Gas Spyders???

Hi Everyone,
Can anyone tell me what "Gas Spyders" are???? I believe that there was mention of them on this site, but I can't remember where I heard of them.
Thanks,
Fire Bug

Gas Spider story: I doing a final Mechanical inspection on a new home Every thing is going fine till I get to the gas hot water heater It goes no for a few minutes than shuts off So the inspection fails The plumber figures it is a defective unit and goes threw all the work of removing it and re-installing the new replacement. Fires it up and the same thing happens it shuts off. The next day the Gas Company is going to dig up the line threw the street and new sodded lawn. While removing the new gas hot water heater, they begin
Removing the feed line. Someone look into the line and saw the gas spider and web in the line. That’s right tiny spiders can crawl into gas lines and form webs. The webs restrict the gas flow and cause the appliance to act erratic. Bad pilot flame, appliance not getting enough gas volume. Not firing as it should and even can cause it to shut down. Gas spider

Spider mites are drawn to the sent of natural gas and lp. As Elk pointed out, they like to nest and build webs in gas lines. This is one of the arguements why you should leave the pilot light burning on your gas fireplace in the off season.