I have used this product for 2 years in the summer months. It effectively controls the flea outdoors. Our neighborhood is home to numerous feral cats and there are about 8 the come to my back yard that I feed. Before I used this product, I could literally see the fleas hopping from the ground, walkways and all over the outside of my house. At one time, I look down on my bare legs and literally had dozens climbing up my legs. that sent shivers down my spine. I decided to try the Bayer Complete Insect Killer that year and behold, after a couple of days, all the fleas were pretty much gone. even the oudoor feral cats were scratching less. I've been using this produce in the hot summer months and it has been a success. I live in California where the summers are dry so I don't have to reapply.