From the University of Wyoming, I wish to thank Professors Greg K. Brown, Ron Canterna, Mark Lyford, and Terry Roark for providing knowledge, advice, books, information, comments, and encouragement. I also wish to thank the UW Berry Biodiversity Conservation Center, directed by Carlos Martinez del Rio, which contributed to the costs of the color plates. I’m very grateful to Dr. Danita Brandt (Invertebrate Paleontology, Department of Geological Sciences, Michigan State University) for her thoughtful technical and editorial notes on chapter 2 and for graciously allowing me to outline her research in that chapter. Dr. Conrad Labandeira (Smithsonian Institution) and Dr. Michael Engel (University of Kansas) both thoughtfully read chapter 5 and made many helpful suggestions. Dr. Douglas H. Erwin (Smithsonian Institution) graciously read chapter 6, which relies heavily on his pioneering research on that subject. Brandon Drake carefully proofread chapter 8 and contributed to my more accurate depictions of dinosaurs.
I wish to thank the following people for generously contributing photographs of living insects and other arthropods: Jennifer Donovan-Stump (Trinity School, New York, New York), Dr. Janice Edgerly-Rooks (Santa Clara University, California), Andy Kulikowski (Casper, Wyoming), Kevin Murphy (Irish Wildlife Photography, Westport, Ireland), Kenji Nishida (Monterverde, Costa Rica), Angela Ochsner (Torrington, Wyoming), David E. Rees (Timberline Aquatics, Fort Collins, Colorado), and Dr. Barbara Thorne (University of Maryland, College Park). Images of insects in amber were kindly contributed by Dr. Vincent Perrichot (Université de Rennes, France) and Dr. George Poinar Jr. (Corvallis, Oregon). The following people assisted with obtaining permission to publish images of insect fossils: Dr. Olivier Bethoux and Aurélie Roux (Muséum national d’Histoire naturelle, Paris, France) and Dr. Brian Farrell, Dr. Philip Perkins, Amie Jones, and Catherine Weisel (Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts). Marlene L. Carstens (University of Wyoming Photo Services) assisted with the production of digital images from black and white negatives. Helmuth Aguirre, my graduate assistant, kindly helped with the arrangement of images into plates.
I especially wish to thank Professor Paul E. Hanson at the University of Costa Rica for years of friendship and kind assistance with local arrangements for travel to La Selva Biological Research Station and San Ramon Biological Reserve, which inspired parts of this book. Paul, you really helped me “get my feet wet” in the tropics, for which I am very appreciative.
I owe the greatest debt of gratitude to my editor at the University of Chicago Press, Christopher Chung, for seeing merit in my writing and patiently working with me, providing thoughtful and detailed comments, and helping me to reshape my bulky manuscript into a sleeker and immensely more readable book. All my readers will benefit from Christopher’s vision and hard work. Mary Gehl copyedited the final manuscript and made many insightful suggestions and corrections.
Stephen King I thank for his published thoughts about time travel and the craft of writing. Jane Auel I thank for her inspirational lecture at the University of Wyoming about her history as a writer. Many thoughtful people provided inspiration, helpful suggestions, information, and corrections; any errors that remain are my own.
I hope this book inspires the next generation of bug hunters with the same passion that my first butterfly net infused into me.
Finally, I wish to thank my wife, Marilyn, and my sons, Matthew and Michael. It’s not easy living with an aging, distracted, and absent-minded entomology professor. Sometimes it’s been hard to pay attention at the dinner table when I was trying to work out the history of the earth in the back of my mind. Your love and support through this process has been crucial, and I am profoundly grateful.
