How long will my termite spray last?
There's no simple answer for this one. Probably more than two years. Some sprays, like chlorpyrifos can degrade very quickly. Others such as bifenthrin and fipronil will last longer. Imidacloprid is somewhere in between. The rate at which a poison degrades varies enormously over short distances. The main factors are: the initial dose applied, temperatures, rainfall, soil type, alkalinity, presence of plants, applicator skill and the chemical properties. Then there's disturbance from floods, gardeners and burrowing animals. The chemicals will last a lot longer under your house than around it. With the same chemical, you might get ten years or more under the house but only two to five around the outside. Some poisons, like imidacloprid, can be happily sucked up by plant roots so that while you might have no aphids on your roses for a while, there's a risk the poioned-soil barrier mightn't last as long as you'd hoped. You'll note I used the chemical names rather than product names. There's also likely to be variation between products with the same chemical poison but different formulation. Even the difference in the size of the tiny particles of poison can make a difference. You can get your soil tested to see what's there or you can rely on the experience of your pest manager to tell you when another dose is needed. Try not to over do it.