Myth #2 – Daddy Longlegs are the most poisonous spiders known, but their fangs are too weak to pierce human skin.
Wrong… Wrong… and WRONG! This commonly repeated, but totally false belief is incorrect on at least three levels:
First, daddy longlegs technically are not spiders. Rather, they are classified into their own taxonomic group – the Opliiones. This is separate from the taxonomic grouping of spiders: the order of Araneae.
Second, daddy longlegs do not produce any venom at all, let alone a highly poisonous toxin.
Third, daddy longlegs entirely lack fangs. Some types of daddy longlegs in Idaho have mouth parts that for an enlarged pincer-like tooth, and so might slightly pinch, but none bite.
This story probably originated because of the physical resemblance of daddy longlegs to cellar spiders. The so-called daddy-longleg spiders Cellar spiders do produce biologically toxic venom, but indeed their jaws are too weak to bite people. A simple way to distinguish living specimens of these two is from their spinning web habits. Daddy longlegs do not spin webs and are seen running agilely over the ground. In contrast, Cellar spiders do spin webs – where they are almost exclusively found. If they are knocked off their web, cellar spiders move clumsily on the ground.