 Yellow jackets are a common problem in schools, however there are many other insects that are often mistaken for yellow jackets, such as honeybees, beneficial surfeit flies, and the paper wasp, a much less aggressive wasp than the yellow jacket. Before starting any management program, make sure you really have yellow jackets and not one of these other common insects. Become familiar with the seasonal patterns of yellow jackets so that you will know the best time to take action. Patterns emerge between April and May, and workers begin foraging late spring into summer. Yellow jackets reach their peak in August through late September. Yellow jackets feed on sugars and protein. Proteins are mostly favored during the spring and summer when larvae are developing. Sweets are favored in the fall. An essential component of a yellow jacket IPM program is prevention. But attractive food sources, such as sugar drinks, grease, and protein, at a minimum. Prevent yellow jacket activity as much as possible, especially around dumpsters, trash cans, and recycle bins by using liners, lids, and cleaning them daily. Seal holes in foundations, walls, roofs, and eaves. The most effective way to manage yellow jackets is to look for their nests and treat them. Nests are in the ground and have lots of yellow jackets coming out. If you find one, keep children away, and have it treated immediately by your local mosquito abatement and vector control district, or a licensed applicator. In some cases, traps may reduce numbers of wasps but are not nearly as effective as treating nests. Most commercial traps contain a chemical to lure the pests into the trap. Begin trapping in early spring to trap as many queens as possible. Keep yellow jackets away from students by placing traps away from where they play. For a more detailed look at IPM for yellow jackets, refer to the Pest Note on the UC IPM website. Rats can cause considerable damage in schools. They contaminate food and damage containers and packaging materials where food is stored. They can gnaw on electrical wires and wooden materials such as doors and ledges and tear up insulation in walls and ceilings. The Norway rat and the roof rat are the two most commonly found rats causing trouble in schools. The Norway rat is stocky and builds burrows along building foundations or in woodpiles. Indoors they tend to remain in basements or on the ground floor. Roof rats are smaller than Norway rats and are agile climbers. They usually live and nest above ground in trees, shrubs or vegetation. As they are found in attics, walls, false ceilings and cabinets. You don't have to see a rat to determine if you have an infestation. Rats are active throughout the year, mostly at night. Look for half-inch to three-quarter-inch droppings and gnaw food or wood materials. Reduce hiding places by keeping garbage and garden debris in receptacles with tight-fitting lids. Then or remove dense vegetation near buildings that provide shelter and travel bridges. Seal all cracks in building foundations and make sure there are no gaps larger than a quarter-inch under doors and in windows. When you have a rat problem trapping is the safest control method. Snap traps work best. For Norway rats place traps close to walls, behind objects in dark corners and where rat droppings have been found. For roof rats place traps on ledges, shelves, branches, fences, pipes or overhead beams. There are pesticide baits available. Do not use baits indoors because dead rats create bad odors. Seal buildings before baiting outdoors to prevent poisoned rats from coming indoors to die. Place baits in tamper-proof bait stations and keep them away from children. Rats can be poisonous to people, pets and wildlife. For more information on IPM for rats refer to the Rats Pest Note on the UC IPM website. Approach weed problems in the schoolyard preventively. Wherever possible eliminate bare ground where weeds can become problems. Use mulches in landscapes and plant competitive plants. Install concrete mowing strips in turf along fence lines and building foundations. Keep turf vigorous with proper watering, fertilization and mowing. When weeds get out of hand and must be controlled use non-chemical methods such as hand pulling where possible, flamers, hot water treatments and string trimmers. Look at what underlying conditions may be causing the problem. Too much or too little water, over fertilizing, compacted soil or poor mowing practices. There any problems such as leaky sprinklers and follow proper maintenance practices. Use herbicides only as a last resort and use selective materials. Use only the amount needed. Timing is important. Control weeds before they seed. For more thorough information on weed ID and management refer to the UC IPM website and check out the weed photo galleries and pest notes on weeds in lawns and weeds in landscapes.