Roaches Gotta Eat

Wednesday July 18, 2012


Mr Pest Control


I have a friend with a custom car building / mechanic shop which is a large place, equipment around the walls, car lifts, etc. With the restrictions we have now how would you go about treating a shop like this for roaches? In the past I have treated around the base of the walls as much as possible, under equipment the best I can, and spot treated around the doors and any possible entry points. Mainly I see American and Australian roaches and there are no moisture issues that I can see. There is no break room so no feeding area or water resource. There are two bathrooms just off of the shop which I treat. The way I have treated in the past has worked just fine, and just wondering what your professional thoughts are.

Steve, FL

Mr Pest Control


First, I guess, is that I don't know of any new restrictions on the use of insecticides indoors for a site like this. You may be referring to the new label changes on synthetic pyrethroids, but these only address outdoor settings and refer to restrictions in using these products on exterior surfaces of the structure and on "impermeable" horizontal surfaces such as patios or sidewalks. I don't think these changes should have much effect on how you would treat for cockroaches, either inside or out. This, however, doesn't necessarily mean that what you are doing or have been doing should not change in some way. If it is not currently fixing the pest problem then continuing it would seem to be a poor course of action. 

I personally believe that just about any of our currently popular cockroach products is going to kill cockroaches. The key is getting the active ingredient and the roach together for a long enough period or time, and this is referred to as "contact time". The a.i. must be given the opportunity to get inside the roach in concentrations high enough to kill it by affecting its nervous system, or in the case of boric acid baits to be eaten in sufficient quantities. A quick run across a dry deposit of insecticide by a large cockroach is really unlikely to achieve this contact time, and for this reason I am not a great fan of baseboard treatments or other surface spot treatments. Much better for roaches found indoors is to take the fight directly to where they spend 80% of their time, and that is hidden within crevices, voids, and beneath materials resting on the floor. Placing the active ingredient directly into their harborage maximizes the contact time and also puts that material where other roaches may choose to hide if they enter. 

One IPM step that could be offered to this account would be storage of materials off of the floor, perhaps on metal racks as much as possible. Removing that harborage opportunity limits what is left so you can treat it more easily, less roaches can live inside with the reduced hiding places, and you put those present under stress because you have taken away one of their needs. 

Now, whether or not you know of any food or water resources we have to recognize that these roaches are, indeed, eating something. Perhaps their foods are outdoors and they are just using the interior for harborage during the day. Perhaps there are foods inside that you have not discovered or your customer has not revealed to you. Presumably the people who work there do eat lunch at work occasionally, so something may be discarded or fallen and forgotten. Ditto for the moisture, and Australian roaches in particular require high moisture in their environment. Of course, you are in Florida, so humidity is high anyhow, and with all the recent incredible rain you have had it may be that much higher. This also may be a reason these roaches have moved indoors more to escape excessive water outside. 

I would take a really close look around the exterior to see where these roaches may be coming from, since they often are outdoor roaches. There may be opportunities to change conditions outside to remove food and clutter that support them. You also might try granular insect baits outside and even inside with a bait labeled for the interior. Large roaches seem to like this kind of bait and eat it readily, particularly if other foods are removed or restricted. Take a look at any voids inside such as wall voids that connect to the exterior, as the roaches may live within them and they could be treated with a contact dust. Take a close look at where you can fill in openings on the outside that the roaches may be using for entry, and seal those permanently where possible. 

Mr. Pest Control

Register now for PestWeb to get instant access to all of Mr. Pest Control's in-depth answers!

Register Now Ask a Question Add to My Favorite Questions

Please note, Mr. Pest Control is answering questions supplied by PMP customers across North America. His answers are generated from industry and manufacturer-provided information. The answer may not be specific to the laws and regulations for your State, Province, Territory or Country. In addition, products mentioned may not be registered and or available in all areas. Always check with your local Univar office for specific information to your area. Always read and follow label directions.