Category: Invertebrates

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Spider Silk

Orb Spider Web
Contains 3 Types of Silk

Courtesy & Copyright 2011
Terry Greene, Photographer

Spider silk has long been of interest to scientists and engineers for its incredible strength. Silk can be, by weight, a stronger fiber than steel or Kevlar. But new research has discovered that the strength of the individual fibers does not explain the durability of a web, which can remain functional after sustaining extreme stress. The web’s overall design adds to silk’s durability to create a truly functional product.

Spiders utilize silk for many different reasons – transportation, lining burrows, protecting and securing egg cases, and of course for catching prey. Amazingly, an individual spider has the ability to manufacture several different types of silk, which are used for different purposes. In a typical orb-style web there are at least three kinds of silk at work. One is strong and dry, making up the ‘spokes’ of the web. These are the strands upon which the spider itself moves around, so as not to get stuck in its own trap. The strands which create the characteristic spiral pattern are actually made of two types of silk – one is a fine, stretchy fiber, and the other a sticky, glue-like substance. Together, these two silks make up the part of the web responsible for snaring prey.

Another important property of silk is that when stretched the fiber stiffens. As more pressure is applied, the properties of the silk change, allowing it to become stretchy and flexible. If still more pressure is added, the silk stiffens again, until finally it breaks. Originally, this stiff-stretchy-stiff response to stress was viewed as a weakness, but when analyzed as part of an interconnected web, that’s not the case. A team of scientists from MIT noted that webs could be subjected to a lot of force with only minimal damage. Whether the force was localized – for example while ensnaring a large insect – or more widespread over the entire surface – such as pressure from strong winds – the damage incurred by the web was minimal. Only the individual strands that endure the most pressure break, while others stiffen, flex, and remain intact.

Localized damage allows the spider to more often than not simply repair a web instead of abandoning it and starting over. Creating silk and weaving a web is a costly process for a spider – it takes up a lot of the arachnid’s energy. The ability to simply patch the broken parts is a more efficient strategy which requires less energy expenditure and fewer materials than weaving a new web.

Figuring out how to mimic this response to stress on a material could be infinitely useful in the human world. Imagine a skyscraper in an earthquake that fails in one small place where the forces are strongest – not in its entirety as is currently the case. That same earthquake-damaged building might also need only minimal repairs, saving time, money, and materials. Oh the lessons we could learn from one of nature’s smallest creatures…

Thank you to the Rocky Mountain Power Foundation for supporting the research and development of this Wild About Utah topic. For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.

For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.

Credits:
Images: Courtesy & Copyright 2011 Terry Greene
Text:     Andrea Liberatore, Stokes Nature Center in Logan Canyon.

Additional Reading:

Chandler, David L. (2012) How Spider Webs Achieve Their Strength. MIT News Office. Available online at: https://web.mit.edu/newsoffice/2012/spider-web-strength-0202.html

National Science Foundation press release (2012) A Spider Web’s Strength Lies in More Than its Silk. Available online at: https://www.nsf.gov/news/news_summ.jsp?cntn_id=123041

Law, Steven (2012) Curious Things About Spider Webs. Available online at: https://www.ksl.com/?nid=968&sid=20488145

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Utah Paper Wasps

Adult Poliste Paper Wasp, Courtesy and Copyright 2009 Jim Cane - All Rights Reserved
Adult Poliste Paper Wasp
Copyright © 2009 Jim Cane

We credit the Chinese with inventing paper 2000 years ago, but some social wasps have been making their paper nests for eons. Species of paper wasps are found throughout Utah.

The burly bald-faced hornet workers are patterned in black and white. They place their grey, basketball sized paper nests in tree branches.

Bold yellow and black striped Yellowjackets are the persistent unwelcome guests at summer picnics. They too wrap their round nests in an envelope of paper, but typically place it in a shallow underground chamber. Within the paper envelope, both hornets and yellowjackets have a muti-tiered stack of paper honeycombs, like an inverted pagoda.

