Marbled Orb Weaver, Vol. 9, No. 31
Araneus marmoreus
Order: Araneae
Family: Araneidae
“We were out walking in the woods just before Halloween and ran into several big, round-bellied spiders that had their webs strung across the trail. Most were yellow, but our daughter found one that was pumpkin-colored—just perfect for Halloween. What kind of spiders are these, and why are they hanging out in the woods this time of year?”
Marbled orb weaver is the approved common name, but they are sometimes called “Halloween Spiders” or “Pumpkin Spiders.” This last name is most often used for the orange color form, but marbled orb weavers vary in color and markings, ranging from white, to yellow, to orange, with yellow being the most common color in our area. This is one of our more widely distributed spiders. Marbled orb weavers occur throughout the continental US and into Canada, as well as through much of Europe. These big, colorful spiders are hard to miss when you encounter one with its web strung across your trail on a woodland walk.
But why is a big, colorful spider just hanging out in the open like this in the daytime where it is exposed to birds and other predators? Are they so venomous they know nothing is going to bother them? Brightly colored animals are often venomous, or dangerous in other ways, but that is not the case with marbled orb weavers. They can bite if mishandled, but they are slow to do so, and the bite is not seriously venomous. They remain exposed on brisk fall mornings because they are too cold to make it back to their normal daytime retreat.
Marbled orb weavers overwinter as eggs in egg sacs hidden among leaves and twigs. The spiderlings hatch in the spring and become adults by mid-summer, to mate and begin to deposit egg sacs of their own. During these early stages of their life, they remain hidden during the day but are active at night, capturing prey by building their webs across openings to intercept flying insects in wooded areas or along woodland edges.
In late fall, after they have produced all the egg sacs they are going to produce, and especially after temperatures begin to cool, the big female spiders are less careful to seek refuge during the day. Like insects, spiders are cold-blooded and move slower at lower temperatures. In the early evening it is still warm enough for them to build webs across their favorite openings and hunt for prey. But nighttime temperatures can drop sharply during the fall, and sometimes they just can’t move well enough to take refuge early on a crisp fall morning. The adults do not survive through the winter.
Hentz orbweavers, black and yellow garden spiders, and golden silk spiders are three other species of orb weavers that are common in the state, although you may have to go to the southern half of the state to see golden silk spiders.
Last Article of the Year: Like marbled orb weaver spiders, Bug’s Eye View is finished for the year. This is the last article of 2023, but Bug’s Eye View will resume next spring.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
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