They can be applied with a watering can or a sprayer. Water the greenhouse well before releasing nematodes in the morning, evening, or on a cloudy day. You can keep the undissolved agar containing dormant nematodes in a refrigerator until needed. Predator mites arrive ready to be released and should be seen with a hand lens walking on the top of the container. Cool temperatures slow down the development of insects, so a refrigerator will give you a little time if you need to delay release.
Warm temperatures speed up development, but high heat can kill.
I have had an entire order of predator mites die from being left in a mailbox on a hot day. In addition to biological controls, there are several insecticides that I have used in the greenhouse with success. They include BtI, soap, oil, botanicals, including pyrethrum, and insect growth regulators. These, combined with biological controls and preventative measures in a coordinated system of integrated pest management, should give you all the edge you need in dealing with pests in the greenhouse. After every step in the program remember to evaluate the effectiveness of the choices youUve made and see how close youUve gotten to your goals.