Hi Mara,

Yes, swallows do harbor "swallow bugs", but they rarely are a threat to humans. Swallow bugs will stay in the nest to feed on their host, the birds. Once the swallows migrate and leave the nest, it's possible the swallow bugs could wander into the home if there are entry points. 

Barn swallows tend to be solitary nesters compared to cliff swallows that nest in large colonies. The bug and mite population is likely much higher in cliff swallows due to the higher population of hosts.  

If the neighbor chooses to leave the swallow nests on her porch, as prevention, she could seal up cracks and crevices around the area to prevent any swallow bugs from wandering indoors. You could also do the same if you are concerned about swallow bugs wandering to your home. 

Swallows are federally and state protected under the Migratory Bird Treaty Act of 1918 meaning that active swallow nests (nests in use with eggs or babies) can't be not removed. Once the swallows have migrated, nests can be removed. If she would like to deter them from building a new nest, she could add barriers in the nesting space. More info here. 

Barn swallows are beneficial in providing pest control. They feed on nuisance insects such as mosquitos. 

Hope this helps! Let me know if you have any other questions.

Thanks,

Lisa

Lisa Mason
Horticulture Specialist, Entomologist
Colorado State University Extension, Arapahoe County