About the Author
Scott R. Shaw was born in Detroit, Michigan, in 1955. He started collecting insects at the age of 4. From 1973 to 1978 he attended Michigan State University where he studied astrophysics and entomology. He attended the University of Maryland from 1979 to 1984, where he obtained MS and PhD degrees in entomology. From 1984 to 1989, he worked at Harvard University in the Museum of Comparative Zoology. Since 1989, he has lived in Laramie, Wyoming, where he is professor of entomology at the University of Wyoming and Insect Museum curator. Professor Shaw has discovered and named 163 new insect species (mostly wasps) from 29 different countries. Fifteen insect species have been named after him by other scientists. He has published more than 114 scientific articles about insect classification and evolution. He has named insect genera (Betelgeuse, Rigel, Orionis) after stars in the sky and stars of late night television (Marshiella lettermani, a wasp named for David Letterman). His published suggestion for a Wyoming state insect, Sheridan’s green hairstreak butterfly, was adopted by the Wyoming legislature and the governor in 2009. He has extensively studied insects in Costa Rica and Ecuador. This is his first book.
Notes
CHAPTER ONE
1. Many people are surprised to learn how much we still do not know about life on our own planet. We don’t even know how many species we share the world with. Estimates range from seven million to a hundred million, and most biologists would agree that the vast majority of unknown species are insects living in the canopies of tropical forests.
2. E. O. Wilson, 1990. “First word,” Omni, September, 6, 1990, Academic Search Premier, EBSCOhost (accessed November 19, 2013).
3. David M. Raup, Extinction: Bad Genes or Bad Luck? (New York: W. W. Norton, 1991), 14.
CHAPTER THREE
1. However, expect them to live a long time. My colleague Nina Zitani’s pet millipede lived for nearly twelve years.
2. The latest molecular studies of fungi suggest that the major lineages of fungal diversity evolved in tandem with the diversification of early vascular plants and terrestrial ecosystems. Fungal diversification certainly contributed to the evolution of microbial soils suitable for the colonization of land plants, and fungi also contributed to the diets of scavenging arthropods such as millipedes and symphylans. You can read more about fungal evolution in Robert Lücking, Sabine Huhndorf, Donald H. Pfister, Eimy Rivas Plata, and H. Thorsten Lumbsch et al., “Fungi Evolved Right on Track,” Mycologia 101 (2009): 810–22.
CHAPTER FOUR
1. I use the term “stroll” only artistically here. Recent research on the 360-million-year-old amphibian, Ichthyostega, suggests that it just inched along by bending and straightening its back. The earliest amphibians probably dragged their hind legs and tail.
2. According to my colleague, engineering professor John McInroy, there is a fundamental reason to use six legs. With six legs it is possible to translate and rotate in all three directions. Also, six-legged creatures can resist forces and torques in all directions. The stability of six legs is well known in the field of robotics. For more on walking robots, see Jean-Pierre Merlet, Parallel Robots (Dordrecht: Springer, 2005).
3. Perhaps I should point out that moving their legs three at a time is the way insects walk or run on a flat surface. Insects, because of their very small size, are also able to walk on vertical and even inverted surfaces. Recent research by S. N. Gorb indicates that they walk a bit more carefully on inverted surfaces. A fly on the ceiling moves slowly and carefully, leaving four legs planted and repositioning only two legs at a time. Upside-down walking on inverted surfaces is possible because insects are so small that the forces of surface tension and cohesion are proportionally greater. Attachment to both smooth and rough surfaces is improved by a variety of microscopic adaptations at the tip of the insect foot, including claws, hairy pads, and adhesive secretions. These characteristics were probably not present in the very earliest terrestrial hexapods, but were developed and refined in the lineages of flying insects over hundreds of millions of years. See S. N. Gorb, “Uncovering Insect Stickiness: Structure and Properties of Hairy Attachment Devices,” American Entomologist 51 (2005): 31–35.
4. Although Rhyniella praecursor is the oldest undisputed hexapod, most entomologists do not consider the springtails to be true insects. They have ver
y distinctive and unusual retracted mouthparts and appear to be a lineage of hexapods that diverged early from the line leading to most modern insects. However, older entomologists often called any six-legged arthropod, including springtails, an insect.
5. Until fairly recently, the archeognathans were combined with the silverfish and firebrats into a larger order called Thysanura, a name that is now being abandoned but that persists in some field guides and older literature. The extinct order Monura was described to include similar species that had only one bristlelike tail. Recent entomologists treat the monurans as members of the order Archaeognatha.
