Black Widow Spider vs. Eastern Black-necked Garter Snake; near Moffat, Texas 2

— This article by Jerry Cates and Bridget W., first published on 11 August 2010, was last revised on 23 October 2013. © Bugsinthenews Vol. 11:08(07).

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Eastern Black-necked Garter Snake (Thamnophis cyrtopsis ocellatus), juvenile; Bridget W., on Lake Belton, near Moffat, TX

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(1) Spider Extermination and Control

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Meet the snake in this drama. This juvenile eastern black-necked garter snake (Thamnophis cyrtopsis ocellatus), was  hanging out at lake Belton, near the central Texas city of Moffat.

The species is a marine carnivore, eating frogs, toads, minnows, and the like. Rarely, if ever, do snakes in the genus Thamnophis eat insects or spiders. Earlier versions of this article stated that it was crawling around under some rocks, hoping to bump into a juicy spider, but as one commenter pointed out, that was very unlikely.

Evidently it did manage to bump into a juicy spider, but not because it was looking for one. More likely, from all indications, the spider in this drama was only too happy to look on the snake as a source of food, even if the snake had no interest in tasting the spider.

Bridget W. wrote:

Jerry,

Attached is a picture of a (garter) snake, in the web of a black widow spider.

When I first found it, the snake was moving really slowly, stuck in the web.

I saw the swellings on the snake’s body & thought it might have just swallowed something.

Now, looking at the picture closely, I can see that there are actually several places where the snake was bitten by the black widow.

I hadn’t seen the spider yet, though. That wasn’t until later, on the following day.

Now meet the black widow spider:

Western Black Widow (Latrodectus hesperus), female; Bridget W., Lake Belton near Moffat, TX–2010

This is a mature, female, western black widow spider (Latrodectus hesperus), the largest of the five species of black widow spiders native to North America.

It is distinguished from the other North American black widows by the shape of its ventral red hour-glass marking.

In the case of Latrodectus hesperus, this marking–as described by B. J. Kaston in his book “How to Know the Spiders” (3rd ed., 1972) p. 101–consists of two triangles, joined in the form of an hourglass, the anterior triangle being longer and broader than the posterior triangle.

Just as observed with this specimen.

Again, here are Bridget’s words:

I finally saw the spider, just as the sun was going down the next day, and realized it was a black widow.

The next morning I came back out and found that the spider had wrapped up the snake in silk. I left it alone, and did not look at it again that day.

The next day, though, I looked again. The snake’s body had been moved way back under the rocks. It was starting to smell, and I didn’t want the spider around with dogs who go up & down that rock wall.

So I sprayed the spider with a pesticide aerosol, which–incidentally–made the web more visible.

I could see, in fact, that the web continued onto more of the rocks in my back yard, This led me to spray more of the web, just to make sure I killed the spider.

About 4 feet from the original spot, out walks a black widow (I figured there must be a tunnel behind the rocks). Looking back where I sprayed the first one, I saw its lifeless body on the ground. This new one was a second black widow.

Western Black Widow (Latrodectus hesperus), female; Bridget W., Lake Belton near Moffat, TX–2010

Let’s take a closer look at the swollen areas on this snake’s body.

By the way, these photos, like all the photos posted on this website, can be enlarged by placing your cursor over them and clicking.

See the reddish areas where the spider’s fangs penetrated the snake’s skin?

There are at least four such places where both fangs bit the snake, visible in this photo.

Black widow venom contains a powerful neurotoxin that paralyzes the musculature of the bitten animal.

That explains why this snake, which Bridget reported to have been about eight inches long (an estimate that, more than likely, was very conservative; newborns of this species measure 7.5-10 inches long, and this snake was likely several weeks old and perhaps as much as 16-18 inches long, nose to tail), was moving so slowly when she first saw it.

The silk strands making up the black widow’s web are, like those of most orb weavers, remarkably strong.

Some investigators have conducted tests to compare various silk strands produced by spiders of different genre and species, in the expectation that considerable variations would be observed.

Those tests have generally failed to detect significant qualitative differences.

Still, it seems to me black widow silk is especially strong, perhaps because it spans relatively short distances.

I sometimes joke that you can hang meat from a black widow’s web. In fact, that was what this black widow did.

But instead of butchering its catch, the black widow–like most of the true spiders–sucks the juices out of its prey.

To facilitate this, the spider’s venom also contains powerful enzymes that break down proteins, converting much of the prey’s interior structures from a semi-solid to a liquid state.

Western Black Widow Spider feeding on its prey, an Eastern Black-necked Garter Snake; Bridget W., on Lake Belton near Moffat, Texas

Bridget wrote more:

This photo was taken on day 3 when the snake had been dragged way back under the rock, a distance of probably 10-12 inches from where it was first caught in the web, bitten, and wrapped up.

Notice that the spider’s body is about as long as the snake’s head, from neck to nose. The snake’s skin, at this point, appears to have been drained of much of its edible contents.

The predation that constantly takes place in the natural world is boldly illustrated here.

We see that interplay all around us, as birds capture and swallow flying insects and an occasional spider, and as spiders in their orb-webs capture, swathe in silk, and consume large grasshoppers. We’re used to witnessing such scenes.

This example, however, is different, in that a relatively diminutive predator–a spider that was perhaps no more than 3/4ths of an inch long from its fangs to its spinnerets–captured, killed, then consumed a much larger predator–an 8-inch long spider-eating snake.

In truth, such dramas as this probably take place in our yards, sheds, garages, attics, and–yes–often inside our homes, more often than we realize.

Bridget would never have known about the family of black widows in her yard had she not been inquisitive enough to get down on all fours and peer into the gaps under the landscaping rocks in her back yard. And, had she not sprayed the webbing with a pesticide, ultimately killing two large female black widows, that spider family would still be fully intact, with each female producing as many as nine egg sacs containing from 100-400 eggs each, just this year alone.  Of course, some remnants of that spider family are likely still around, and Bridget will be wise to search her back yard diligently for signs of them.

Bridget wielded a pesticide aerosol with excellent effect in this particular situation. Unfortunately, such contact poisons are not very good at ridding the voids under rocks of hidden, unseen spiders. Habitat modification will do what ordinary pesticides cannot.

In addition to the use of soap-and-water solutions, consider using a natural, plant-oil based cleansing spray,  in garages and other well-ventilated spaces, or inside homes for particularly serious cleansing projects that can actually weaken the silk in the cob webs these spiders spin.

Granular cleansing formulas, based on essential plant oils, can be an important part of such a program, too. The natural plant oils in a properly prepared corncob mulch produce a pleasant, clean-smelling environment, and each granule actually “micro-cleans” the tiny spot that it touches. This is particularly important where annoying webs are produced by species of spiders that do not reconstruct their webbing every day. The webs from these spiders can accumulate in voids in landscaping and, besides making an unsightly mess, make it difficult to see everything that is in those areas. If you toss a small amount of such granules into the landscaping voids in your yard, the individual granules attach to the strands of any spider webs there and weaken them, making the webs fall apart naturally over time. The granules also create a micro-environment that does not nurture or attract organisms, such as spiders and their prey, acting as habitat modifiers to produce a pest avoidance zone that is pest-and-pesticide free (a win/win solution, if ever there was one).

I thank Bridget W. for having the curiosity and tenacity that led her to look more deeply into the momentous events taking place in her yard, and the determination that led her to photograph those events for us to see.

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— Questions? Corrections? Comments? BUG ME RIGHT NOW! Telephone  Jerry directly at 512-331-1111, or e-mail [email protected]. You may also register, log in, and leave a detailed comment in the space provided below.