Just like insects, centipedes, millipedes, and crustaceans, arachnids belong to the phylum Arthropoda, which is the largest phylum in the animal kingdom. The most well known arachnid groups include spiders, scorpions, ticks, mites, opiliones, harvestman, and solifuges, the last of which is made up of numerous species that are commonly known as wind scorpions, sun spiders, and camel spiders. More than 45,000 spider species have been documented worldwide, which makes spiders the largest order of arachnids, and the seventh largest order of organisms on the planet. The vast majority of documented spider species produce venom, though only a small minority of spider species possess fangs large and durable enough to penetrate human skin.

While all spider species produce silk, not all spider species use their silk to construct webs for catching insect prey. Some spiders capture prey by using their silk to build snares, while other species use their silk to build handy draglines, protected shelters, and/or nurseries for transporting offspring. Amazingly, the spiderlings of many species use their silk to create kite-like structures that enable them to disperse to faraway areas by riding wind currents, a process known as “ballooning.” The most commonly encountered indoor spiders like cellar spiders and house spiders are notorious for their habit of building numerous cobwebs that often become a nuisance within homes and buildings.

While many entomologists and pest control professionals frequently tell residents that spiders are beneficial within and around homes due to their habit of preying on insect pests, many people cannot tolerate the thought of sharing their home with spiders, especially large and scary looking species. However, Louisiana is home to multiple spider species that public health professionals consider to be medical hazards that require urgent pest control attention when encountered indoors. Several large and hairy spider species frequently appear within Louisiana homes including Carolina wolf spiders, dark fishing spiders, and Parson spiders, but they are not considered medically significant. The four spider species that pose a genuine medical threat to residents within Louisiana homes include southern black widows (Latrodectus mactans), northern black widows (L. variolus), brown recluse spiders (Loxosceles reclusa), and non-native Mediterrranean recluse spiders (L. rufescens). Other potentially dangerous spider species in the state include brown widow spiders (L. geometricus), and possibly, yellow sac spiders (Cheiracanthium inclusum and Cheiracanthium mildei).

Have you ever sustained a spider bite in your home?