- German cockroaches have risen in volume for the industry in recent years.
- For bait-only cockroach control, there are two easy-to-diagnose baiting errors.
German cockroaches (Blattella germanica) are forging a comeback, and infestations are becoming larger and more numerous. Many companies continue to rely on a bait-only strategy for cockroach control. If you get control in a week or two, you’re doing it correctly. But if it’s taking months and you’re still only “keeping a lid” on the population, you should rethink your strategy.
There are a number of reasons why a bait-only strategy doesn’t eliminate cockroaches quickly, but two of them are embarrassingly common:
1. YOU DIDN’T APPLY A SUFFICIENT AMOUNT OF BAIT.
Previous studies have shown a German cockroach will eat approximately 1 to 3 milligrams of bait. If you do a little math, the typical 33-gram (33,000-milligram) bait tube, if evenly fed to all the cockroaches, could be good for about 10,000 cockroaches. Ideal conditions, however, don’t occur in any account I have ever seen.
With this as your rule of thumb, a single tube could handle a significant population — but won’t get you there for a monster infestation. If the population is epic, start with a vacuum cleaner and reduce the population quickly. After that, you should expect to find the majority of your bait gone within three to five days. If you find all your bait is gone in the areas of activity, you didn’t use enough. Remember, bait is not expensive, but callbacks are.
2. YOU USED A BAIT THAT COCKROACHES WON’T REAILY EAT.
Bait aversion builds over time within a population. In the early stages, it is difficult to tell the difference between bait aversion and poor technique. If the bait is placed in the areas of activity, but bait consumption is slow, this is a sign that bait aversion has been building.
Validate your bait before you even apply by offering it to cockroaches in their harborages during a pre-application inspection when you’re putting out insect monitors. If the cockroaches come and eat your bait while you’re watching, you have a winner. If they sit there waving antennae at you, but no one ventures out of the dugout, you need to try a different bait.
There are other reasons why bait-only programs underperform or fail entirely, but they are usually connected to either baiting techniques or human behavior. We haven’t discussed gravid females with egg cases that don’t feed much for several weeks, either, but cockroaches do come out every night to feed. If you start with a bait they can’t wait to eat — and put enough of it in the right locations — you will get sparkling results.
You can reach Mark Sheperdigian, BCE, vice president of technical services, Rose Pest Solutions, Troy, Mich., at email@example.com.