Fall Webworm Moth (Hyphantria cunea) on Sep 27, 2023

Submitter does not have a specimen

Description of specimen

Many nests, looking like a large sack made of spider webs. Inside each sack were thousands of small round brown eggs. Within the sack were a worm or caterpillars that had stripes and "green" blood. No moths had developed yet, that I could tell. We cut out all the sacks and infected leaves which the caterpillars had eaten. All this was taken to the dump. We sprayed the tree with a natural 2 in 1 spray, washed down the driveway and sprayed the driveway as well. Days later, I found 3 more caterpillars and I stepped on them. They squirt out green "blood".
Feel free to call me 541-469-2443 or come by.

I remember perhaps 10 years ago on Hwy 199, (Ca.) a road we at the coast must take to go to Medford, All the trees along that area were covered in a spider web looking nests also.

Commentary

Gypsy moth does not spin webs, this sounds more like fall webworm which is native and commonly crops up on multiple hardwood species this time of year. Take a look at this fact sheet and see if it looks similar: https://www.oregon.gov/odf/Documents/forestbenefits/Webworm_2017.pdf

Fall webworm is only an aesthetic pest and does not typically kill plants, buds are not harmed and the plants will reflush leaves as normal next year. Be advised that spraying general insecticide can also harm beneficial predators and parasitoids that help keep pest numbers low.

Christine Buhl
Sept. 27, 2023, 8:45 a.m.