Araneus diadematus | Bugging You From San Juan Island

I’ll Have Some Salad Said the Spider!

Posted on April 29, 2022 by "BUGGING" YOU FROM San Juan Island 2 comments

Did you know spiders don’t just eat bugs? That’s right! You can amaze your friends when you share your knowledge about our eight-legged friends chowing down at the salad bar.

Researchers have observed various species of spiders (over 60 species worldwide) feeding on plant foods to supplement their invertebrate prey (Nyffeler et al. 2016). What exactly does this mean? Are they going to eat the leaves of your garden plants? Nah! Not to worry. They are primarily pest predators in your garden – little helpers to keep those aphids away.

Spiders have long been thought to only consume insects and other invertebrates. However, in recent studies, we are finding this isn’t entirely the case. Observations of spiders foraging in nature has broadened our understanding of the diets of our arachnid friends. Our prior assumptions were incorrect. Spiders actually eat pollen grains, floral and extra-floral nectar, Beltian and Müllerian bodies (structures produced by plants on their leaf tips or petioles, plant sap, honeydew (a plant-derived sugar produced by homopteran insects like aphids), seeds, spores, and even the vegetative material in the guts of their invertebrate prey (Nyffeler et al. 2016).

Tree Pollen collected in ground vegetation

I found several papers on this topic, but one of the most interesting to me talked about how pollen is an important source of protein for spiders in early spring when prey may be scarce. It also pointed out that pollen is a critical food source for newly hatched spiderlings. Baby Orbweavers for instance. We have these here in the San Juans. They are delightful!

Orb Weaver Spiderlings on my garden chair

Well, since the pollen floats through the air, quite a lot will stick to webs, landing exactly where the little spiders can easily access it. Smith and Mommsen (1984) even found that Orb Weaver spiderlings doubled their life expectancy by eating pollen. Eggs and Sanders (2013) concur that pollen is an important dietary supplement for Orb Weaver spiders and found that juvenile orb weaving spiders’ diets consist of approximately 25% pollen.

So, now you know! Our little spider friends, or some of them at least, are more complex than we knew. It’s a good reminder about how important it is to eat a varied and healthy diet. We can put this into practice ourselves. Good nutrition is vital for health and survival – for all living beings.

References

Eggs B, Sanders D (2013) Herbivory in Spiders: The Importance of Pollen for Orb-Weavers. PLoS ONE 8(11): e82637. https://doi.org/10.1371/journal.pone.0082637 https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0082637

Nyffeler, M., Olson, E. J., & Symondson, W. O. C. (2016). Plant-eating by spiders. The Journal of Arachnology, 44(1), 15–27. http://www.jstor.org/stable/24717357 https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjp9dWF97n3AhXQLTQIHTh1CF0QFnoECBsQAQ&url=https%3A%2F%2Fwww.jstor.org%2Fstable%2F24717357&usg=AOvVaw0mZYSQxF6kMinvaqvgB4UT

Smith RB, Mommsen TP. Pollen feeding in an orb-weaving spider. Science. 1984 Dec 14;226(4680):1330-2. doi: 10.1126/science.226.4680.1330. PMID: 17832631. https://www.science.org/doi/10.1126/science.226.4680.1330

Araneus diadematus, My Cross Orb Weaver friend named “Louisa.”

Posted on November 6, 2021 by "BUGGING" YOU FROM San Juan Island 2 comments

I first spotted this beauty on October 1, 2021 while I was taking a walk along our road on San Juan Island. There was a cluster of sun loving mullein (Verbascum thapsus) mixed with one or two thistles (probably Canada thistle) growing along the road. The glistening silk threads woven between them drew me over to investigate. There were several Cross Orb Weavers sharing the space here, but one of these was not like the other. The spider that caught my attention was quite a bit darker than the others. Describing it as brown just doesn’t do it justice. Brown sounds much too plain. She was a lovely brunette amongst a few redheads!

~ After you’re done reading, come back and check out this link to learn more about pigmentation in arachnids – https://www.bio.fsu.edu/~miller/Spider%20photos/spider_literature/color%20in%20spiders%20papers/Oxford_Gillespie_20xx.pdf

Since I often enjoy walking on our road on sunny days, I started looking for her when I passed her home – the Mullein “apartments.” It wasn’t just the spiders enjoying the sunny housing complex, but these units housed a few other species as well. I found some Stilt Bugs (Neoneides sp.) and some Pentatomidae hiding in the fuzzy star shaped trichomes (little hairs) of the Mullein leaves.

Now that autumn has ushered in falling leaves, falling temperatures, and a good bit of rain, I thought of my friend Louisa, the Orb Weaver out in the cold. Had she managed to find a sheltered spot to survive the recent storms? Several times over the past two weeks I’ve looked for her, but she was just gone. Since the lifespan for this species is only a year or less, I suspected she’d reached her end with our last dip in temperatures, gusty winds, and precipitation. I held out a tiny bit of hope though. Just a bit!

Today (November 6, 2021), my husband and I walked our road. It was sprinkling and the precipitation was cold. When we got down to the point on the road to turn around, shortening our walk to just the point where the old cabin used to be, I asked him to wait one second while I looked one more time at that patch of Mullein and the drying stand of thistles.

As I bent down to look closely, I saw a single strand of silk. Examining the attachment and following closely, it led me to Louisa. She was tucked under the dried nodding inflorescence of the thistle. Once a purply-pink sugar treat for pollinators, the now nodding blooms have been repurposed into a thatch roof to keep this little spider dry.

I’ve thought about relocating her so the county doesn’t mow her when they scalp the roadside vegetation. It is bound to happen at some point. For now, I’m going to leave her be, and just keep a close eye on her. Maybe I’ll make a sign! Be Nice to Spiders. ❤️ Louisa lives here!

Fun Fact! Did you know that 25% of the diet of Orb Weaver spiderlings is pollen? Check it out. Article linked in my list of sources below.

Araneus diadematus (Cross Orb Weaver) October 1, 2021 – San Juan Island, WA

Araneus diadematus (Cross Orb Weaver) October 13, 2021 – San Juan Island, WA

Araneus diadematus (Cross Orb Weaver) October 16, 2021 – San Juan Island, WA

This is “Louisa,” the Land Bank Orb Weaver Spider. She lives on a Mullein plant alongside the road. I’ve been watching her since October 1, 2021. Hoping she will not become a casualty of San Juan County’s pre-winter roadside mowing. She’s also an expecting mom!

Araneus diadematus (Cross Orb Weaver) November 6, 2021 – San Juan Island, WA

References and further Reading –

Eggs B, Sanders D (2013) Herbivory in Spiders: The Importance of Pollen for Orb-Weavers. PLoS ONE 8(11): e82637. https://doi.org/10.1371/journal.pone.0082637

Gucker, Corey L. 2008. Verbascum thapsus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/plants/forb/vertha/all.html [2021, November 6].

Horton DR, Lewis TM (2003) Numbers and types of arthropods overwintering on common mullein, Verbacsum thapsus L. (Scrophulariacae), in a central Washington fruit-growing region. Journal of the Entomology Society of British Columbia 100, 79–87.

Oxford, Geoff & Gillespie, Rosemary. (1998). Evolution and ecology of spider coloration. Annual review of entomology. 43. 619-43. 10.1146/annurev.ento.43.1.619.

Riaz, Muhammad, Zia-Ul-Haq, Muhammad and Jaafar, Hawa Z.E.Common mullein, pharmacological and chemical aspects. Revista Brasileira de Farmacognosia [online]. 2013, v. 23, n. 6 [Accessed 6 November 2021] , pp. 948-959. Available from: <https://doi.org/10.1590/S0102-695X2013000600012>. ISSN 1981-528X. https://doi.org/10.1590/S0102-695X2013000600012.

Turker AU, Gurel E. Common mullein (Verbascum thapsus L.): recent advances in research. Phytother Res. 2005 Sep;19(9):733-9. doi: 10.1002/ptr.1653. PMID: 16222647. https://onlinelibrary.wiley.com/doi/10.1002/ptr.1653