CHAPTER FIVE
1. This is an example of what ecologists call lekking behavior.
2. I’m taking artistic liberty with the mayfly story. While we are fairly certain that the mayflies, or at least the stem group of mayfly-like insects, first evolved in the Carboniferous years, we do not know for sure exactly when this line of insects first evolved freshwater, aquatic immature stages. They may not have done so until the Permian or even the Triassic years. But I’m guessing that they did go aquatic during the Carboniferous because of the age’s abundant wetlands and the resource advantages of moving first into the freshwater niches. If freshwater fish existed then, it seems reasonable to assume there must have been aquatic insect naiads for them to consume.
3. Lepidosaurian reptiles were gliders during the Triassic period, with forms similar to today’s Southeast Asian Draco. They may have been some of the earliest vertebrates to pursue and feed on winged insects in the air.
4. Cordaites plants had strap-shaped, broad-leaved foliage, as well as cones, and are considered to be closely related to the earliest conifers.
5. One diverse group of plant-decomposing arthropods was present in the Late Carboniferous: the oribatid mites. Primitive wingless insects and millipedes were also responsible for some of the decomposition.
6. While the beetles (order Coleoptera) have been known from Permian fossils for quite some time, only recently has evidence for Carboniferous beetles been discovered, by Béthoux (O. Béthoux, “The Earliest Beetle Identified,” Journal of Paleontology 83 [2009]: 931–37). While the first beetles, as well as some other kinds of insects with complex metamorphosis, may have first originated during the Late Carboniferous, they were still rare and not diverse, and consequently did not yet have a profound ecological impact on forests. My discussion of beetles will await the next chapter, on the Permian period, when beetle species diversified and became common.
7. I do not mean to imply that coal production ceased after the Carboniferous, but only that from the period onward, the diversity of decomposing organisms, and competition for plant materials as food, increased. There are some significant coal deposits from much more recent times, such as the Paleocene open-pit mines near Gillette, Wyoming.
8. Along with the jumping bristletails, the silverfish were formerly placed in a larger order called Thysanura, a name that is still to be found in older literature. They are separated now because of their different mandible forms, as discussed in the last chapter.
9. Scientists have recently discovered that modern wingless insects, including silverfish and even worker ants, can manage a kind of gliding flight while falling from trees. Their bodies seem to function as an airfoil. During free fall they can turn and glide back to the tree trunk, and so avoid falling all the way to the ground.
10. Ancient paranotal lobes share a similar venation pattern with modern fully formed wings, which implies that wings evolved from appendages resembling the paranotal lobes.
11. This is clear because fossil paleodictyopteroid nymphs from Mason Creek are associated with Macroneuropteris foliage and have plant spores in their guts (Conrad Labandeira, personal communication).
12. We don’t know the exact date of the very earliest flying insect, but we do know that winged insects were abundant and diverse by the Late Carboniferous, 320 million years ago. They may have maintained sole ownership of the airways for 100 to 150 million years or more before vertebrates finally took to the air.
13. Evidence suggests that the Paleodictyoptera were not the only plant-feeding insects that evolved during the Carboniferous. Other feeding styles, from fossil plant damage and coprolite evidence, include boring into plant tissues and stems, preying on seed fern seeds, and feeding (hole-feeding, margin-feeding, and scratching the surface) on the external foliage of multiple Carboniferous plant species.
14. In addition to spores, coprolites preserve microscopic fragments of plant tissues and wood which are assignable to particular plant-host species. So the study of coprolites provides insight into the herbivore consumption patterns and food webs of ancient times.
15. We have limited knowledge of the Carboniferous plants’ chemical defenses. The common kinds of chemical defenses in modern plants, such as phenols, alkaloids, and tannins, degrade into by-products during fossilization, and cannot be recovered. However, fossils of some Carboniferous seed ferns contain resins, which preserve unique secondary chemical compounds that, according to Smithsonian paleontologist Conrad Labandeira, probably were used as insect-deterring compounds.
