State health officials are advising residents to cover up and use bug spray after they found a mosquito infected with the West Nile virus in town last week. Other Middlesex County communities with mosquitoes carrying the virus this summer include Belmont, Waltham, and Watertown, according to the state. Residents can avoid mosquito bites by using insect repellent and wearing long sleeves and pants when outside from dusk to dawn. Since mosquitoes lay eggs in standing water, officials also advise residents to drain puddles from collection areas, such as gutters, unused flowerpots, and wading pools. Residents can also keep mosquitoes out of their home by making sure all screens in their doors and window are tight-fitting. For more information, visit the state health department’s website, www.mass.gov/dph.