If there is any connection at all, I think it would be a pretty weak one. Grasshoppers don't eat mosquitoes and mosquitoes don't (I think) feed off grasshoppers. However, these critters are quite sensitive to the weather: lots of rain favors mosquitoes and dry hot weather favors grasshoppers. A lot of little critters also have a cycle. Tent catapillars around where I live are on an eleven year cycle. In the valleys of the cycle, you won't see a single one all year. In the peaks, there is enough to defoliate large trees.
Especially if there was a cold winter the year before. I remember talking to an orchard worker who lamented how the frost came early and killed a lot of the fruit before they could be harvested. He said "At least there won't be any bugs next year!" and it really opened my eyes to how these cycles can work over such extreme swings.
