Mosquitoes lay their eggs in water, and the larvae that hatch remain in water until they reach adulthood and fly away. However, an adult mosquito’s life is short. Most females live for less than two weeks. Most males may last only a week.
However, it is only the females that bite, as they seek a blood meal in order to lay eggs. They are attracted to the carbon dioxide that humans and other animals exhale.
“One thing we can say each year is that there will be mosquitoes. There always are,” said Mark S. Buffone, entomologist with the state Department of Agricultural Resources.
A mosquito bite can be a serious matter, as it may transmit disease to its human victim, an infection picked up from something else it bit. However, spring mosquitoes are generally “not a cause for concern in terms of disease (but they are an) annoyance and nuisance,” Buffone said.
August and September are the peak months for mosquito-related illnesses, such as West Nile virus or eastern equine encephalitis, he said.
West Nile virus, present in Africa since the 1930s, was first detected in Massachusetts in 2001, two years after it was first seen in the United States. Most people who are infected exhibit only flu-like symptoms, but a small percentage die from the illness. Since 2001, about 60 human cases have been reported in the state and six deaths have been linked to the virus. There were seven human cases of West Nile virus, but no deaths in Massachusetts in 2010, including one case in Hampden County.
Eastern equine encephalitis is more rare, but more deadly. It kills about a third of the humans it infects. However, no human cases of the disease have been reported in the state since 2008. From 2004 through 2006, there were 13 cases, which led to six deaths.