Pesticide drift is the movement of a spray solution from the intended target to a place where it is not wanted, or the movement of spray droplets or pesticide vapors out of the sprayed area. In particular, herbicide spray drift can damage shelterbelts, garden and ornamental plants, cause water pollution, and damage non-susceptible crops in a vulnerable growth stage (2,4-D drift on wheat in the flowering or seedling stage, for example). Herbicide spray drift can cause non-uniform application in a field, with possible crop damage and/or poor weed control. In addition, insecticide spray drift can damage beneficial insect populations especially bees and natural predators of Montana agricultural pests. Drift is also costly from a financial standpoint. If only 50 percent of an applied solution makes it to the target, then you have wasted 50 percent of what you have applied. In all the above cases, the pesticide becomes an environmental pollutant, injuring susceptible plants, contaminating water, wildlife and even humans. Sadly, the majority of pesticide spray drift problems involve mistakes that could have been avoided by the applicator.