There are lice and there are lice. Birds and rodents are frequently infested with chewing lice that do not feed on blood and are not going to attack people. The more likely lice in homes or on people are going to be our Big Three - crab lice, head lice, and body lice, and only one of these warrants any kind of insecticide treatment by a pest control technician, and this would be Body Lice. Head and crab lice are completely, 100% the role of a doctor to deal with by prescribing a medication or shampoo that will kill the lice on the people. These two species are unlikely to be found in the environment of the home, although this is not always the case. They stay on their host (people) but may be dislodged onto clothing, hats, bed coverings, or couches when a person with the lice comes into contact with those items. Then, a second person may acquire the lice if he or she immediately comes into contact with those items as well. These two lice lay their eggs on the host animal and both will die within 24-48 hours if they are unable to get back onto a person. Control is treatment of the infested areas along with laundering or hot drying of all clothing and other fabrics that may have the lice on them. 

Everything you read from reliable sources on crab and head lice tells our industry that we have no role in their management, and no insecticide applications around the home are needed nor would be of any benefit. Killing the lice and their eggs on the person as well as on personal items is what eliminates the problem, and some items may not be considered initially, such as bicycle helmets and other things an infested child may have been wearing. If this is head lice and on a child this needs to be addressed immediately to prevent the child from being kept out of school as well as to prevent the social stigma of a child infested with lice. Head louse infestations have a way of running wildly through elementary schools. 

If it is body lice then there may be some need to treat areas of a home. This species tends to remain more on the clothing, to lay its eggs on the clothing, and to move to the person only to feed before moving back onto the clothing. Control also should involve the same thoroughness of laundering in hot water and hot dryer any clothing that has been worn while the infestation was going on, along with all bedding and other fabrics that the lice may have gotten onto. Even a hot dryer cycle alone is going to kill all lice and eggs that may be on fabrics that you may not want to launder. If items are sent to a commercial dry cleaner the store personnel MUST be advised they are accepting potentially infested fabrics, so they can keep them separate from others in the facility until treated. 

There are about a dozen insecticides specifically labeled for Lice or Body Lice, and you can view this list on PestWeb in the Product Documents resource - choose "Products by Target Pest / Biting, Blood feeding / Body Lice". The list includes both residual products as well as contact products for fogging, but the emphasis should be around areas where the clothing is stored. This would be where lice may move off the clothing or eggs hatch and initiate movement of new lice. Emphasize the laundering and hot dryer, a thorough vacuuming of areas such as furniture, and treatment of the lice directly on the infested person using a prescription product. 

But, try very hard not to get talked into spraying insecticides around a home for crab or head lice, as it is unnecessary and would do little in the overall effort.