Q.eucalyptus tree losing large chunks of bark
I would like to know if it is normal for a eucalyptus tree to lose large chunks of bark? Very mature tree. We have 3 and they are all having the same problem.
There are over 700 varieties of eucalyptus, and you'd need to provide the name of yours for us to get an idea of what is normal of that tree, but it is true that most eucalyptus shed bark. Many don't start to shed until a certain age has been reached. When you say very mature, again, more exact information is needed to make an informed suggestion. Here are a couple of articles on eucalyptus: https://www.gardeningknowhow.com/ornamental/trees/eucalyptus/tips-growing-eucalyptus.htm
https://www.gardeningknowhow.com/ornamental/trees/eucalyptus/eucalyptus-tree-problems.htm
If after reading the articles you think there might be a problem, you could take some samples to an expert to see if it's simply old age, of if there are measures you can take to save your trees. You could call in a certified arborist, talk to people at a good nursery, or visit the county extension service. I would advise doing the latter. This link will help you find the nearest office:
https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm