The removal of nearby female boxelder trees is one of the most common solutions for repeat boxelder bug infestations. If you choose to pursue this path, be sure to also remove any seeds from the tree that may have fallen onto the yard. This method is not guaranteed to fix the problem, as these bugs are known to travel as far as a mile in search of food and shelter, but it can help lessen the likelihood of infestation.
Insecticides are generally not recommended in the treatment of boxelder bug infestations, as these insects do not maintain their colonies inside the home. Instead, individual boxelder bugs can be either vacuumed up or killed with a detergent-based spray. Exclusionary measures--including the sealing of cracks and crevices, especially around windows, with either caulk, spray foam or copper mesh--are also strongly recommended.