One of the atmospheric touches early on in Interstellar (no spoilers, I promise) involves Cooper (Matthew McConaughey) and his kids chasing a rogue unmanned aerial vehicle until they are able to take control and land it. They then cannibalize it for parts.
While there is not yet a flock of rogue drones wandering through the air, it’s reasonable to think that eventually some UAVs will crash in places where it won’t be so easy to recover them, in whole or in parts. Absent some spy-level self-destruct magic, one method of dealing with this future debris is to make it biodegradable.
One group working on this for drones is competing at the International Genetically Engineered Machine Competition (yeah, I didn’t know this was a thing either). They have found a company that uses mushrooms to form the bulk of the drone body. Using other natural materials, such as cellulose and proteins from wasp spit, the bodies of these drones are both biodegradable and water resistant.
Now, there are still several parts that are non-biodegradable, but work is proceeding on making biodegradable versions of sensors, rotors and other parts to make a completely biodegradable craft. Besides minimizing the environmental impact of crashing electronics in the wilderness, these craft can also make it harder for technology to fall into the ‘wrong hands’ – unless they get to the craft really fast.