What are these? - Ask Extension
We found these in our attic. We wondered what insect they were.
Knowledgebase
What are these? #864728
Asked April 16, 2024, 11:36 AM EDT
We found these in our attic. We wondered what insect they were.
Washington County Oregon
Expert Response
Hi Mark,
Those are mud dauber wasp nests. We have 2 mud dauber species in Oregon: the black-and-yellow mud dauber (Sceliphron caementarium) and the blue mud dauber (Chalybion californicum). Both are native species in our region. Here are what the adults look like...
https://bugguide.net/node/view/668720
https://bugguide.net/node/view/1451931
In contrast to yellow jackets and a few other wasps and bees, mud dauber wasps will only very rarely sting people or pets, so you do not have to worry about those nests from a safety standpoint. Although mud daubers look pretty fierce, they are not aggressive and will sting only if they are held or trapped next to the body. Their sting is also mild and much less painful than that of social wasps (e.g., yellow jackets, baldfaced hornet, European paper wasp) or social bees (e.g., honey bee, bumble bees).
Mud daubers are solitary wasps that build nests consisting of up to 25 cells made of mud. Nests are built in sheltered locations, sometime even in or on buildings occupied by people. The adult wasps can often be found on flowers during the growing season. In addition, the adult females hunt spiders and paralyze and capture them. The spiders are stuffed into the wasp’s nest cells to provide food for the developing larvae.
Mud dauber adults all die in the fall and early winter, so it is the immature stages (larvae and pupae) that overwinter in a nest. Later in spring or early summer the new adults will emerge. The nests you have with open cells appear to be old nests that adults emerged from before, but the nest in the middle appears to have closed cells that could be housing larvae or pupae. You can take any of the nests with open cell off and dispose of them without any risk of harm to developing wasps. If you want to allow the wasps in the middle nest to continue to develop, you could pry the nest off as gently as possible and put it in a protected place outdoors where the nest won't get rained on.
Hope that helps!
Those are mud dauber wasp nests. We have 2 mud dauber species in Oregon: the black-and-yellow mud dauber (Sceliphron caementarium) and the blue mud dauber (Chalybion californicum). Both are native species in our region. Here are what the adults look like...
https://bugguide.net/node/view/668720
https://bugguide.net/node/view/1451931
In contrast to yellow jackets and a few other wasps and bees, mud dauber wasps will only very rarely sting people or pets, so you do not have to worry about those nests from a safety standpoint. Although mud daubers look pretty fierce, they are not aggressive and will sting only if they are held or trapped next to the body. Their sting is also mild and much less painful than that of social wasps (e.g., yellow jackets, baldfaced hornet, European paper wasp) or social bees (e.g., honey bee, bumble bees).
Mud daubers are solitary wasps that build nests consisting of up to 25 cells made of mud. Nests are built in sheltered locations, sometime even in or on buildings occupied by people. The adult wasps can often be found on flowers during the growing season. In addition, the adult females hunt spiders and paralyze and capture them. The spiders are stuffed into the wasp’s nest cells to provide food for the developing larvae.
Mud dauber adults all die in the fall and early winter, so it is the immature stages (larvae and pupae) that overwinter in a nest. Later in spring or early summer the new adults will emerge. The nests you have with open cells appear to be old nests that adults emerged from before, but the nest in the middle appears to have closed cells that could be housing larvae or pupae. You can take any of the nests with open cell off and dispose of them without any risk of harm to developing wasps. If you want to allow the wasps in the middle nest to continue to develop, you could pry the nest off as gently as possible and put it in a protected place outdoors where the nest won't get rained on.
Hope that helps!
