By: Dr. Cisse W. Spragins
German cockroaches have a relatively rapid rate of reproduction and are very persistent in certain types of accounts. For this reason, they can develop resistance fairly quickly if the same control product is used over and over. Resistance can be to a certain active ingredient or, as we have seen in recent years, to particular inert or food ingredients in baits. This form of resistance is called “bait aversion” — the roaches won’t eat the bait.
To prevent bait aversion and other forms of resistance from building up, it is imperative to use different treatment methods. At a minimum, gel baits should be rotated three to four times a year. It is important in the rotation that gel baits that differ in both active and inert food ingredients be used; otherwise, the rotation won’t do much good.
For the best results, other control methods should also be used. Boric acid dust is a good, non-repellent choice in areas that are not readily accessible. In damp areas, pipe chases and sewers, weather-resistant borate granular bait is a great choice. In areas that don’t see a lot of moisture, residual sprays can be used.
It is important to be mindful that pyrethroid sprays are repellent, so they should not be used in the same area as baits. For periodomestic (outdoor) roaches, perimeter and/or infested area treatment with granular bait is a great option. For lasting protection, a weatherable borate granular bait should be used, because this will hold up longer than other baits — and longer than most sprays, particularly on natural surfaces.
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