Insects form the basis of prey for many species including bats and birds. Broad spectrum white light or light with a high ultraviolet content can 'hoover' up to 75% of the insects from a habitat -the so-called 'vacuum effect'. Around a third of these insects will die.

To read more on this subject there is a Yahoo Group  https://groups.yahoo.com/neo/groups/lightsandwildlife/info