Another creature often called daddy-longlegs is actually a spider. Danger to humans. The nickname might also refer to a crane fly, which is a true fly and a member of … Pholcus phalangioides is a uniformly grey spider with rectangular, elongate abdomen and is found throughout the U.S. Holocnemus pluchei also has a rectangular, elongate abdomen but has a brown stripe on the ventral side (the belly side - which is typically directed upwards since the spider hangs upside down in its web) which covers its sternum and is a stripe on the abdomen. I was going to just buy some daddy long legs and put them in the attic or storage closets so they can eat all the bugs. They are, in fact, called Harvestmen. Daddy long legs are omnivores and eat a wide variety of things like aphids, caterpillars, beetles, flies, mites, small slugs, snails, earthworms, and other spiders. College of Natural and Agricultural Sciences. HEHEHEHE