Quiz: What Is Used To Control The Behavior of the Deer in My Backyard, Many of My Dear Friends, and Me?

We've had a run of some pretty serious stuff over the past few weeks -- death and dying, death panels and regulating healthcare tests and procedures, our debt crisis, and the future of Social Security and Medicare.
So, let's take a break for a silly interlude. See if you can come up with an answer to the question above.

Background Clues
Even though we live in the city, our Palisades neighborhood has deer in abundance. I've seen as many as five together in my backyard. It's always a lovely surprise. But it's not so lovely when the hostas get eaten up, and my young serviceberry tree trunk gets mauled from male deer rubbing their antlers against it.

My backyard ends with a hill that goes down to my neighbors' fenced-off swimming pool. The deer like to sleep in the protected patch at the bottom of the hillside. When they wake, they head up the hill and into my backyard for food and frolic:

After snacking on hostas, she takes a rest. This picture was taken in June. A month later, the hostas are bare stalks.

After climbing the hill into the yard, the deer take this path (photo below) to exit. In late summer, the males pause to scrape their antlers against the trunk of the serviceberry tree to rub off the velvet on their new antlers. (The serviceberry is on the left of the picture below.) In November, the males come into rut and work off their pent-up aggression by scraping their antlers against the tree.

But now something has changed these behaviors. My hostas aren't being devoured and the serviceberry tree no longer shows signs of antler damage.  Here's a clump of hostas in early November, where only stalks would  have appeared  two years ago.

So, Why the Change? 
The same thing that changed yours truly from a drunk who ended up in jail more times than he'd care to remember. Fortunately, I don't have any "before" photos to show. But here he is today:

The Answer
I'm sure some of you, particularly my fellow recovering alcoholics, will have guessed the answer. My Bartlett's tree and garden contractor has used a spray on my yard for the past two years that's been surprisingly effective. I still see the lovely deer strolling through my yard, but they no longer stop to feed.

I was talking to the guy who sprayed my yard a few days ago and told him how well the spray worked. I was surprised when he told me that the chemical ingredient in the spray was the same as in Antabuse, the pill alcoholics take to help them stay sober. If the deer munch on plants that have been sprayed, they are repelled by the taste. If an alcoholic drinks after taking Antabuse, he gets very sick.

Here's the healthy serviceberry tree yesterday -- such a beautiful day! -- with its reddish-orange foliage above the red Japanese maple: