Halloween--Spider Season

Banded Garden Spider

Halloween is the time of year for tricks or treats and frights of all kinds. For many of us with arachnophobia, spiders are a fright no matter what time of year it is.

However, in autumn it often seems like we are under siege by diminutive 8-legged creatures. Everywhere you look there they are! There is a reason for this. The spiders have been around all year in miniature form; therefore we don’t notice them. The tiny spiderlings spend all season growing, and by September and October they are large and much more visible. When we also factor in that they are looking for places to spend the winter, like our homes, we are much more likely to run across one.

Where does this fear come from? Are we born with it? Experts say no, so why are we afraid? It comes from many factors in our lives. Maybe your Aunt Bessie feared them and taught you the same fear, or perhaps your grandpa Joe thought they were all dangerous and passed his sage wisdom onto you, and now you carry the same misguided idea. Or....maybe....it was from all those cheesy movies you couldn't resist watching. Whatever the cause, it is a fear that can become all consuming and create anxiety attacks in those afflicted which such a terror inducing phobia.

Burrowing Spider

The film industry has created an unreasonable fear of anything 8-legged, furry and creepy. While I do agree spiders are not exactly cuddly, they are far from the evil masterminds that perpetrate all sorts of woes against mankind. In fact, the opposite is true, spiders should be considered a friend to humans. They are insect eating machines and have devised all sorts of unique ways for capturing nuisance bugs. Many spiders build easily recognized webs that often hang from the eaves of our homes, or perhaps from the plants in our gardens. Walking into one of these webs as you stroll around your yard or hike a beautiful trail, will turn you into a kung-fu champion as you invent moves never before seen to shake an unseen, eight-legged invader you are convinced is now attached to your person.

Other spiders stalk their prey, much like a cat stalks a mouse. Pouncing on their victim at the last possible second and subduing them with great speed and dexterity. Still other spiders build "trap doors" in the ground and pull their victim into their lair to meet an untimely death.

With over 300 species of spiders living in Missouri, there is no shortage of encounters to be had. Especially in autumn before the first freeze arrives, you will see them, in what seems like, everywhere. Spiders come well-equipped for hunting, most species possess eight eyes, giving them incredible eyesight (at least within a reasonable distance). There are a few species, such as the brown recluse, that only have six eyes, but this does not deter them in the slightest where hunting is concerned.  Nearly all spiders have a venom cocktail unique to them and can deliver their toxic brew through fangs which are often much larger than would seem necessary for the job.  Most, but not all, spider venom is harmless to humans. The venom is only deadly if you are a six or eight-legged creature destined to be dinner for one of these master hunters. In fact, most spiders have fangs too weak to bite through human skin. Some of the larger spiders would be capable of biting us, but rarely do unless mishandled.

Brown Recluse

Black Widow

 

 

 

 

 

 

                                                                               There are two spider species in Missouri that may have medically significant consequences to humans, should you be bitten. Brown Recluses have been given a bad rap for many years. Yes, they do possess venom that can potentially be harmful to humans and may cause necroses (skin rotting).  If left untreated, these wounds can become infected and cause a life-threatening situation. This would be in EXTREME CASES! Most recluse bites go unnoticed by people, their fangs are so sharp that the bite is generally not felt. Venom typically causes skin irritation and itching at the sight of the bite, and nothing more. On average, about 10 % of the cases, a severe reaction will occur, and medical treatment will be required. The bite itself is not fatal, unless you happen to be incredibly allergic to the proteins in their venom. It is the secondary infections from leaving the bite untreated that could result in death. If they are in your home, or somewhere you do not want them to be, try to relocate them outside far away from their original location. One key to identifying these spiders is the "violin" shape on the back of the head. It is this unique marking that earned them the nickname Fiddle Spider.

Missouri is home to three species of black widows, and the female of each species has a highly toxic venom.  Black widows are very secretive and prefer to avoid humans, even though they tend to build messy little webs in the rafters or corners of buildings, basements, cellars, and other man-made structures. You will also find them under rocks, in wood piles, even in the holes in golf course greens. The bite from one of these spiders can be a nasty experience. It is said that their venom is ounce-for-ounce more toxic than a rattlesnake. I know of no deaths that have occurred in Missouri as a result from a bite of one of these glossy black beauties, but I've heard tales of many painful encounters.

The poison of the black widow spider affects nervous system function. The bite causes severe pain in the vicinity of the bite, accompanied later by dizziness, nausea, blurred vision and breathing difficulty. A physician should be contacted immediately. Death is not likely to occur unless you have an anaphylactic reaction to the venom. Black widows rarely leave their web, preferring instead to let food come to them. Bites typically occur when coming into direct contact with the web or pinning the spider against your body. Black widows are predominantly a nocturnal species and will rarely be seen during the day, unless you happen to turn over a rock or log and find one. 

