Feed them with wheast to encourage them to stay in the greenhouse, especially if you have a very low pest population. Lacewings arrive as eggs and often hatch a few days later. You want to release them as soon as they hatch. A hand lens can help you determine when hatching has finished. If you wait too long, they will eat each other.
Nematodes come in an agar base that needs to be dissolved in water.
You should be able to see them swimming around with a hand lens. 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.