Daddy Longlegs and Cellar Spiders

We’ve all seen them – spiders with tiny, little bodies and long, delicate legs. What you may not know is that daddy longlegs aren’t actually spiders. And what many of us call daddy longlegs are actually cellar spiders. Or crane flies.

Cellar spider (Olei) CC BY-SA 3.0.jpg

Before we get into the differences and similarities, we need to put aside a common misconception. Urban myth states that daddy longlegs have the most potent venom of any spider and that the only reason they aren’t a danger to us is because their fangs are too small to bite us. False on both counts. Daddy longlegs can bite you and their bites won’t hurt you. Their venom is relatively weak.

To figure out which insect you have, you should first ask yourself if it has wings.

Crane fly (Judy Gallagher) CC BY 2.0

Crane flies

If you see a daddy longlegs with wings, it’s a crane fly. Crane flies are the recipient of a different urban myth. As children, we called them mosquito-eaters because we thought they ate mosquitoes. We were wrong. Crane fly larvae feed on the crowns, leaves, and roots of your lawn and other members of the grass family (Poaceae or Gramineae). This includes barley, corn, lemongrass, millet, oats, rye, sorghum, and wheat. Crane flies are pests. If there are no wings present, it’s a spider.

Cellar spiders

The long-legged spiders most of us see are cellar spiders. These spiders have oval- or peanut-shaped bodies and extremely long, delicate legs. If you are willing to get close enough to see [and I urge you to, these creatures are amazing up close!] they may have 6 or 8 eyes, arranged in groups of 3 or 4, respectively. Cellar spiders may be gray, tan, or brown and they often have chevron markings. These spiders hang upside down from their webs and will shake them when they feel threatened.

Marbled cellar spider carrying prey (ערן פינקל) CC BY-SA 3.0

Cellar spiders build messy, irregularly-shaped webs, which are often found in caves, under loose bark, and in the upper corners of many living rooms, garages, and attics. These webs are not sticky, just confusing. Prey become entangled, are bitten, and then thoroughly wrapped up to be eaten later. After being consumed, prey are removed from the web and their empty husks are dropped to the ground.

Rather than feeding exclusively on flies and gnats, cellar spiders prefer eating other spiders. They will often shake the webs of neighboring spiders to trick them into thinking a tasty snack has been trapped. Instead, a fatal bite turns the host spider into the next meal. Funnel weaver spiders, hobo spiders, huntsmen, house spiders, and redback spiders are all favorites of the cellar spider. [Redbacks are related to black widow spiders.] This makes cellar spiders helpful in the house and the garden, reducing the number of potentially dangerous spiders. In a classic win-win situation, cellar spiders are “synanthropic”, meaning they benefit from living near us, too.
 
Members of the Pholcidae family, these arachnids go by several different names: carpenter spider, long daddy, marbled cellar spider, skull spider, vibrating spider, granddaddy longlegs, and daddy longlegs, hence the confusion.

Daddy longlegs

Daddy longlegs have fatter bodies than cellar spiders, and they have a brown stripe on their belly. There are 6,000 to 10,000 species of daddy longlegs worldwide and they’ve been around for 400-million years, with very few changes. This group belongs to the Opiliones order. While Opiliones are arachnids, they are not spiders. The Arachnida class includes harvestmen, mites, scorpions, Solifugae (camel spiders), spiders, ticks, and may include horseshoe crabs. Scientists are still sorting that out.

Harvestmen or daddy longlegs spider (Mehran Moghtadai) CC BY-SA 3.0

True daddy longlegs are harvestmen, not spiders. They are most closely related to mites. If you were to compare cellar spiders with daddy longlegs, you would see that daddy longlegs have single eyes (or no eyes, depending on the species) and fused, pill-shaped bodies. They also differ in that they do not build webs, do not produce venom, and can eat chunks of food, as well as liquids. They defend themselves using stinky chemicals.

These creatures prefer hiding in moist areas, under logs and rocks, so you may find one under your kitchen sink or in a crawl space or basement.

Daddy longlegs are fascinating. They breathe using tracheae in their legs. And if one of those legs breaks off, as they too often do, it will continue to move because of a pacemaker mechanism found in each femur. This movement may continue for up to an hour. Scientists think this may have evolved to trick predators.

While daddy longlegs are predators in their own right, they get most of their nutrients from decomposing plant and animal matter, and manure. When they do hunt, they ambush their prey. This is impressive because their eyes cannot form images. [Don’t ask me. I have no idea how they do it.]

Daddy longlegs daddies are territorial and often care for the eggs laid by several different females, cleaning the eggs and protecting them from unrelated, egg-eating female daddy longlegs. [And we think our families are complicated!]

So, crane flies are pests, cellar spiders are helpful, and true daddy longlegs are pretty much neutral. Now you know.