I'm going to correct the people here. And I won't quote.
Nipah- Frogs are carnivores. They not only depend on mosquitoes, they depend on other organisms as well. Large frogs eat smaller frogs and small turtles while a smaller frog would eat bugs and worms. So, the population of frogs won't dramatically decrease. This applies to spiders as well. They can feed of other insects. But the animals would have more competition since the mosquitoes are gone. Then the same goes to birds. There would just be more competition with food but the population won't decrease. They'll adapt. We won't disappear.
Jackbluejack- Frogs can live off other things.