Comment by OneDeuxTriSeiGo

It's not that it eliminated mosquitoes entirely but rather that it effectively eliminated mosquitoes in the genus Aedes.

These are some of the most problematic/disease causing of the mosquitoes but also notably mosquitoes in the Aedes genus are essentially the only mosquitoes that are "hunting" during the day. All the other mosquitoes operate almost exclusively in the evening and at nighttime.

So by eliminating these mosquitoes a major disease vector is eliminated but at the same time it completely eliminates mosquitoes during the day (i.e. the main time when you are out and about trying to enjoy the summer).