The high temperatures hitting the Sierra Nevada have led to an unexpected surge in the mosquito population just in time for the peak summer tourist season. The area has witnessed an explosion of snowmelt mosquitoes, an assortment of half a dozen highly aggressive species that hibernate beneath the ice and emerge to feed as it melts. However, this year’s boom is happening later than usual due to the record-breaking snowfall in the spring and the late start to the snow melt. Typically, these mosquitoes emerge gradually throughout the spring and early summer. But the sudden temperature change this year has disrupted their usual pattern, according to Joel Buettner, manager of the Placer Mosquito & Vector Control District.