WOULD BUYING LADYBUGS AND PLACING IN A GREENHOUSE BE OKAY TO HELP WITH APHIDS
Buying Ladybugs for the greenhouse is a very good idea. Just make sure you buy from a reputable source that sells the American Lady bug, genus Hippodamia, and not the Asian Ladybug, genus Harmonia.
The Asian Ladybug is larger, more round shaped and very aggressive. They can swarm together in large numbers in the spring and fall. Sometimes by the thousands. If they swarm around your house, many will land on you and they bite. They also invade peoples homes and businesses. They have become an invasive species.
American Ladybugs are more oval shaped, are not aggressive, They do not swarm or invade your home and most of all, They Do Not Bite!.
Do you want them to keep from getting aphids? If you don't already have aphids, and you add the ladybugs, they will most likely die because they will have nothing to eat.