What is the technical term for "fear of spiderwebs"?

Not fear of spiders. Fear of their webs. Is there a name for this?

Well, the Ancient Greek for spiderweb is αραχνιον (arákhnion). Try “arachniophobia.” That probably wouldn’t be used because of its similarity to the fear-of-spiders word, but that seems to be how they make them: Greek root meaning object-feared + phobia.