With the increase of aggressive and dangerous fauna, the Bee Empire had to send more and larger border patrols to prevent them from entering the Empire and breeding there. To support them logistically, I ordered building a lot of military forts, and even lay railroads toward them for easier delivery of resources.
The forts were essentially just work camps. Their defenses were only slightly stronger than on average—they just had some ballistas in place to shoot off anyone who approached without permission.
This was because our enemies didn't care about fortifications, anyway. They either ate bees, or were mindlessly looking for other food, while attacking in retaliation against anyone who stood between said food and them.
The price in time and resources that the Empire paid to build new forts every time our borders expanded was nothing compared to the increased safety.
