1. Not enough to feed on
Yes, if an insect predator like Ladybugs, Lacewing or Praying Mantis do not have enough food (insects) in your yard they will move elsewhere to find them. This is something that is out of your control since you definitely don’t want to purposely infest your yard with aphids!
2. Not enough cover
Having shrubs and trees in your yard, particularly evergreen, provides shelter from birds, wind and rain.
3. Too many insecticides
If you have a pest control company spray regularly or you spray your yard on a routine basis you are probably killing beneficial insects.
So if you decide to release Ladybugs or Praying Mantis in your yard which one do you choose? Part of it is preference but personally I recommend Praying Mantis. Yes, Ladybugs are pretty but short lived and very flighty. Praying Mantis will stake out territory in your yard and defend it to the death.
So that’s my two cents about beneficial insects. Any comments or questions? I’d love to hear them!