Humidity levels in your container go hand in hand with proper ventilation. It is quite easy to monitor the humidity in your container by checking to see if there is condensation on the sides of the box or if the housing (egg cartons) is damp, droopy or can tear easily. If any of these are the case in your cricket container than it is too humid. Ideally you want to aim to keep the humidity level below 75%, which can be done by making sure you have proper ventilation. Although not a necessity, if you are worried you can purchase a digital hygrometer for a few dollars which will allow you to accurately check the humidity in your container.