"What are fall webworms?
Fall webworms are a native moth that occurs through all of North America, and now the world, thanks to their accidental introduction to Europe during World War II. The noticeable stage of this ugly pest usually appears from June through August, but if a second generation is produced, can extend into October.

Infestations tend to be episodic in nature with back to back bad webworm years occurring about once a decade. However, some webworms will be seen almost every season.

Are there different types?
Two races of fall webworm are described: the two-generation-a-year, black-headed version and the single-generation-a-year, orange-headed form. Both races occur in the South, but the orange-headed form is perhaps a bit more common. The moth usually lays her eggs around mid-June, and about 60-70 days are required to go from egg to pupal stage. The black-headed form begins about four weeks earlier and is able to squeeze in a second generation." https://www.uaex.uada.edu/farm-ranch/pest-management/insect/fall-webworms.aspx

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My sightings have been just stray individuals on annuals which they do not eat: not part of any tree infestation.