How would spraying a yard with chemical pesticides to control insects be most likely to affect the diversity of insects found in it?

There would be fewer harmful insects and more beneficial insects in the yard.

Pesticides are chemical or biological substances which are added to reduce or prevent the growth of insects or pests in a agricultural or garden field. The action of a pesticide will be specific to the target pest and may not cause harm to desired species like pollinators. On spraying a yard with chemical pesticides to control insects will result in fewer harmful insects and more beneficial insects in the yard if the action of pesticide is specific to the harmful targeted pests.