Pholcid Spider with Eggs

I found this female Pholcus spider with her eggs, in a corner of my kitchen. Here I have used Canon EOS 70D with Canon EF 100mm f/2.8L Macro IS USM using 36mm Kenko extension tube. This whole setup is illuminated by Godox Ving V860C Flash fitted with LumiQuest Softbox III diffuser.

I was holding the flash in my left hand and camera on the right and used wireless trigger to activate the flash. The drawback of this method is that there is a faint shadow on one side. Since both your hand are occupied it is difficult to manage the setup if your subject is moving around. The spider was in such a tight corner, I had no scope to setup flash on a support. Female after she lays her eggs, she wraps them in silk strands and carries the package in her chelicera (jaws), as seen in these pictures.

Pholcus spider is found throughout the world. It is a commonly called cellar spider or daddy long legs. Confusion often arises over its name “daddy long-legs” because the same term is also applied to two other distantly related arthropods: firstly another arachnid from order Opiliones otherwise known as the harvestman, and an insect less ambiguously called the crane fly.

Pholcus spider can be found in undisturbed, low light locations. Some places one might encounter this spider are in basements, under stones, under ledges, and in caves. People most often associate these spiders with living on ceilings and in corners in homes. They make their webs large, loose, and flat, but they can make them in irregular shapes to fit into surrounding objects. Their webs are normally oriented horizontally. Pholcus spider hangs upside down on the web it makes.

Pholcus spider is pale yellow-brown except for a large gray patch in the center of the cephalothorax. The body and legs are almost translucent. These spiders are covered with fine gray hairs. The head is a darker color around the eyes. A translucent line marks the dorsal vessel. There are eight eyes: two small eyes in front of the two triads of larger eyes.

Females are seven to eight millimeters in length and males are six millimeters. An urban legend states that Pholcidae are the most venomous spiders in the world but that it is nevertheless harmless to humans because its fangs cannot penetrate human skin. Both of these claims have been proven untrue. Recent research has shown that pholcid venom has a relatively weak effect on insects. In the MythBusters episode “Daddy Long-Legs” it was shown that the spider’s fangs (0.25 mm) could penetrate human skin (0.1 mm), but that only a very mild burning feeling was felt for a few seconds.

In studies done by Gabriele Uhl at the University of Bonn, male Pholcus spider seemed to be attracted to and to mate with larger females more often than smaller females. This may increase reproductive success for males, because large females produce more eggs than smaller females.

Before mating, a male spider deposits some sperm onto a little web, and then sucks it into a special cavity within his pedipalp. During mating, which can take several hours, the male deposits his sperm into the female’s epigynum, which is an opening on the underside of her abdomen. Females can store the sperm in a special cavity at the beginning of the uterus, called the uterus externus, until it is time for her eggs to be fertilized.

Timing of fertilization and laying depends on the availability of food. Because the sperm are stored for some period of time, it is possible for a female to mate again. If this occurs, the sperm from the two males mixes in the uterus externa. However, the sperm of the last male mated with has priority in fertilizing the eggs. This is because of a mechanism of sperm removal during mating. Males perform rhythmic movements during copulation, which results in extrusion of most of the sperm already in the uterus externa.

After a female lays her eggs, she wraps them in silk strands and carries the package in her chelicera (jaws), located on the underside of her body as seen in these pictures. The only parental care female Pholcus spider offer their young is nine days of protection as the prenymphs finish developing into spiders. The young spiders then leave the maternal web, and go look for a place to build their own webs. Pholcus spider can live up to about three years.

When Pholcus spider is not mating, it is a solitary creature that work on catching food in its web. Pholcus spider seems to prefer other spiders and small insects as prey. Also, males and females have both been known to engage in cannibalism. Females have been seen invading another spider’s web, eating that spider, and using the foreign web to catch new prey for themselves. These spiders kill and digest their prey using venom.

When the web of Pholcus spider is disturbed, the spider swings its body around rapidly with its legs attached firmly to its web. It swings fast enough that the spider becomes very hard to see. This may be a form of camouflage.

Because their diet is primarily insects, these spiders play the important role of controlling the growth of insect populations.