Open-faced nest of Polistes  paper wasp with grub-like larvae, Courtesy and Copyright 2009 Jim Cane - All Rights Reserved
Open-faced nest of Polistes
paper wasp with grub-like larvae
Copyright © 2009 Jim Cane

Our most familiar paper wasps belong to the genus Polistes. These are the reddish-brown spindly looking wasps. They make their simple paper nests under your home’s roof eaves and deck railings. A Polistes nest consists of a single inverted paper honeycomb suspended from a stiff, short stalk. There is no paper envelope, so you can readily see the hexagonal paper cells. Around your yard, look for the workers scraping fibers from weathered wood surfaces. Workers mix the chewed fibers with saliva and water, carry the ball of wood pulp home, and add it to the thin sheets of their paper nest. The nest is their nursery, where you can see the queen’s tiny sausage shaped eggs and the fat white grubs. The grubs are fed by their sisters, the workers, who scour the surrounding habitat for insect prey or damaged fruit.

The enclosed nest of the bald-faced hornet Copyright © 2009 Jim Cane - All Rights Reserved
The enclosed nest of the
bald-faced hornet
Copyright © 2009 Jim Cane

Utah has been invaded by the European species Polistes dominula. These interlopers are displacing our native Polistes. Where these European Polistes wasps are a stinging nuisance, you can easily dispatch them at their nests with a sprayed solution of dishwashing detergent and water. Thus stripped of its clever defenders, take the opportunity to admire their homes of paper.

This is Linda Kervin for Bridgerland Audubon Society.

Credits:

Photo: Courtesy and © Copyright 2009 Jim Cane

Text: Jim Cane, Bridgerland Audubon Society

Additional Reading:

https://extension.usu.edu/files/publications/factsheet/yellowjackets-hornets-wasps09.pdf

https://ohioline.osu.edu/hyg-fact/2000/2077.html

https://insects.tamu.edu/fieldguide/cimg348.html

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Antlions and Tiger Beetles

Ant Lion pit
showing loose sides that slide victims
to awaiting jaws at the bottom

Courtesy & Copyright,
Jim Cane, Photographer

Courtesy Wikimedia
Licensed under
GNU Free Documentation License

Lions and tigers in Utah. Oh my! But fear not unless you are an insect. Ant lions and tiger beetles are fierce, diminutive predators. They are not related to each other and the adults look very different, but the larval stages behave in very similar ways. Both await their prey in earthen lairs.

The conical pits of antlions are found in dry, soft sand, frequently under trees, rock overhangs or house eaves. The larvae dig their pit by crawling backwards in a spiral, plowing with their abdomen. The slope of the sides reaches the angle of repose, which is the steepest angle that the sand can lie before it collapses from a slight disturbance. They embed themselves in the sand at the bottom of the pit with their enormous mandibles open like a bear trap. Any small insect that inadvertently steps over the edge of the pit will tumble to the bottom into waiting jaws.

Tiger beetle larvae also await their prey in a burrow, but theirs is a narrow cylinder. The adult female inserts her eggs in the soil. The young larva uses its formidable mandibles to loosen the surrounding dirt, pushing it to the surface with its head and thorax. The larva’s lower back has a prominent hump with two pairs of large hooks. With these, it anchors itself to the burrow wall, its mandibles poised at soil level. Woe to the insect that walks nearby.

The adults of these two underground predators differ in both appearance and lifestyle. The adult antlion resembles a damsel fly with two pairs of long, transparent wings and a weak, nocturnal flight. The adult does not feed and only lives about 3 weeks. Conversely, the diurnal adult tiger beetle is an aggressive, mobile predator. For its size, it is the fastest running insect. It runs so quickly that it cannot see its prey, so sprints and stops repeatedly to track its intended victim. Tiger beetles come in diverse colors and patterns including bright, iridescent greens and blues. In Utah, look for them on bare ground, such as trails in open country or on dunes.

This is Linda Kervin for Bridgerland Audubon Society.

