Trying to keep bugs from bombing sticky stuff on cars and sidewalks this summer, Paul Cannefax, hired by the city's Urban Forestry Division, sprays trees with a substance similar to vegetable oil. The city aims to spray every maple and linden tree in town before insects who feed on trees appear. Every year, the city receives complaints from people saying bugs dropped sticky stuff from trees onto their cars. The spraying will take up to six weeks and will cost the city about $25,000, half what the city paid mostly private contractors for last year's job.