Around 3,000 spider species have been described in North America, which is ten percent of all described spider species worldwide. Most spiders produce venom, but many spiders are unable to bite due to having fangs that are too short to pierce human skin. The group of spiders known widely as “daddy long legs,” or “cellar spiders,” are easy to recognize on account of their long thin legs and pea-sized body. For decades, rumors have been circulating claiming that daddy long legs spiders produce one of the strongest spider venoms known to mankind, only their fangs are too short to deliver potent venom into the human bloodstream. This rumor eventually gave way to another rumor claiming the opposite. It is now widely believed that there is no truth to the original rumor claiming that daddy long legs are highly venomous. However, recent research has shown that one cellar spider species, Holocnemus pluchei, may produce harmful venom after all.
The H. pluchei species looks like the typical daddy long legs spider, and it is often found around homes and in basements or cellars. Most documented sightings of this species occur indoors, but they maintain a presence on the exterior walls of homes as well. Researchers have found that H. pluchei venom contains hemocyanin and arginine kinase, which are two potent allergens that are harmful to humans. While H. pluchei is unable to bite humans, and therefore, cannot transmit these allergens into the human bloodstream, numerous other arthropods, like cockroaches, flies and mites, spread these allergens within the homes that they inhabit. However, H. pluchei may spread allergens within a home just like the above named groups of insects. For example, another spider that is often referred to as a “daddy long legs” is the huntsman spider, and these spiders are significantly larger than cellar spiders, but they resemble cellar spiders due to their long legs. One case report described a 55 year-old man who sustained an allergic rash on both of his arms after letting a huntsman spider crawl on his two arms for a period of 30 minutes. After reporting to a hospital to present his rash to doctors, the man experienced a severely low heart rate and hypotension. This man’s urticarial rash was certainly due to being exposed to spider allergens, and he required adrenaline therapy and potent histamine antagonists in order to treat his condition.
Have you ever developed an allergic reaction due to being exposed to a spider or insect?