 

Wolf Spider

I remember when I was a small girl my grandfather found a very large spider in his basement. He had no idea what the spider was, so he took it to the local college and asked a biology professor to identify it. The professor informed my grandfather it was a harmless wolf spider and that he should place it back in the basement and let it do what they do best, eat bugs. Dutifully, my grandpa returned home, and quietly retreated to the basement and secretly let this spider go. Winking at me, he said, "this will be our little secret". Knowing full well if my grandma got wind of a spider the size of a silver dollar living in the basement, he would never have clean clothes to wear again. I figure my grandpa had the right idea. So, all of you borderline arachnophobes out there; try not to buy into what the movie producers what you to believe. No giant flesh-eating monster spiders are going to attack you while you sleep. You are safe. For now.

 

Trapdoor Spider

American Sand Wasp

If you, like me, enjoy a visit to the local river, then you have probably encountered the beautiful American Sand Wasp. The ASW is commonly found along rivers, streams and other areas that feature sandy/loamy soil, sand dunes, and other areas of loose sandy soils. They are nearly an inch in length, with a distinct black and white banded abdomen, green eyes (that may look blue or blue-gray in certain light), clear wings with dark veins, and mostly yellow legs. The head and thorax are covered in short white hair.

Females are gregarious nesters, meaning they will often nest in the same area as other females. These areas may include the nesting sites of as many as fifty females and are used year after year. Females begin excavating a nest by scraping soil with their front legs and passing it underneath their bodies. Once the shallow nest is dug, the female will tamp down the soil mounded up around the entrance in an attempt to hide the opening. Each nest may contain one to three chambers. At this time, the female begins looking for prey to provision her offspring with. They prey almost entirely on flies, including houseflies, deer flies, and even mosquitoes. She will sting the fly to paralyze it and then carry it held tightly to her body and fly back to the nest. By using subtle landscape markers, she can consistently locate her nest, whereas by comparison we humans struggle to locate our car! Once inside the chamber, the female will lay a single egg on the paralyzed fly. The newly hatched wasp larva will feed on the fresh meat so lovingly provided by its mother. The female participates in progressive feeding, meaning she will continue to capture and provide prey for her developing larvae until they pupate. She may also shift between progressive feeding, and mass feeding, meaning she may also provide numerous paralyzed fly dinners at once for her larvae. When those meals have been consumed, she will continue to provide food. Each larva may consume up to twenty-four fly dinners before forming a pupa. If she has formed three chambers, with three separate larvae, that is seventy-five fly dinners provided to hungry wasp larvae!

Once the wasp larvae have pupated, the female will close that chamber and excavate an additional chamber within the nest and provision it with fly prey for the second generation of wasp larvae. Occasionally she will close off the nest entirely and dig a completely new nest nearby. Most of their adult life is spent nest building, nest provisioning, and hunting for prey for developing larvae. If one were to do the math and calculate how many nesting females are at a given nesting aggregation, and every female capable of double broods each season, and they may form and maintain up to three chambers within each nest, it is conceivable they would capture, kill and feed their offspring more than 5,000 flies! Talk about biological control!!

Males will emerge from the nesting chambers first and spend several days flying rapidly and erratically over the ground above the aggregation area. Occasionally they will land and use their feet to sense vibrations under the soil, signifying females moving around underground. Males may also be able to use their antennae to pick up the subtle pheromones emitted by emerging females. Within a few days of the male’s arrival, the females emerge, and the melee begins! Males may pounce on virgin females as soon as they leave the nesting chamber, or if the females manage to take flight, a male gives chase and tries to win the female's favor. If she is receptive, the pair will quickly leave the chaos ensuing around the aggregation site and set off alone for mating. If by some chance they are knocked to the ground, another male still in the area may force the breeding male away from his female and take over breeding rights.

Like nearly all animals in nature, there are other animals preying on them, and these wasps are no different. Many flies, in a form of turning-the-tables on your enemy, prey on these wasps. Satellite flies, cuckoo flies and others all prey on sand wasps. The observant fly waits for a passing sand wasp and will follow the wasp to the opening of the nesting site. Once the fly is inside the larval chamber, it will lay an egg on the wasp larva or on the provisioned prey brought in by the female wasp. It is believed by many wasp experts that the female is instinctually programmed to over-provide for her offspring to give a higher chance of survival to her progeny. It has been observed by scientists that the fly predator and the wasp larva can and have developed side-by-side in the nest to adulthood, much to the chagrin of the female wasp. She has unwittingly become the provider for her own offspring as well as to the fly who would just as soon eat her young. Such deception!

These busy little wasps are solitary and not known to be aggressive in any way toward humans, pets or livestock. Occasionally they set up nesting aggregations near ball parks, playgrounds and other areas where children and families are known to be. Control measures are not recommended, since they pose no real threat to people. It is best to stay away from those areas for four to six weeks which will allow these wasps to finish their lifecycle. As humans, a little tolerance goes a long way, and if we just remind ourselves these pretty little wasps are killing thousands of potentially dangerous and definitely pesky flies and mosquitoes, making our life much healthier and our outdoor time more enjoyable.