Funnel Weaver

In the back corner of the barn, I found this wonderful Funnel-web Weaver spider.  It’s a species of the genus Agelenopsis, but I’m not certain which.  My reference book lists several species that might be found in this area.  Identification to the species level involves examination of the spider’s genitalia and that means having the specimen quietly resting beneath some magnifying device.  I usually don’t kill things just to find out what they are.

The spider sits at the mouth of its protective funnel and awaits an indication that some hapless insect has wandered onto the web.  It has chosen a great location.  Flying insects are always entering the barn and then getting trapped by the window glass.  There should be a steady supply of food falling into the web.

The web is constructed as a large flat surface roughly oriented in a horizontal plane.   Movement on this surface alerts the spider to potential prey and it rushes out to make its capture.  The web is not sticky, so insects on the web can freely escape if not quickly captured by the spider.

In order to make escape from the web more difficult, a network of web fibers form a random pattern over the top of the flat surface.  Insects trying to fly or jump to safety are deflected back into the web by the fibers.

The neatest thing about this particular web is the position of the funnel.  The funnel is normally built in a location that offers protection to the spider, so it’s unusual to have an unobstructed view.  This funnel is fully exposed on one side.

The spider spends most of its time in the funnel.  From this position, it can pick up vibrations from the web that indicate the presence of some insect prey.  Captured insects will be brought into the funnel where they are consumed by the spider.

At the rear of the funnel is the garbage dump.  Remains of earlier meals hang suspended in loose webbing.  Excess prey could also be stored here to future consumption.  I pulled out a couple of the bodies and found they were nothing but empty shells.  I didn’t see anything there that looked to be a suitable meal.  I’ll leave the web in place until the spider departs.

Spider

Late summer is a great time to find big spiders. This specimen was found in a large web built in one of the prairie openings. This is a species of the genus Agelenopsis, one of the funnel web builders.

Luckily for this spider, we’re experiencing a major drought, because he chose the center of a major drainage way as the location for a web. A major rain would certainly remove the web and probably the spider.

Funnel web builders are very common and their webs are easily recognized by the tunnel of webbing that connects the web sheet with the spider’s hiding location. The spider hunts insects that fall upon the web sheet.

The sheet on this particular web was nearly three feet across. The silk used in construction of the sheet is not at all sticky. The spider senses vibrations in the web and must quickly catch the prey before it moves off.

Species of this genus increase the effectiveness of their webs by building a tangled maze of single web strands over the top of the sheet. These strands make it difficult for flying insects to leave the sheet and make it easier for the spider to catch its meal. I love finding these super sized webs and watching the big spiders prowl the sheet.