Tis the time of year when outside critters start looking for cozier places to be for the coming winter, and they respond to conditions such as shorter daylight hours, cooling temperatures, or the initial rains of the season. Millipedes are capable of living for several years, even up to 10 years for some large species, so they need to survive a number of winters. We often see the opposite reaction from them too, when large numbers of millipedes may migrate out of natural habitats as those places dry in the hot summer, forcing the millipedes to look for damper, cooler, greener places to live and feed. Dramatic changes in the weather are often the cause of these kinds of movements toward and into structures.
Thus, for a real shot at long term control the customer needs to be brought into the program too. They should understand that the reason these millipedes are now inside their home is not to find food resources, because the interior of a structure is not really conducive to their survival, but only to find a place to overwinter or to escape some weather changes outside. And, the reason the millipedes were able to get to the structure in the first place is because they were provided good conditions outside or the past many months, and we will refer to those as "conducive conditions" - those conditions such as the presence of harborage in particular, that allowed the millipedes to survive and multiply on this property. This becomes worse when harborage is provided for them right up against the structure, such as thick grass or groundcover or shrubbery that they hide under. If branches are touching the walls or the roof then it provides an easy pathway for these and many other critters to climb up to entry points above.
So, we'll get to the insecticide part of this eventually, but here is an opportunity for you to help the customer for the long term. Advise them on the conditions you find around the exterior that can be eliminated or minimized so that millipedes do not live on the property, and in particular not adjacent to the structure. Plantings should be removed to leave a moat of bare ground 2 feet wide, if possible, or at least soil covered with gravel or rock rather than mulch or bark. Anything piled against the exterior walls should be moved away or at least stacked up off the soil to eliminate the moist, dark environment the millipedes need for hiding during the day. Areas surrounding this property should be examined and managed if possible to remove harborage, since the millipedes on this property originated from areas around it. Anything you can achieve non-chemically like this will help to reduce the population of bugs on the property and thus reduce the pressure for them to enter the structure, and finally to reduce the reliance on toxic materials.
Exclusion should also be examined, and again this is an OPPORTUNITY to make more money (get paid for your time) while serving the customer better. Look for all unnecessary openings around the exterior and permanently close them with the appropriate material, whether it is wood, door strips, weather stripping, caulking, copper or stainless steel mesh, expanding foam, etc. Every opening you can close eliminate one opportunity for the bugs to get inside easily, and now you can apply your insecticides in a much more directed manner to the remaining points of entry.
There are so many excellent residual products available now that I suspect the industry is using dozens of them effectively, but most effectively when the steps above are undertaken first. Granular contact products like Talstar or DeltaGard granules can be applied around the perimeter, with a good look at applying them to areas in the landscape where you need to be able to get the product down through cover, such as bark or rock or ground covers. Microencapsulated formulations, and there are many of them now, are good choices for treating around the perimeter of the foundation, as these hold up longer when exposed to the weather and they offer a good chance for adhering to a passing millipede as it crawls to the base of the structure and starts the trek up the wall. It will be a lot easier to kill them on the outside than inside once they make it into the attic or the wall voids.
On the interior the millipedes that are seen should be vacuumed by the homeowner and not allowed to die and lay on the floors. These arthropods tend to "leak" out some body fluids that may cause staining and spots on the surface. Otherwise they are essentially harmless as long as no one puts one in his mouth. They do use some pretty noxious chemicals for their defense.
Mr. Pest Control
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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.