Skip to main content

Bait scent, fishing-line device allow spider to reel in moths

A toadlike bolas spider holds her silken weapon: a sticky ball she dangles and flings at approaching moths.

October 2, 2016

Jim McCormac

A gaucho is a cowboy of the South American pampas. Gauchos are skilled horsemen and effective wielders of an odd weapon known as a bolas. The bolas is a stout cord to which they affix a heavy ball or balls. When hurled accurately, the bolas ensnares the legs of quarry and trips it up.

A group of spiders has been flinging bolas lines far longer than the gauchos.

The bolas spiders comprise a group of about 50 species, all of which occur in the Americas. Thirteen species are found north of Mexico, and four occur in Ohio.

Finding a bolas spider is always a big deal. They’re rare and easily overlooked. It wasn’t until Sept. 3 that I finally clapped eyes on one of these bizarre spiders.

I and others were conducting nocturnal field work in The Nature Conservancy’s sprawling Edge of Appalachia Preserve in Adams County. Suddenly, a roar went up from David Hughes, who is a firefighter and expert photographer. He had found a toadlike bolas spider, Mastophora phrynosoma.

During the day, the toadlike bolas spider rests atop a leaf, looking like an amorphous glob of fungus or gooey bird dropping. From certain angles, it looks rather toadlike. Presumably, would-be predators ignore such an unpalatable-looking mass.

Come dusk, the spider spins a few silken guy wires under leaves and prepares to hunt. She hangs from her support lines and crafts her sophisticated weapon. By rubbing a silken line against sticky secretions generated by her spinnerets, the spider forms a gluey ball.

When all is ready, she suspends the sticky bolas from a silken strand and holds the line with one of her forelegs. The look is much like a fisherman holding a baited rod.

She then emits a fragrance that mirrors pheromones secreted by a certain group of female moths. Eventually a male moth will detect this pseudopheromone and fly in to investigate.

As soon as the amorous moth comes within striking range, the spider flings the bolas and snares the moth. The duped victim is reeled in, dispatched and eaten.

The much-smaller male spiders and young females do not hunt with a bolas. Remarkably, they produce a scent that attracts tiny moth flies, which are seized and eaten.

Lots of weird things transpire under cover of darkness.

Naturalist Jim McCormac writes a column for The Dispatch on the first, third and fifth Sundays of the month. He also writes about nature at


This comment has been removed by the author.
Auralee said…
The Spider

by Robert P. Tristram Coffin

With six small diamonds for his eyes,
He walks upon the Summer skies,
Drawing from his silken blouse,
The lacework of his dwelling house.

He lays his staircase as he goes,
Under his eight thoughtful toes,
And grows with the concentric flower,
Of his shadowless, thin bower.

His back legs are a pair of hands,
They can spindle out the strands,
Of a thread that is so small,
It stops the sunlight not at all.

He spins himself to threads of dew,
Which will harden soon into,
Lines that cut like slender knives,
Across the insects' airy lives.

He makes no motion but is right,
He spreads out his appetite
Into a network, twist on twist,
This little ancient scientist.

He does not know he is unkind,
He has a jewel for a mind
And logic deadly as dry bone,
This small son of Euclid's own.

Popular posts from this blog

The Pinching Beetle, a rather brutish looking bug

The world is awash in beetles, and they come in all shapes and sizes. Few of them can match the intimidation factor of a Pinching Beetle, Lucanus capreolus, though. Those formidable looking mandibles look like they could slice off a finger.

Today was one of those coolly diverse days. I started off down in Fayette County, visiting the farm of a friend. He has restored about 25 acres of wetlands, and the response by the animal community has been nothing short of phenomenal. Blizzards of dragonflies of many species, amphibians galore, and nesting Blue-winged Teal, Pied-billed Grebe, and Sora. Among MANY other things. And all in a short two years. Add water and they will come.

Then, working my way home, I ducked into a Madison County cemetery that has a thriving population of Thirteen-lined Ground Squirrels, and shot images of our native prairie dog. Then, I stopped at a spot along Little Darby Creek, waded on in, and procured some pretty nice shots of various stream bluets and dancers. …

Calliope Hummingbird in central Ohio!

A hatch-year male Calliope Hummingbird strikes a pose. Small but tough, the hummingbird was feeding actively yesterday in 39 F temperatures. It frequents feeders and gardens at a home in Delaware County, Ohio, about a half-hour north of Columbus.

Fortunately, the wayward hummer appeared at the home of Tania and Corey Perry. Tania is a birder, and knew right away that the hummingbird was something special. For a while, the identification was up in the air, which isn't surprising. The Calliope Hummingbird used to be placed in its own genus, Stellula, but has recently been submerged into the genus Selasphorus, which includes Allen's, Broad-tailed, and Rufous hummingbirds. The latter two, especially, are quite similar to the Calliope in subadult plumage. Rufous is the default "vagrant" hummingbird here, with dozens of records and birds turning up annually. There is but one Ohio record of Allen's Hummingbird, from late fall/early winter 2009. Ditto the Calliope Hummi…

Snowy owl photography tactics - and things NOT to do

A gorgeous juvenile female snowy owl briefly catches your narrator with its piercing gaze. It's doing its Linda Blair/Exorcist trick - twisting its head 180 degrees to look straight behind. Owls have 14 neck vertebrae - double our number - which allows them such flexibility.

These visitors from the high arctic have irrupted big time into Ohio and adjacent regions, with new birds coming to light nearly every day. Probably 80 or so have thus far been reported in the state, and some of them have stuck around favored spots and become local celebrities.

I went to visit one of these birds this morning - the animal above, which was found last Friday by Doug Overacker and Julie Karlson at C.J. Brown Reservoir near Springfield. In the four days since its discovery, many people have visited as is nearly always the case when one of these white wonders appears near a large population center or is otherwise very accessible.

And as is always the case, people want to photograph the owls. And th…