Local health officials are warning residents to wear bug spray and be mindful of outdoor nighttime activities after mosquitoes trapped in town tested positive for West Nile virus. The findings came after state health officials said two people, a Norfolk County man in his 30s and a Plymouth County man in his 70s, had contracted the mosquito-borne illness last month. Several area communities, including Concord, Lexington, Needham, and Waltham, have been raised to a moderate risk level for West Nile, meaning human infection is either likely or has already occurred. Residents can avoid mosquito bites while outdoors by wearing insect repellent and donning long sleeves from dusk to dawn. Since mosquitoes lay eggs in standing water, officials also advise residents to drain any outside their home, including in gutters, drains, or 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 secure. For more information, visit the Health Department’s page on the town website, www.wellesleyma.gov.