I dunno...
I took a vacation to Utah 2 years ago. NO mosquitos, lots of bats. Here in Connecticut we have lots of mosquitos, few bats. Maybe he means the Texas bats don't eat mosquitos.
I think a more likely reason for the disparity in mosquito populations is that Utah is a lot dryer than Connecticut. Insects thrive in wetness, laying their eggs in stagnant standing water, and are at their worst when humidity is higher.