Credits:

Images: Courtesy and Copyright Jim Cane
            And Courtesy Wikimedia
Theme: Courtesy & Copyright Don Anderson Leaping Lulu
Text & Voice: Linda Kervin, Bridgerland Audubon Society

Additional Reading:

Other Wild About Utah Pieces by Linda Kervin

Tiger Beetles:

https://askabiologist.asu.edu/explore/chasing-tiny-tigers

A field guide to the tiger beetles of the United States and Canada [electronic resource] : identification, natural history, and distribution of the Cicindelidae / David L. Pearson, C. Barry Knisley, and Charles J. Kazilek New York : Oxford University Press, 2005. (via Amazon) https://www.amazon.com/Field-Beetles-United-States-Canada/dp/0199367175/
https://en.wikipedia.org/wiki/Tiger_beetle

Antlions:
https://bugguide.net/node/view/137
https://www2.palomar.edu/users/warmstrong/pljuly97.htm

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The Migratory Locust in North America; a post mortem

The Migratory Locust in North America; a post mortem
Rocky Mountain Locust were similar
to this Large Grasshopper
Melanoplus sanguinipes
Photo#215400
Copyright © 2008 Lynette Schimming
As found on www.bugguide.net

Vast migratory swarms of flying grasshoppers, or locusts, have periodically scoured arid parts of Africa and the Middle East since Biblical times, devastating crops and causing famine. But did you know that during the 19th century, American homesteaders were likewise plagued by migratory swarms of grasshoppers? The largest swarm passed through Nebraska in June of 1875; it was 110 miles wide, 1800 miles long and more than a 1/4 mile thick, taking five days to pass overhead. It remains the world’s largest recorded insect outbreak.

Here in Utah, at the time of the transcontinental railroad, migratory locusts periodically descended on the homesteads of Mormon settlers, laying up to 1 billion eggs per acre. These ravenous swarms devoured crops, vegetation, even laundry hung out to dry. Around the Great Salt Lake, drowned pickled grasshoppers would wash ahore in vast drifts. Native peoples gathered these salty, sun-dried hoppers for food, a rich source of protein and fat.

Why are we no longer plagued by locust swarms? It appears that the Rocky Mountain locust, went extinct at the turn of the 20th century. Entomologist Jeffrey Lockwood reports that the DNA of specimens preserved in the ice of glaciers in the Wind River Range are like no other grasshopper alive today. The cause of the locust’s abrupt extinction may never be known with certainty, but Lockwood believes that these outbreaks originated in the mountain meadows of the northern Rockies. By the 1880s, these public lands were packed with cattle and sheep, far more than the land could sustain. In a few short years, livestock stripped bare the very core habitats needed by the Rocky Mountain locust, leading to its abrupt extinction and the end of locust swarms in North America.

This is Linda Kervin for Bridgerland Audubon Society.

Credits:

Photo: Courtesy & Copyright © 2008 Lynette Schimming (As found on www.bugguide.net)
Text: Jim Cane, Bridgerland Audubon Society

Additional Reading:

Locust: The Devastating Rise and Mysterious Disappearance of the Insect that Shaped the American Frontier, Jeffrey Lockwood, Basic Books, 2004,ISBN:9780738208947, https://www.amazon.com/Locust-Devastating-Mysterious-Disappearance-American/dp/0465041671 See also: https://www.jeffreylockwoodauthor.com/locust

First and annual report of the United States Entomological commission for the year 1877 relating to the Rocky Mountain locust and the best methods of preventing its injuries and of guarding against its invasions Digitized by Google Books from Harvard University

https://en.wikipedia.org/wiki/Locust

Pestiferous Ironclads: The Grasshopper Problem in Pioneer Utah, Davis Bitton and Linda P Wilcox, Utah Historical Quarterly, 46 #4 as found on “Utah History to Go” https://historytogo.utah.gov/utah_chapters/pioneers_and_cowboys/pestiferousironclads.html