One common misconception is that only certain spiders have venom glands. In reality, all spiders do; however, the potency of the venom, how it works and what reactions can be seen all differ depending on the species of spider and even the object into which the venom is injected. It is important to remember that the venom released by spiders is intended for the immobilization of their prey. A vast majority of the time that prey is another arthropod or insect and therefore somewhat small in size. While there are species of spider that are cause for medical concern in association with their bite, although in Colorado, these instances are rare. There are other contributing factors than just the spider itself as well. The age and/or general health condition of the person that was bit as well as the individual body’s immune reaction to the bite can all play a part in how the bite will affect them. Much in the same way that only certain people experience a serious reaction to a stinging insect or wasp sting, certain people have mild or no reaction to spider bites whereas other people can experience moderate to severe complications.
The two most common spiders our customers call about with great concern are black widows and brown recluse. Western black widows are native to Colorado and are common, whereas brown recluse are not native and are extremely uncommon in the state. In the rare cases in which brown recluse are found within the state it is most commonly determined that they were shipped in from out of state during shipping or moving of items from regions that the spider is native. The cooler climate that is experienced in Colorado during the winter results in brown recluse being unable to become an established species. There are however several species of native spiders that are commonly mistaken for brown recluse. Most commonly funnel web spiders and certain wolf spiders are mistakenly assumed to be a brown recluse, although certain grass spiders may also be confused as well. Brown recluse have identifying characteristics that can be utilized to distinguish them from other species. They are a pale brown in color with long, dark brown legs. A violin or fiddle shaped marking extends from behind the head and the abdomen is solid colored. The other identifying characteristic is one that not many people are willing to or capable of determining at home. Brown Recluses have 3 pairs of eyes (6 total) instead of the typical 4 pairs (8 total). Western widows on the other hand are more easily recognized with their bulb shaped abdomen and “hourglass” marking on their abdomen. Many people do not however realize that while the female is black or dark brown in color, the male may have shades of red, orange and/or yellow body patterns with light brown or gray bands around their abdomen.
When a suspected spider bite occurs, save the specimen if possible in the event that complications arise. Brown recluse bites are a common misdiagnosis in Colorado. Thoroughly wash the area of the suspected bite with an antiseptic solution. Apply ice to the site to reduce swelling and/or pain. If a black widow or brown recluse spider bite is suspected, or in the event that serious symptoms develop it is recommended that you contact your physician. Antivenins are only available for use in patients where a positive identification can be made and not assumed. There are many other medical conditions that mimic the conditions seen by a spider bite, which can make accurate diagnosis difficult.