The increasing presence of Joro spiders has sparked curiosity about their natural enemies. This article explores the known predators that help manage their populations.
Introducing the Joro Spider
The Joro spider ( Trichonephila clavata ) is an orb-weaver species recognized by its distinctive appearance. Female Joro spiders are striking, with vibrant yellow, blue-black, and red markings, and a leg span up to four inches. Males are considerably smaller, typically around 0.3 inches, and less vibrantly colored.
These spiders construct large, intricate, golden-hued orb webs that can span up to ten feet wide. Joro spiders are generally docile and non-aggressive, preferring to retreat when disturbed rather than bite. Originating from East Asia (China, Japan, Korea), the Joro spider arrived in the United States around 2013, likely via shipping, and has since established itself in various southeastern states.
Avian Predators
Birds are significant predators of Joro spiders. Various bird species have been observed preying on these arachnids, demonstrating their role in controlling spider populations. Birds may pluck Joro spiders directly from their large webs or consume them if found on the ground.
The Joro spider’s size, while large for a spider, still makes it a suitable meal for many common songbirds. Some birds will even sit on the Joro spider’s strong web to steal captured insect prey. This interaction highlights how birds opportunistically feed on Joro spiders, integrating them into their diverse diets. They are considered easy prey, especially when they are smaller in their early life stages.
Insect and Arachnid Predators
Joro spiders are also preyed upon by various insect and arachnid species. Mud dauber wasps are notable predators, known to capture spiders to provision their nests for their larvae.
Other larger spider species also pose a threat to Joro spiders. These arachnids may engage in predatory behavior, especially when competing for territory or resources. While Joro spiders are large, they remain vulnerable to certain well-adapted insect and arachnid hunters within the ecosystem.
Other Opportunistic Eaters
Beyond birds and specific insects, other animals may opportunistically feed on Joro spiders. Small reptiles, such as lizards, are known to consume spiders and will likely prey on Joro spiders if encountered. Frogs are another group of amphibians that may capture Joro spiders, using their quick tongues to snatch them from webs or nearby foliage.
Small mammals, including squirrels, have also been noted to eat spiders. While not primary hunters of Joro spiders, these generalist predators will include them in their diet if the opportunity arises. Bats, which are insectivorous, can also consume Joro spiders, potentially catching them in flight. These instances are often less frequent or documented compared to predation by birds and wasps, but they contribute to the overall predatory pressure on Joro spider populations.