There are three important factors that allow mosquito control applicators to target mosquitoes while having a minimal effect on other organisms. These include the way insecticides kill, the amount of insecticide sprayed and the time the insecticide is sprayed.
First, modern pesticides have become more specific as to what they will affect when used in the correct amounts. For example, pesticides that kill only insects, affect parts of the insect that other animals and plants do not possess. Just as rat poison, when used in the proper amount, does not kill insects and weed killer does not kill birds, mosquito pesticides, when used in the proper amounts, do not kill birds or rats. Most of the pesticides used to kill mosquito larvae have minimal effects on other organisms.
Second, the amount of pesticide, or dose, is an important factor. The pesticides that are used to kill adult mosquitoes can, and do kill certain other insects, particularly those that are similar to mosquitoes, such as blind mosquitoes, no-see-ums (biting midges), and other small insects. They do not kill larger insects like house flies, butterflies, horse flies, or beetles because the dose applied is not high enough.
Third, while some insecticides used to kill adult mosquitoes can kill bees, they are not used during the day when bees, and many other insects, are flying around. They are used at dusk or at night when the mosquitoes are flying and the bees are not. That's one reason trucks do not spray during the day.