Trapdoor spiders as well as tarantulas belong to a group of spiders called mygalomorphs. These are old world spiders with downward facing fangs. Both are similar in body structure and mistakes in identity are common…. which I can attest to. Most spiders we are familiar with have fangs that are fixed side-to-side. They also inject venom that liquifies the innards of their prey. This essentially allows them to slurp up the insides of their meal like an insect slurpee, leaving behind the skin of the unfortunate victim. Trapdoor spiders, tarantulas and their ilk also inject venom to subdue their prey, then proceed to consume their entire meal, skin and all!
With over 50 species, trapdoor spiders in the genus Ummidia are widespread throughout the Eastern and Southern United States. Several species occur throughout Missouri but are rarely found by humans except under the right conditions. Typically, after a heavy summer rain males and females will be forced out of their burrows. Or in times of severe drought, they will leave the confines of the burrow in search of water. They are often encountered at this time in pet water dishes or swimming pool skimmers. Males will wander in July and August seeking mates and may be encountered by us during one of these jaunts. It can be a bit concerning to be faced with a large spider that possesses giant fangs. Surely it must be dangerous, right? These spiders are in fact harmless to humans. The venom they possess is only harmful if you are an insect or other small prey item they typically eat. Otherwise, the venom is no more dangerous than bee venom, however the bite will be painful…after all they have large fangs. Thankfully they are docile by nature and not confrontational. They prefer to scurry away rather than stand their ground. If harassed, they may rear up and show their fangs. This is a pretty good deterrent for us humans, especially those who have a case of arachnophobia. I was able to coax this one onto my hand and it just sat their calm as can be and never once acted threatened or offered to bite.
Like many animals in nature, the predator becomes the prey, and this spider is no exception. There are several species of spider wasps that are tarantula and trapdoor spider specialists and seek out the burrows these spiders hide in. These spiders have evolved a way to somewhat avoid predation by these determined wasps. When a wasp is sensed at the opening to the burrow the spider will use its fangs to cut a hole in the door to the burrow to hold it closed, then braces its eight legs against the inside of the burrow and holds on for dear life. Because it really is a matter of life and death for the spider. Should the spider not succeed the wasp will sting the spider and paralyze it. The wasp will then lay one or two eggs on the spider. When the eggs hatch the wasp larvae will feed on the spider until they are ready to pupate, and the spider perishes. A gruesome way to leave this world to be sure.
These are truly one of nature’s most unique spiders, calm by nature and posing no threat to humans. Instead, they provide excellent pest control from the secret lairs they carve out for themselves. If you find yourself faced with one of these beautiful spiders, try to humanely escort it back where it belongs.