I inspected a home in Oceanside the other day. When I arrived, the homeowner proudly showed me all the products he’d used over the past twenty-plus years—Terminate from everyone’s favorite home improvement store, a few organic options, and some other odds and ends. I’m not sure why DIYers always feel compelled to show me what they’ve tried, but they always do.

They also walk me through every spot they thought was infested. I get the sense that some of them would be perfectly happy if I agreed with their assessment and skipped my inspection entirely. Of course, I didn’t. I conducted a full inspection, crawled both attics, checked the outdoor closets, and probed all the exterior wood. Despite their vigilance, I still found termites in more than twenty additional areas.

So how does that happen? How can two attentive homeowners—people who clearly care about their house and actively look for termites—end up with far more activity than the average homeowner?

Simple. They did it themselves.

Now, you might be thinking: Of course he says that—he wants to stay in business. So let’s set aside the fact that I’ve inspected over 5,000 homes, completed hundreds of treatments, passed multiple licensing exams, read more books and articles about termites than I can count, and logged hundreds of hours of continuing education to maintain my licenses. Forget all that.

DIY fails for one main reason: homeowners use the wrong chemicals.

I won’t use the industry term “repellent,” because that’s misleading. Who wouldn’t want to repel termites from their home? The issue is that DIY products kill on contact and termites can detect them.

What’s wrong with that? Think about ants. You see a trail, you spray Raid, you kill dozens… and they keep coming. Why? Because you’re only killing workers, and the queen replaces them faster than you can spray them.

Termites work the same way. Workers chew the wood. Workers forage. Workers die. The queen makes more—thousands over her lifetime. Some termite queens live up to 30 years.

Unless you eliminate the queen, your problem doesn’t go away. In fact, it often gets worse. The termites that don’t die from DIY products can taste and smell the chemicals, so they avoid them, retreating deeper into inaccessible areas of your home. Meanwhile, the queen will eventually send out swarmers to start new colonies. You may never even witness it—it could happen quietly in your attic, wall voids, or other hidden spaces.

Professionals use non-detectable products. Termites can’t sense them, and they don’t kill on contact. That’s intentional. Workers have time to carry the product back to the queen and the rest of the colony. These treatments also stay active in the wood for years, providing long-term protection.

Good termite inspectors are willing to drag themselves through tight attics and crawl spaces and use long poles to probe second-story eaves. Responding only to obvious evidence is not a strategy. A second-story rafter tail can look perfectly solid until my probe touches it—and suddenly it’s a piñata full of termite droppings.

If you own a home in California, you’ve basically won the lottery. Over time, that home will be worth far more than what you paid for it. Protect your lottery ticket. Hire a professional and have your home inspected and treated regularly. The money you think you’re saving with DIY will eventually cost you double or triple in wood repairs, hotel stays for fumigation, and more extensive termite treatments down the line.