Physical control, also known as source reduction, environmental manipulation, or permanent control, is one part of the District’s Integrated Pest Management (IPM) program. Physical control is usually the most effective of the mosquito control techniques available and is accomplished by eliminating mosquito breeding sites or modifying these sites to favor natural predation or to be unfavorable to mosquitoes. This can be as simple as properly discarding old containers such as tires or buckets, or as complex as controlling salt marsh mosquitoes (Aedes squamiger and Aedes dorsalis) utilizing tide control structures and/or drainage ditches. The District performs maintenance on drainage ditches in tidal marshes primarily with hand tools between the months of September and January. Source reduction can virtually eliminate the need for pesticide use in the affected habitat. Source reduction is appropriately touted for its effectiveness and economic benefits.