âÂÂIn the greenhouse, the convergent ladybeetle, Hippodamia convergens, feeds on aphids and spider mites. Ladybugs do not always provide successful, long-term control but they are useful to "knock down" an infestation. â¦Ladybugs can be stored in the refrigerator for several weeks and released one handful at a time. They are usually thirsty when released, so plants should be misted prior to release. Releasing them in the evening is also important.âÂÂ

Here is a link that might be useful: ladybugs in the greenhouse