Furrow Orb Weaver: How to Identify and Aid this Valuable Spider

The Furrow orb weaver might be scary, even if you do not have arachnophobia. It does look mean and dangerous, but it is neither. As more and more mosquito-borne diseases spread into the human population, the Furrow orb weaver could become an important asset. Having a few around the exterior of your home may even be your last line of defense.

As a result of the importance of the Furrow orb spider and its harmlessness to humans and most pets, I urge you to leave them alone. Indeed, I certainly will not explain how to kill or remove them.

Furrow orb weaver spider: Description.

There are three species of furrow orb weaver spider in the United States. Larinioides corntus (Furrow orb weaver), Larinioides patagiatus (Dusty orb weaver), and Larinioides sericatus (Gray cross spider).

Furrow orb weaver spiders come with gray, red, olive, gray, or tan abdomens with inky, edged zigzag markings running down their lengths. These markings resemble a furrow or edges of a wavy leaf. The front two legs are longer than the rear legs, but all the legs are banded and have small spines on them.

Furrow web spiders can grow to have a body length of about 1/2 inch, not including the leg span.

Furrow orb weavers have exoskeletons that are dark brown, gray, or reddish and overspread with extremely fine hairs. Unlike other orb weavers, their abdomens are not dull looking but smooth and polished.

Unlike most other spiders, furrow orb weaver males are nearly the same size as females and have the same markings. As a result, furrow orb weavers can survive most winters and are often seen waiting in the middle of their webs.

Gray cross spiders.

Larinioides sericatus, the gray cross spider, looks similar to the furrow orb weaver. Still, it also has a dark ring circling the metatarsus of its rear legs and is darker than the furrow orb weaver’s, with a white-edged exoskeleton and longer legs.

Dusty orb weaver spiders.

Larinioides patagiatus, the Dusty orb weaver spider’s abdomen pattern varies in shape, but the markings are much sharper and more jagged than the furrow orb weaver’s.

Furrow web spider: Habitat.

Furrow orb spiders are found in much of North America, including middle Canada and most of Mexico, Ireland, the U.K., and much of Western Europe.

Furrow orb weavers prefer low vegetation near lakes, ponds, and other moist areas. They build their webs parallel to a surface but several inches above it. Around homes, they build webs anywhere near a night light source, such as a window or porch and garage lights. External nightlights draw plenty of prey to these webs.

Furrow orb weavers are common in lowlands, in low vegetation near ponds and lakes, and in other moist areas. They often build their webs on or under bridges, below the eaves of homes, under porches, and near porchlights that attract the flying insects they eat. Most people see furrow orb weavers near their homes. The webs are often parallel to a wall or window, built within a few inches of the surface.

The furrow orb weaver’s web consists of spiral circles more widely spaced than other orb weaver spiders.

Furrow orb weaver: Diet.

Furrow orb weaver spiders live on flying insects such as moths, mosquitoes, flies, and gnats that get entrapped in their webs.

Are furrow orb weaver spiders dangerous?

No. First, the furrow orb weaver is particularly resistant to biting humans. They will drop off their webs to escape or return to their retreats to avoid human contact.

If you are bitten, aside from a bee sting-like pain and some swelling, the venom and bite are not medically significant to non-allergic people.

Furrow orb weaver spider: Mating.

Males furrow orb weaver spiders must be almost as careful as others make spiders when attempting to mate. The only thing in favor of the male orb weaver is his size, which is nearly as large as the female spider.

After detecting the pheromones of an available furrow orb weaver, the male finds her web and taps and plucks at it to get her attention. If she accepts him, he will soak his palps in his spree and insert them in the female furrow orb weavers’ reproductive opening in her abdomen.

The female furrow orb weaver will then place the eggs in an egg sac attached to vegetation near her web and await their spiderling’s emergence in 3-4 weeks.

Furrow orb weavers can survive through the winter and have a two-year lifespan.

Furrow orb weaver spider: Predators and avoidance of them.

The furrow orb weaver’s biggest threat is birds, but it can also be preyed upon by other spiders and wasps. To avoid these predators, the furrow orb weaver uses a “huddle” strategy during the day.

Here is an article describing this strategy and an extract from it,

“Ecologically, spiders are both predators and prey. Therefore, they must balance being aggressive enough to forage successfully but not so aggressively that they become overly exposed to predation.

Some species of spiders actively forage during clearly defined periods of the day, leading to the hypothesis that they should be less aggressive (or more defensive) during periods when they are not foraging, predicting that antipredator behaviour should be more pronounced during inactive foraging times.

We tested the antipredator ‘huddle response’ in a nocturnal foraging orb-weaver, Larinioides cornutus, and found that, as predicted, the spiders huddled longer in the day than at night.

We then conducted tests to determine whether the cycling of the response was regulated by an internal clock (circadian), and we found that huddle duration continued to cycle under constant dark (with periodicity significantly less than 24 h) as well as under constant light (periodicity nonsignificantly longer than 24 h).

This work adds a novel behaviour to the list of behaviours under circadian control and also to the surprisingly short list of studies demonstrating circadian rhythm in spiders.”