If you're using our bee viewing blocks, the short answer is yes! If the mother bee is home when you do this, see will often freeze up and not move, or will quickly fly out the front. While we have never had an issue with one stinging while handling a bee block, be careful as it is possible. If instead you have our regular bee blocks, there's a bit more nuance: First, if your bee is a leafcutter bee, then opening the nesting block while the nest is under construction is most likely safe. You will simply see each cell wrapped in pieces of leaf. If, however, you have mason bees or another species that makes their cell walls out of mud, resin or another brittle material, this could potentially be destructive. Until the egg has had some time to develop, it is very fragile, and opening it may result in a wall collapsing and destroying it. Once it has developed for a number of weeks, this concern is reduced. If you decide to leave your blocks in the home year round, we do not recommend opening it after the mother bee has sealed off the front, as this could allow parasites in. However, if you can set it aside somewhere safe, you can open it after a few weeks with low risk. In general, be very careful when viewing a nest while it is being constructed. We want the bees to be safe and make it to adulthood, after all!