16. I’m making a bold assumption here. Fossil evidence as to where immature griffenflies lived is very rare. They might have been fully aquatic, like modern dragonflies, or they might have been terrestrial or semiaquatic in the humid forest undergrowth. We do know that the forests were filled with diverse potential predators, such as centipedes, spiders, scorpions, and amphibians. It seems to me that in order to grow as enormously large as an adult griffenfly, the developing young must have lived in a somewhat sheltered habitat. At least they would have avoided spiders, centipedes, and scorpions in the fresh water ponds, so developing there seems far more likely.
17. Because some insect paleontologists think that the Carboniferous roaches are considerably different from modern ones, they refer to these creatures as “Paleozoic roachoids” or “ovipositor-bearing cockroaches.” This terminology is cumbersome, so I’ve elected to use more familiar terms and simply call all of the ancient species “roaches” or “cockroaches.” Although they are unlike modern roaches in some important ways (for instance, they have a visible ovipositor), if we could travel back to the Carboniferous, we would readily recognize them as roaches and probably declare the place one huge roach-infested swamp.
CHAPTER SIX
1. Fans of movie trivia may recall that Clint Eastwood made his brief debut in this film as the heroic jet fighter pilot who fires the rocket that destroys the giant mutant spider.
2. This developing drama of the warm-bloods has one interesting side note. About this time some small insects of the now-extinct order Diaphanopterodea evolved long, slender mouthparts, and some of them resembled mosquitoes. This is the first instance of possible blood feeding by insects, perhaps not coincidentally at the same time that warm-bloodedness appeared. Maybe insects were going on the attack. I’m just speculating, but did ancient blood-sucking insects spread diseases among the herds of protomammals? Living mosquitoes are known to transmit more than two hundred kinds of blood-borne diseases, so it is certainly plausible that Permian blood-feeding insects, such as diaphanopteroids, might have transmitted fatal diseases among the herds of Tartarian protomammals.
3. Order diversity was greater then because the Permian was a combination of lingering Carboniferous lineages, in addition to numerous later lineages, that diversified at that time and had descendants that survived the extinction. These survivors formed the core of the modern insect fauna that thrives today.
4. As we discussed in chapter 2, trilobites originated and were most diverse during the Cambrian period. They become scarcer, relative to other marine groups, in Paleozoic-era sediments. Even so, I selected trilobites as my symbol of the entire era because they persisted across that time, but do not appear at all in Mesozoic or Cenozoic sediments. For the end of the Permian, fossils of brachiopods, bryozoans, and crinoids are better geological markers because they were more common t
hen. By the Late Paleozoic, trilobite species diversity was very low, so perhaps their extinction was inevitable.
5. Volcanic explosions across Permian Siberia spewed 1.5 million times as many airborne particles as the 1981 eruption of Mount Saint Helens.
6. Fossils of Permian grylloblattids still show wings, but by the Late Cretaceous period they were wingless.
7. Some authors treat the homopterans as part of the order Hemiptera (discussed in the next chapter), and divide them into three suborders: Sternorrhyn-cha, Auchenorrhncha, and Coleorrhyncha. This nomenclature is obviously a bit cumbersome, so I prefer to refer to these insects by their simpler and more familiar name: homopterans.
8. The oldest fossil insect larva and the oldest fossils of adults from several groups known to have complex metamorphosis are from the Permian period. There are some fossil plant galls from the Late Carboniferous, and since modern galls are mostly caused by insect larvae, some scientists, such as Smithsonian paleontologist Conrad Labandiera, have speculated that complex metamorphosis first developed late in the Carboniferous. The discovery of some putative holometabolous insects from the Late Carboniferous led Nel and colleagues to refer to complex metamorphosis as “a crucial innovation with delayed success” (A. Nel et al., “The Earliest Holometabolous Insect from the Carboniferous: A ‘Crucial’ Innovation with Delayed Success [Insecta: Protomeropina: Protomeropidae],” Annales de la Société Entomologique de France, n.s. 43 [2007]: 349). Most entomologists credit the drier climate (Permian aridity) for stimulating the diversification of holometabolous insects during the Permian period. Whatever the reason, we do know that they diversified explosively during the Late Permian, and that the groups with complex metamorphosis survived the end Permian well.
Planet of the Bugs: Evolution and the Rise of Insects Page 24
