You do not specify what pest you are concerned about, but you might consider an insect growth regulator, such as methoprene, for fleas. This active ingredient comes in a variety of formulations including collars, sprays and mousse. Check with your vet for safe treatment for on-animal treatment of ticks and heartworm (transmitted by mosquitos).

Many of the kennel sprays might be used safely if allowed to dry thoroughly before reintroducing the puppy to the outdoor area; but as a rule of thumb I would avoid any use of insecticides until the puppy gets a little older (how old? check with your vet). Spot treatment of suspected harborages around the yard, without a broadcast treatment of the ground and grass, might be a good compromise--especially for ticks. Until the puppy get older, just be more aware of pests and treat only as needed. For more information see our publication at http://dallas.tamu.edu/insects/FastSheets/Ent-1002.html