Ask The Entomologist

Thoughts on Invertebrate Houseguests

Just last night, my wife asked me to identify a spider that was perched on the wall of our shower. A small thing, its body was only about 3 millimeters long, or about 1/10 an inch. It was an immature spider, and I didn’t manage to get a good look at the layout of its eyes, so I was unable to identify it as well as I’d like. (Many identification resources tend to be more helpful for identifying adult bugs than immature bugs).

While I myself couldn’t identify it to genus level, I shared the observation to iNaturalist, in hopes that somebody with more expertise in spiders would be able to get a closer identification. Regardless of what it is, the chances of its bite and venom being of medical importance are just about nill. The only spider of real medical importance we have here in Montana is the Western Black Widow.

From just in front of the eyes to the tip of the abdomen, about 3 mm.
Sadly, I could only make out the two central eyes, and I’d need to see the others to identify her.

Insects and their kin have been living alongside humans for a very long time – it’s thought that some of our current house-dwelling insects started out as cave dwellers, also living alongside our human forbears. Some early cave art even features cave crickets, as in the Cave of the Three Brothers in southwestern France.

An ongoing project on iNaturalist, “Never Home Alone”, attempts to learn more about our long-term arthropod houseguests. Thus far, this project has led to the discovery of a number of new species – organisms whose behavior “in the wild” is entirely unknown. They’ve only ever been observed and collected from human dwellings.

The scientific paper that this project arose from found that upwards of 100 species of insects could be found in just about every home they surveyed. Defying the stereotype, folks with larger homes in better parts of town had more species of insects, not fewer! Regardless of homeowner’s income, the vast majority of the insect houseguests discovered were non-pest species, and some hadn’t been observed in the region before.

If an entomologist finds that your home is full of bugs, you shouldn’t feel too bad – chances are good that your neighbors’ homes have similar numbers of insects. They’re mostly harmless, and some are even beneficial…. Case in point, at closing time, the spider from the shower had been identified as a harmless variety of cellar spider, Pholcophora americana, who had likely been feeding on moth flies from our drains.

At present, the cellar spider has been relocated to the holly to join our Christmas Spiders.

Myths & Folklore

The Christmas Spider, an Eastern European Legend

Many cultures have their own unique Christmas ornaments… When I was little, my folks had a straw goat ornament from Finland, a “Joulupukki“, or “Yule Goat”, a representation of the harvest season’s spirit – something that made an appearance when folks celebrated the return of the light. They also had a clay Christmas Pig ornament from Germany as well – representing the feast that poorer folks would make, slaughtering their one pig for the midwinter festivities.

Yule Goat

Both goats and pigs feature in winter solstice holiday traditions all the way back to pagan times. However, the Christmas Spider, a decoration and legend more common in Eastern Europe, has a relatively recent origin.

Christmas Pig

There are a number of tales explaining why spiders deserve a place on our Christmas trees, but here are two of my favorites.

As we’ve all heard tell, Jesus was born in the town of Bethlehem, perhaps in a cave. Shortly thereafter, Mary & Joseph fled to Africa with the Christchild, to escape the soldiers of King Herod. In their flight, it is rumored that they hid in caves to avoid the pursuing soldiers. In one case, the soldiers are said to have been close on their heels… and the holy family was saved by spiders, who swiftly covered the entrance of their cave with webs. When the soldier sent to scout their cave saw the webs, he decided that nothing had been in that particular cave recently, there was no need to waste time checking it. In recognition of those ancient Israeli spiders’ good deed, some people place spider ornaments on their Christmas trees… and the tale has even made its way to the pages of a children’s book.

Sometime thereafter, in the not-so-distant past, somewhere in the Ukraine, a family was preparing for the winter holidays. They cleaned the house in preparation for decorating it. Of course, being thoughtful people (and not wanting bad luck) they made sure to not harm spiders when they removed their webs. Once that was taken care of, they put their decorations up, and took a well-deserved rest.

Once all the humans had all gone to sleep, the spiders scurried out from their hiding places. Or perhaps, just perhaps, the spider egg sacs brought in on the tree hatched in the warm house. Regardless of how the spiders got there, they began to investigate the tree.

The spiders marveled at its decorations – so different from the trees outside! In an attempt to contribute, the spiders coated it in their webs… Unfortunately, many humans don’t think spiderwebs make good decorations. Later on in the night “Дід Мороз” – Father Frost appeared (or Father Christmas, Saint Nicholas, or the Christ Child… there are many variant tales). Regardless of who the holiday wonderworker was, he saw what the spiders had done, and turned all their webs into skeins of silver and gold! And thus the very first tinsel was created. Born of spiders’ desire to contribute to the winter celebration.

