Spray characteristics were investigated to determine the optimum aerosol spray for insecticides while considering volatile organic carbon (VOC) reduction. Our ultimate goal is to improve the efficiency of killing insects while using less aerosol spray, which contains chemicals, oil, and dimethyl ether (DME). Most of the oil and propellant fail to reach the target, and fall to the ground. The propellant is used to break droplets into smaller droplets and to carry them to the target. Most of the propellant's energy is used for carrying these droplets, although the remaining droplets are very small compared to those produced at the nozzle. We investigated the droplet characteristics over the entire distance from the nozzle to the target. Here, we tested different nozzle dimensions and compared single- and double-hole nozzles. We measured the spray characteristics near the nozzle to evaluate the droplet-forming process by examining droplet separation, agglomeration, collision, and size to elucidate the spray behavior and determine the dominant factors involved in designing and developing a nozzle for spraying insecticides most effectively. The key factor for developing the optimum nozzle for spraying insecticides is not the number of holes or nozzle diameter, but the agglomeration process and the amount at the target distance. The key to developing a system that decreases VOC dramatically is how the droplets are generated at the nozzle. Droplet diameter and velocity when exiting the nozzle need to be understood quantitatively and controlled; the most important considerations are to maximize spray agglomeration, in order to deliver droplets with an effective diameter to the target, and to reduce the number of oversized droplets failing to reach the target.