This yellowjacket is a major pest species in California. It is primarily a scavenger and in the summer months adults are common around garbage receptacles in picnic and barbeque areas. Nests are usually constructed in abandoned rodent burrows or in house walls and attics. Nests contain 500 to 5,000 workers and start to decline in late September to October.
Nests are usually underground, commonly being found in rodent burrows. Colonies can be large with 5,000 workers at its peak. Adults have a wide range of prey including slugs, spiders, grasshoppers, flies, hemipterans and homopterans. This species is the most common pest yellowjacket in the Western United States. Population explosions of this yellowjacket can occur every few years, usually in conjunction with warm, dry springs.
Adult Activity Period: April – October
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Website Accessibility Policy
Napa County Mosquito Abatement District is fully committed to providing accessible facilities, elements and
channels of communication to all members of the public. As part of this commitment, Napa County Mosquito Abatement District
has a policy of providing an accessible website compatible with the Web Content Accessibility Guidelines (WCAG 2.1) and
commercial screen reading software. All features of the website are coded to allow individuals with vision and
other impairments to understand and use the website to the same degree as someone without disabilities. We welcome
feedback and can often resolve issues in a timely manner if they arise.
If you need any special assistance or accommodations:
Napa County Mosquito Abatement District has designated a compliance officer for website disability-related accommodations.
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In addition to testing with users with a wide range of disabilities and coding our website to WCAG standards,
Napa County Mosquito Abatement District regularly scans its website to ensure ongoing compliance, and makes timely
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