Hi Sir or Madam,
It sounds like your dog is bored. Younger dogs are more active than older dogs and thus have different requirements than the older dogs. They usually require more exercise as well. It might also be separation anxiety, but that does tend to be more consistant than you are seeing. I'll go over it anyway since many of the same technique should still help with a bored dog as well.
The first thing is to take your dog for a nice long walk before you leave, preferably 30 minutes or long. Make it a long, quick paced walk to tire your boy out.
Second is to use a low-key approach to leaving the house. Ignore your dog before you leave and after you come home for at least 5 minutes or more. If your house is like mine in the morning everyone is running around getting ready to leave. This has the dog in an excited mood and then suddenly he is alone. If this is the case, put him away from everyone, say in a bathroom until the frenzy is over.
Don't punish or shout at your dog when you come home and find he's destroyed something or gotten into stuff he shouldn't have. When you do, you increase his stress level rather than reduce it.
You can provide him with small stimulating toys or toys that you can fill with treats. One I find that is very effective is the Kong which has a compartment that can be filled with treats. I have found filling the compartment with peanut butter and freezing it before giving it to the dog can keep a dog busy for hours on end. Large knuckle bones are also good for keeping a dog busy and are pretty safe for a dog to gnaw on.
Sometimes leaving a TV or radio on can help a dog with this problem as well. Recording the sound of the humans moving through the house and played on a tape or computer may also fool the dog into thinking you are home. Also remember to not reward a dog's excitement to you with petting and affection or even eye contact. You want to show him nice calm praise when he is being calm.
You can also try practicing alone time by having him spend time away from you in a crate or other area away from you for short periods of time when you are home.
These should help his separation anxiety and boredom and help curb his destructive behavior. It will not be an overnight cure and will take work on your and your family's part to be consistent in your interaction with him.
Another option is medication, which is discussed on this site:
Of course, crating him while you are gone or containing him in a room that has been dog proofed will also prevent the desctruction. Many owners crate their dogs when they leave them at home. Some are crated for up to 8 hours at a time with no ill effects. It actually would be in his best interest if he may be consuming foreign objects during his destructive phases.
Hope this works for you.