Answer
Aug 26, 2025 - 09:21 AM
There are a lot of variables that you haven't mentioned. Location, location, location is number #1. Outdoor cockroaches such as Smoky Brown, American, Oriental, etc are most commonly associated with natural environments such as heavy landscaping, woods, creeks, marshes, debris fields etc. Non-natural sites such as sewers, swimming pools, etc can also attract them. This time of year, they will migrate indoors. This is due to their population size, also survival and breeding instincts. If you are finding them indoors, then there is a reason why. If you are using Bifen and Niban as you stated, then part of the issue may be that you are not using it often enough or even strong enough.
My advice is to treat the entire lawn area or at least more than 2-4 feet away from the house. Pay special attention to areas where they can hide and breed. Niban Bait may not be the most effective for these cockroaches either. While it is a good product, it takes time to work, usually 1-2 weeks or more. Using glue traps such as the Trapper LTD can also help. Place these under and behind furniture, etc. Using an insecticidal dust such as Delta Dust applied into plumbing and wall voids, under bathtubs, etc, can also be helpful.
The most important thing is to keep applying these products frequently enough so that they stay effective. In the summer, Bifen IT may only be effective for 1-2 weeks or less depending on heat and rain, moisture etc. Reapplication of these products is key to continued control. Seeing a nymph every now and then indicates that breeding is close by. Usually very close. You may be missing the breeding spot. It could be under the bathtub, it could be in the sewer / drain pipes. These insects can easily enter your house from around toilet rings, inside plumbing lines (crawl from the sewer pipers in the street), etc. Hope this helps.
My advice is to treat the entire lawn area or at least more than 2-4 feet away from the house. Pay special attention to areas where they can hide and breed. Niban Bait may not be the most effective for these cockroaches either. While it is a good product, it takes time to work, usually 1-2 weeks or more. Using glue traps such as the Trapper LTD can also help. Place these under and behind furniture, etc. Using an insecticidal dust such as Delta Dust applied into plumbing and wall voids, under bathtubs, etc, can also be helpful.
The most important thing is to keep applying these products frequently enough so that they stay effective. In the summer, Bifen IT may only be effective for 1-2 weeks or less depending on heat and rain, moisture etc. Reapplication of these products is key to continued control. Seeing a nymph every now and then indicates that breeding is close by. Usually very close. You may be missing the breeding spot. It could be under the bathtub, it could be in the sewer / drain pipes. These insects can easily enter your house from around toilet rings, inside plumbing lines (crawl from the sewer pipers in the street), etc. Hope this helps.
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