Cobweb

September 30, 2023

We have a laundry room between the garage and the front hall that also serves as our storage pantry.  We have shelves along one side with cans and boxes of food items, as well as laundry and cleaning items on the bottom shelf.  The other side of the narrow room has a washout sink located next to the washer and dryer.  We no longer use this sink cabinet as it has become a storage site for dog snacks.  Many of these treats are bought from the big box store which means some of those treats are in a large box.  Loki’s smaller dog biscuit box sits on top the dryer, but Zena’s larger box of biscuits is stored in the garage.  When I stuck my hand in Zena’s biscuit box several weeks ago, I felt the beginning of a cobweb.  This week the cobweb was more pronounced, and I opened the box to see what was happening inside.  There was a small spider and a prodigious cobweb that stretched around most of the top of the box.

When I looked online, I found the triangulate cobweb spider (Steatoda triangulosa), also called the triangulate bud spider, is a common spider in the genus Steatoda.  Its name derives from the triangle-shaped pattern on the dorsal side of its abdomen.  The species was first described as Aranea triangulosa, by Charles Walckenaer in 1802 but was transferred to the genus Steatoda by Tamerlan Thorell in 1873.  The adult female is 1/8 to 1/4 inch (3 to 6 mm) long, with a brownish-orange cephalothorax (fused head and thorax of spiders), spindly, yellowish legs, and tiny hairs.  The round, bulbous abdomen is creamy in color, with parallel purply-brown zigzag lines running front to back.  This distinctive pattern sets it apart from other theridiids in its habitat.  The triangulate is known as a “useful spider”, as it preys on other types of arthropods, ants (including fire ants), other spiders, pill bugs, and ticks.  It also preys on several spiders believed to be harmful to humans, including the brown recluse (Loxosceles reclusa).  The egg sac of the triangulate is made from loosely woven silk.  It is about the same size as the spider itself and contains approximately 30 eggs.

Like other members of the family Theridiidae, the cobweb of the triangulate is an irregular tangle of sticky silken fibers.  The spider will usually eat for a period but spends most hours developing their sturdy cobweb.  Like other web-weavers, these spiders have very poor eyesight and depend mostly on vibrations reaching them through their webs to orient themselves to prey or to warn them of larger animals that could injure or kill them.  They are not aggressive and only one known case of a human being bitten (envenomation) is recorded.  Their bite will not kill a human unless there is an allergic reaction.  The triangulate is a cosmopolitan species and can be found in many parts of the world, including North America, southern Russia, New Zealand, and Europe.  It is believed the spider is native to Eurasia and has been introduced elsewhere.  The species is primarily a house spider and builds webs in dark corners of buildings and other man-made structures (like Zena’s treat box).

Thoughts:  Ever since a tarantula landed on my ear at Boy Scout camp when I was 12 years old, I have been squeamish about the possibility of spiders unknowingly crawling on me.  That means while I am not scared by seeing a spider I do not like running into cobwebs when I do not know where the spider is.  There were four egg sacs in the cobweb in Zena’s box.  I did not kill the spider but did remove the egg sacs as I did not want another 120 spider babies lurking “somewhere” in my garage building cobwebs.  Fear is often tied to the unknown rather than a known threat, and when we take the time to investigate the cause of our fear it will go away.  This is also true with our fear of other people.  When we take time to get to know and even understand others, we find they no longer make us afraid.  Act for all.  Change is coming and it starts with you.