Arachnids: Unconventional House Guests


Hot, dry weather can invite some unexpected houseguests into your cool home. Arachnids are one species keen to try out your hospitality.
Striped bark scorpion stalking a cricket at the Fort Worth Nature Center
A striped bark scorpion on the prowl for its next meal. Photo by FWNC&R Staff.

With rising summer temperatures reaching or surpassing 100 degrees, we are not the only life forms seeking a reprieve from the scorching sun. Wildlife must apply different strategies to shed or avoid excess heat, and that may include looking for relief in cool buildings. Our homes become a beckoning oasis, where food, cooler temperatures, and water provide a hospitable alternative to the hot, dry weather outdoors. Some of these unexpected summer guests are flat-bodied scorpions that, instead of hiding outdoors, move into our climate-controlled sanctuaries to avoid overheating and dehydration.

The most widespread scorpion in Texas and North Central Texas is the striped bark scorpion, Centruroides vittatus. These yellow- to tan-colored arachnids, with two broad darker stripes on their abdomens, are sometimes unsolicited summer visitors. Scorpions, overall, are efficient, nocturnal predators that will eat just about anything small enough for them to capture and devour. Our homes may offer a tempting variety of house insects, including roaches, silverfish, and crickets.

Scorpion hunting success depends on its camouflage techniques. Scorpions prefer dark, damp, and quiet places to await a meal or avoid being seen. When weather conditions are favorable, they hide outdoors beneath rocks, vegetation, or logs, where food is more available. Hot summers drive striped bark scorpions indoors to escape the dry heat. Our closets, indoor house plants, or shoes mimic outdoor habitats where scorpions may feel at home as they await their insect meals.

Scorpions’ nocturnal activities serve as a way to manage temperature and desiccation in their arid habitats. Their watertight bodies have a waxy layer of cuticle that helps them reduce water loss. Even though scorpions obtain much of their water from their prey, we may encounter them more often in places like our bathrooms or kitchens that maintain moisture throughout the day. These areas become opportunistic summer watering holes for scorpions. The waxy cuticle not only keeps them from dehydrating but also makes them visible to us under ultraviolet light. Scorpions glow a blue-green color for reasons yet unclear to scientists. The ability to fluoresce may play a role in detecting and avoiding damaging light, helping attract insects, or serving as a means to communicate with one another.

As we seek ways to cool off this summer, it’s no surprise that some wildlife have also discovered that air-conditioned homes with running water and tasty food are favorable to summer survival. Striped bark scorpions are beneficial predators that help rid our homes of unwanted house insects. Knowing more about the reasons for their summer habits allows us to be aware of our unconventional house vacationers.

By Laura Veloz, Naturalist, Fort Worth Nature Center & Refuge

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