Sun Scorpions: Camel Spiders
Not long ago the internet virtually buzzed with stories of the rampaging "camel spiders" that are terrorizing our soldiers in the Middle East. The story went something like this - the camel spiders are 3 feet long and can run 25 miles per hour. They scream like terrified children. They are called camel spiders because they eat camels beginning with the stomach, and they are known to feed on soldiers as they sleep in their sleeping bags. An accompanying photo seemed to verify the incredible size of these beasts, and our offices and university entomology departments got numerous calls and emails from frantic people asking for more information.
There were some versions of the story that claimed the monsters injected an anesthetic when they began to feed, so that you could not even detect that you were being eaten at night, waking up with parts of arms or legs missing. It was also claimed they would instantly run for the shade of your shadow, making for even more risk to your life and health. It is safe to say that about the only truth in this whole scenario is that "camel spiders" do occur in the Middle East. The rest is urban legend, but no doubt a Hollywood movie is already in the works.
Here's the truth.
"Camel Spider" is just a name used in Europe for a wonderful and beneficial bug that we fondly call a sun spider, sun scorpion, wind scorpion, or most correctly SOLPUGID. This arthropod is related to the familiar scorpions, but Solpugids are unable to sting. They do, however, have enormous and powerful jaws and some species are capable of biting, but they inject no venom of any kind, and should be welcomed and enjoyed if they are found in your yard. For those of you lucky enough to have seen the photo on the internet, of soldiers holding what clearly appear to be the 3-foot long monsters, a more careful look shows that the two camel spiders are being held very close to the camera with a pair of pliers, giving the illusion that they are far larger than they truly are. The species in the Middle East can get up to 5 inches long if their legs are stretched out in front and back.
There are around 120 different species of Solpugids in North America, most of these found in the more arid regions such as the Southwest. However, it is very common for homeowners in most other states occasionally to see one of them running across their floors or walls inside the home, and this can be very frightening. The largest kinds in the United States may reach about 3 inches in length, again with the legs stretched out to account for this size. More commonly they may be just over one inch long.
The Features of the Solpugid
If you can muster up your courage and take a close look at a solpugid you will notice some interesting features. These critters are Arachnids, and related to spiders, with four pairs of legs. However, if you count it will look like they have a total of 10 legs, with two especially long and stout legs sticking out in front. These are, in fact, the equivalent of the claws of our regular scorpions, and they are modified appendages of their mouthparts called "palps". The solpugid uses its palps in much the same way insects use their antennae, as feelers to sense what's going on in front of them. The tip of this appendage also has a sticky quality to it that enables the solpugid to more easily capture the small insects that it eats.
The jaws of the sun scorpion consist of an upper pair and a lower pair, and these powerful mandibles can quickly dispatch the prey it captures and then crush the other arthropod to expose the softer insides, which the solpugid then is able to ingest. The jaws also have ridges along their inside edges, and by rubbing these together some species are able to make a squeaking sound similar to that of a cricket. This is far from the "screaming" reported for the Middle East camel spiders, but is a more accurate depiction of what they actually can do. As they run around the solpugid tends to hold its palps and its front pair of legs over its head to keep them out of the way, making them look that much more like an oddity.
Right in the middle of the top of their head is a little cluster of eyes, and as aggressive hunters the solpugids are able to see fairly well from a few inches away. Another set of unusual features on these arachnids is some strange looking protuberances on the underside of their hind legs. These are called "racket organs", the origin of which I have not read, but perhaps they reminded someone of the shape of a tennis racket. Their function for the solpugid is not completely understood, but it appears that they do serve some sensory role.
Female solpugids are a model of motherhood, but do not make particularly good spouses. It is very common for the female, once mating is completed, to grab the male and eat him if he is not fast enough in making his escape from the scene. The male does everything he can to ensure things go well, including a courtship ritual that includes gentle touching and even carrying the female around to put her into a sort of lethargy, but sometimes it just doesn't work out the way he would like. However, following this possible violence the female becomes a devoted Mom, placing her eggs carefully in a cavity in the soil, watching over them until they hatch to baby solpugids, and then capturing food that she brings back and feeds to her young.
What About Controlling Them?
If the solpugids you see are outside the best thing you can do, for both the solpugid and yourself, is to leave it alone and enjoy that fact that you have this aggressive insect-eater in your yard. They really aren't going to harm you, but do a great benefit with their feeding activities. If you still feel the need to discourage them you can eliminate their hiding places and this will encourage them to reside somewhere else, perhaps in your neighbor's yard. Since solpugids are nocturnal - active mostly at night - they need to hide all day under materials on the ground or within debris such as yard trimmings, piles of lumber, firewood, etc. Even if you do not want to completely eliminate these materials you can at least move them away from the house to reduce the opportunity for the bugs to get inside.
Since no one has ever been overwhelmed with large numbers of solpugids in their home, but instead will see just the occasional one, the best control inside will be a vacuum cleaner. Or, of course, just encouraging the poor lost critter to enter a jar and depositing it back outside. Pesticide applications may not be called for to eliminate a single bug. You can then help to "bug-proof" your house by carefully inspecting the exterior and all doors and windows to note where there are gaps that permit bugs to crawl through. These may also be large enough to admit rodents or bats, so closing them off permanently serves several benefits to you. Gaps under doors are particularly conducive to admitting crawling bugs, and there are brush strips that can be permanently installed to eliminate this opportunity.
Holes in outside walls that allow cables, wires, conduits, or other items to be placed into crawl spaces or wall voids should be sealed off. This often will be holes punched through for plumbing, and sometimes the builders are not too careful about the dimensions of that hole, leaving large gaps around the pipes that then lead directly into the kitchen or other rooms. These can be sealed with aerosolized foams, caulking, or other building materials.
Also, of course, if you don't offer the solpugids any foods they won't hang around, so eliminating insects and other bugs will reduce this resource for the predators. Consider contacting a licensed pest management professional to discuss your goals for maintaining a pest free home.