Get Wild: Spiders and bats, just in time for Halloween |

Get Wild: Spiders and bats, just in time for Halloween

Frances Hartogh
Get Wild
A shamrock orbweaver spider is pictured Oct. 2 along Eby Creek near Eagle. Its abdomen can be various colors, usually beige or brown, but it can also be orange.
Frances Hartogh/Courtesy photo

During this Halloween week, let’s take a moment to pay tribute to two of our favorite wilderness neighbors: bats and spiders. While their presence might cause concern for some people, often due to misinformation, spiders and bats play crucial roles in the environment.

Spiders are highly beneficial members of the class arachnida that survive by eating insects. They are an important biological tool for controlling pests in gardens, homes, crops and our wilderness. These eight-legged friends of the environment capture prey by using silk and venom.

Are there spiders at high altitude? Yes. In fact, the Himalayan jumping spider, which lives at elevations of up to 22,000 feet in the Himalayas (including Mount Everest), may be the highest permanent resident on Earth.

The web of our local shamrock orbweaver spider, Araneus trifolium, can be up to 2 feet across. The abdomen can be various colors, usually beige or brown, but it can also be orange like the Halloween-themed shamrock orbweaver that visited our outdoor meeting this month near Eagle. Araneus trifolium is sometimes confused with the orange orbweaver species Araneus marmoreus, also called the pumpkin spider. The shamrock spider is distinguishable from other orbweaver species by several white dots on its back.

While there are a few spiders whose bite requires medical attention, these are rare in the High Country. Our cold winters and dry climate make the notorious brown recluse, Loxoceles reclusa, especially rare. The western black widow, Latrodectus hesperus, while more common, rarely bites and is not aggressive. Widows prefer to build their webs near the ground in dark, undisturbed sites, such as abandoned rodent burrows and dusty window wells. Red or red-orange markings on the underside of the abdomen, sometimes in the form of an hourglass or two separate triangles, are characteristic of widow spiders. Their bite is painful and potentially dangerous because it contains a nerve venom. Anyone who suspects they’ve been bitten by a black widow should seek medical treatment.

A black widow spider.
Getty Images

Aligned with Halloween is national bat week! Though often misunderstood, bats, like spiders, play a valuable role in our ecosystem. Of the 18 species found in Colorado, some bats are year-round residents, while others migrate. Bats can be found in every habitat in our state, from the eastern plains to our high-mountain wilderness forests. Bats pollinate plants and crops, and they help to control insect populations: They can eat 1,200 mosquitoes in an hour!

Bat species you’re most likely to see in Summit County are the big brown, the silver-haired and the townsend’s big-eared bat. The big brown bat, Eptesicus fuscus, can have a 16-inch wing span, live 20 years and range up to 40 miles in a single night, but they weigh under an ounce! They roost in caves, mines, tunnels and crevices, and they hibernate from late October to April in locales with low, stable temperatures ranging from 32-53 degrees. Females give birth to one or two pups in springtime.

Bats are the only mammal capable of true and sustained flight. In a process called echolocation, bats locate their insect dinners by emitting high-pitched sounds, up to 20 beeps per second, while listening to the echoes. With forelimbs adapted as wings and long spread-out digits covered with a thin membrane, or patagium, some bats can reach speeds up to 100 mph!

Colorado Parks and Wildlife monitors bat populations as part of a nationwide effort to detect changes from threats like the fungus that causes deadly white nose syndrome. During bat week, visit Parks and Wildlife’s website to learn more about these fascinating mammals and how you can help with bat conservation.

Frances Hartogh

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