It's Spider Time!

Thursday, September 3, 2026

Although spiders may seem more visible now, it doesn’t mean they are more numerous (or gearing up for Halloween)! Many hatch in the spring or summer and have been hunting, eating and growing. Once mature, or fully grown, females are usually larger than the males – they need extra energy to lay eggs - and their larger size, and webs, catch our attention. Plus, if a species mates in the fall, the smaller male spiders are on the move and searching for a mate, making them more noticeable as well. Once mating takes place, and the females lay eggs, their life cycle is complete, especially for orb weaver spiders. Just like Charlotte, in the book Charlotte's Web, the female dies. However, some female spiders stick around to protect their egg sac and young spiderlings. Wolf spiders, Pholcus phalangioides, even carry their egg sacs (attached to their bodies) and their young on their backs once they hatch, for about two weeks! (The males die too, possibly ending up as meals for the females, which provides extra nutrition for her developing eggs.)

As the temperatures continue to drop, and the days become shorter in autumn, hardy spider species may search for warmer, sheltered spots. Our houses, and buildings, provide quiet, dark places for them to hide and rest! Cellar spiders, Pholcus phalangioides, are known for remaining active all winter within our basements. Those living outside may die after the first frost but several species produce a type of antifreeze that allows them to survive the colder months. Either way, any spiderlings, or baby spiders, overwintering within their protective silken egg sacks, will hatch in the spring and start the cycle all over again. 

Although much maligned, spiders are amazing and useful animals. They help keep insect populations under control, helping farmers and homeowners alike, and provide food for numerous other animals as well. Spiders are arachnids, a group of arthropods that includes ticks, mites and scorpions. There are over 45,000 species of spiders found throughout the world in a wide variety of habitats. Illinois is home to about 630 species. Spiders range from tiny creatures only a third of a millimeter long to giant tarantulas that have a leg span of over one foot.

While most spiders produce venom, only a handful are dangerous to people. In our area, the Brown recluse, Loxosceles reclusa, currently lives in central and southern Illinois. Northern black widow spiders, Latrodectus variolus, live in the Chicagoland area but are rarely encountered. Spider venom is used to subdue their food, or prey. With the exception of the two spiders mentioned above, the jaws of most spiders are too weak to break human skin. 

As predators, spiders trap other animals in their webs, or actively hunt their prey. They don’t have mouthparts for chewing, so they inject fluids that digest their meals and then they suck out the liquefied insides. In the fall, large female spiders like the Black-and-yellow Garden Spider, Argiope aurantia, sit patiently in the center of their large webs eating anything that gets trapped in the sticky silk.  

This silk, which is produced by all spiders, is a strong, stretchable rope-like material, but not all spiders build webs. Spider silk, which comes from nozzle-like spinnerets on their abdomen, helps wrap up their prey, is used when climbing, and as an anchor, in case of a fall. It's also used to make eggs sacs, find new places to live ("ballooning" - see info below), and of course to make webs. Jumping spiders, like the diurnal, or day active, Bold Jumper, Phidippus audax, which don’t make webs, use silk anchor themselves before jumping. (They were probably the first bungee jumpers!) These non-web building spiders, and others, like the nocturnal Yellow Sac Spiders, Chiracanthium spp, found in our homes, also use silk to make themselves tiny “sleeping bags” to retreat into during the day. You probably have seen the little silken retreats of Sac spiders in your house. They can be found along the ceiling where it meets the wall. 

All spiders have two body parts and eight legs but despite (most) having eight eyes, they don’t see very well. To compensate, numerous hairs on their bodies allow them to feel even the tiniest movements and vibrations. However, the eyesight of jumping spiders and wolf spiders are the exception to this rule. According to the latest research, jumping spiders see more colors that people. Consequently, jumping spiders are most active during the day while wolf spiders are primarily nocturnal. 

Spiders have evolved to live in all sorts of places throughout the world and have even been found on the tops of mountains! The ways in which spiders have tackled the tasks of finding food and shelter, protection and new places to live are ingenious. For example, have you ever noticed lots of shiny silk threads stuck on grass, branches and other objects on a windy day? You were probably witnessing one of the ways spiders disperse to new places, called ballooning. Used mainly by spiderlings, but also by specific groups such as dwarf spiders, this method of movement requires a spider to point its abdomen upward while releasing silk threads to catch the wind and take off, floating on the breeze. They can be carried a few feet or thousands of miles. Although not all of the spiders will survive this turbulent journey, enough will safely land, continuing to make a dent in the pesky insects found outside in our yards, as well as inside our homes!

To learn more about Chicagoland spiders and how you can identify them by the number and placement of their eyes, visit here.