Here are some instructions if you’d like to make a Christmas Spider of beads and wire for your own family’s tree, after the Ukrainian tradition. As for me, my Christmas spiders, my pavuchky” – little spiders, are origami, folded from bright foil, and hidden among the branches.

One of this year’s origami Christmas Spiders.

Ask The Entomologist

Harvestmen, or Daddy-Long-Legs

Earlier this week, I met a Harvestman while making supper. It had stowed away on some kale from the garden, and was still walking about on it… even after a week or so in the refrigerator.

The refrigerated Harvestman was promptly photographed and released in our garden’s cold frames.

Harvestmen have a rather well-known urban legend. Perhaps you’ve heard people say that “they’re the most venomous spiders in the world, but are harmless to humans because their fangs are too small to puncture our skin.”This myth is mostly untrue. While Harvestmen are harmless to humans, they are NOT spiders – they’re closer kin to scorpions and mites. Additionally, they don’t have venom, though they do have some chemical weapons and chemical defenses. Some species, however, rely more on physical armor than chemicals.

This Ecuadorian Harvestman sees no reason to limit itself:
it has spiny armor and is putting chemicals on an arm, which it will then use as a whip!

While many people call Harvestmen “Daddy-Long-Legs”, this common name is rather vague, and I try not to use it. It can also refer to Crane Flies and Cellar Spiders, and I prefer being specific. Incidentally, the harvestmen myth is equally untrue for those two organisms as well.

Unlike most other arachnids, Harvestmen aren’t primarily hunters. Actually, many Harvestmen prefer to eat things that are already dead… They’re great scavengers, happy to eat dead vertebrates, dead invertebrates, and even droppings. One European species has been claimed to hang about bee hives, eating the dead worker bees that worker bees on the custodial shift are tossing out.

Harvestmen are beneficial for our gardens though, because they can and do hunt small insect pests such as springtails. They use their tiny little pinchers and fancy chemical glue to catch their prey. If you’d like to see their feeding behavior yourself, I’d suggest waiting by a porchlight at night – I’ve found that they like to ambush and eat little moths. If you’re a bit more hands-on, Harvestmen are easy to keep in captivity, and could make a great science project (drop me an email if interested in more details).

As for why my Harvestmen was still alive in the refrigerator, these invertebrates tend to be Cold-Tolerant and Freeze-Avoidant. They’d prefer to be warm, increasing their odds of survival, so in autumn one can find large aggregations of Harvestmen. Sharing warmth, sheltering from the elements, and trying to survive the winter. This overwintering behavior frequently happens in caves, though in eastern North America, Harvestmen also overwinter in leaf litter.

A disturbed aggregation of overwintering Harvestmen from a cave in Northern Tennessee.

What have you observed Harvestmen doing?
Hunting? Mating? Overwintering?

Ask The Entomologist, Community

Ask the Entomologist: Massive spider

This past week I had an identification request from a bit closer to home. This giant spider was perched right below one of our windows and my wife wanted to know what it was.

Araneus gemma, the Gem-Shaped or Cat-Faced Spider.

While I’d seen and admired her webs before, this was the first time I met the web’s weaver. She must have spent most days hidden behind the window AC unit. Revealed now that we’d removed it, now that fire season and the heat of summer seem to be past.

As an entomologist, I have to say that I’ve met larger spiders, but this is the largest one I’ve seen up here in Trego. She’s an Orb-Weaver, a spider in family Araneidae. These are classic storybook spiders, straight out of Charlotte’s Web. When you see those beautiful wheel-shaped webs, big and round, full of droplets from the morning’s dew, these are the spiders responsible.

I rather like Orb-Weavers – these spiders have pronounced sexual dimorphism. Females are often far larger than males – routinely twice the size, sometimes up to four times as large. Our A. gemma was quite large for her species, a 2/3 inches across the abdomen, and over an inch in length if we measure from the tip of her abdomen to her outstretched legs.

At over an inch in length, she’s one of the largest spiders I’ve met here.

As far as medical importance is concerned, the Gem-Shaped Spider’s bite is harmless to healthy humans. Additionally, I’ve handled many related Argiope orb weavers, and have never been bitten by them, so I don’t think receiving a bite from one of these is likely. However, if you or your loved ones are immunocompromised, elderly, or very young, more caution may be merited.

Which common name do you prefer – the Gem-Shaped Spider or the Cat-Faced Spider?