Insects — worthy of more respect

 kw: book reviews, nonfiction, science, insects, ecology, entomology

To a first approximation, the average animal on Earth seems to be an ant of medium size, a little smaller than a rice grain. According to Steve Nicholls, as he writes in Alien Worlds: How Insects Conquered the Earth & Why Their Fate Will Determine Our Future, ants make up one-third of the total biomass of all insects (p. 439). The total biomass of insects, around one billion tons, equals the total mass of all humans plus all domestic animals.

As these leafcutter ants illustrate, insects were farming millions of years before humans began doing so. Leafcutter ants chew up leaves to grow nutritious fungi. Other insects carry out similar kinds of agriculture. 

Insects, again illustrated by ants, also took up ranching long, long ago. As we see here, these ants guard and "pasture" aphids and drink the honeydew they provide (others care for mealybugs).

Alien Worlds is a heavy book; the paper is supercalendered, meaning it is loaded with clay to make photographs look better. It is also more dense. This 500-page book, which doesn't look much larger than a typical novel, weighs almost three pounds; the novel would weigh a pound and a half. The quality of the images makes it all worth it.

About a third of the "real estate" of the pages consists of eye-popping photos. Mr. Nicholls is a documentarist who has traveled the world preparing programs, and he has a wealth of material on which to rely. I'll resist the temptation to scan a bunch of the pictures, and just tantalize you with one, this Hummingbird Clearwing moth, Hemaris thysbe, feeding. It is a type of hawk moth, and is about this size. This image is cropped from one page of a two-page spread showing two of these moths feeding.

The obligatory historical review in the first few chapters presents the place of insects in the arthropod phylum, a basic history of their development, and discusses some of the reasons that they became the most successful class of animals (basically: extreme flexibility of foods and conditions they can endure).

Those who are familiar with biological classification can skip a few paragraphs to the arrow below. Biological entities are named with two Latin or Latinized words, such as Tyrannosaurus rex or Homo sapiens, and the words are (or ought to be) italicized whenever possible. The first word of the scientific name, the capitalized word, is the Genus, and the second, uncapitalized word is the Species. Homo is a genus of primates that presently includes only the species sapiens, but in the past there were other species such as neanderthalensis and ergaster. A scientific name, the genus and species, must be unique, to avoid confusion.

The plural of genus is genera and the plural of species is species (no inflection); they are Latin plurals. The hierarchy of major groupings is, from top down:

• Kingdom – There are 5 or 6; here we are interested in Animalia, the kingdom of animals.
• Phylum – There are about 40 phyla of animals. Most of the creatures people call "animals" are in the phylum Vertebrata, animals with backbones. Earthworms are in the phylum Annelida. Insects and related creatures are in the phylum Arthropoda.
• Class – In the Arthropoda there are five classes. More on that below. Insect species make up about 70% of the total.
• Order – The class Insecta includes 29 orders. For example, Lepidoptera includes the moths and butterflies, and Hymenoptera includes wasps, bees, and ants.
• Family – Too many to count, and the number changes almost weekly as naturalists find new species and taxonomists (systematists) regroup existing ones.
• Genus 
• Species

The phylum Arthropoda has these groups:

These are not exactly the classes. Chelicerata, Crustacea and Insecta are classes. The myriapods are made up of two primary classes, Diplopoda (millipedes) and Chilopoda (centipedes), plus a few very minor but very distinct classes. The extinct class Trilobitomorpha  rounds out the bunch. All the living classes include members that live on land; the little "pillbugs" or wood lice, for example are crustaceans, related more to crabs than to insects.

→OK. The author, having brought the evolution of insects and their arthropod kin up to date, dwells for a chapter on the co-development of insects (and some other arthropods such as ants) and flowers. The rest of the book works its way up the ladder of social organization, finishing with bees, wasps and termites. A major aim of the author is to show how insects are integrated into every aspect of life, and how much of our "civilized" lifestyle depends on them. A few tidbits:

• Do you like almonds, a trendy superfood? Honeybees pollinate them, and the almond groves of central California need to have millions of beehives trucked in to provide a sufficient number of bees. Although other species of bee are good pollinators—sometimes working five times as hard—only honeybees exist in numbers sufficient to pollinate the almond crop. About half our plant foods require pollination by bees.
• Dung beetles and related beetles and other insects keep us from being awash in cow poop.
• Burying beetles (sexton beetles) and other members of the "cleanup squad" dispose of the bodies of little animals that die "out there", and the remains of larger animals after vultures and coyotes have picked their skeletons almost clean.
• In many cultures insects or their larvae are a necessary food item.

Another couple of interesting items: Firstly, tool use. Some insects use pebbles or bits of twig, though these behavior probably evolved and don't seem to be learned as cultural attainments the way tools are used and learned by various birds and mammals. Secondly, language. I think most of us know about "waggle dancing", a communication method among bees, to indicate the direction and distance to a productive patch of flowers. Many insects also communicate by sound, although none have a humanlike vocal apparatus. Most insect sounds are stridulation, the rubbing of legs or wings against other body parts, which makes sounds that are often amplified by resonance. Apparently, bess beetles in particular use different sounds for different purposes. These beetles are 1-1.5 inch (25-40 mm) in size, usually shiny and black, but they are seldom seen because they tunnel in rotting wood. One North American species, Odontotaenius disjunctus, makes seven distinct sounds, combined into as many as 13 utterances for different contexts (such as "food here" or "danger"). The beginnings of language? The author doesn't mention if these "words" are learned, but does tell us that each species has its own dialect.

Many have noticed that taking a drive in the countryside can now be done without the need to clean your car's windshield every 50 miles or so. When I was a child this was not so. This is often decried as an indicator that insects are in steep decline. They probably are, but I wonder to what extent we killed off all the low-flying ones, and if cars were 20 feet taller, maybe there are still plenty of critters in fight to run into. However, cars and their windshields aren't much of a culprit. Habitat destruction and overuse of pesticides take a much greater toll. I find it quite distressing to see farm after farm and orchard after orchard being sold to developers, who build housing developments or even mini-towns complete with apartments and retail outlets and office plazas. In my view, turning agricultural land into hardscape is criminal. Mr. Nicholls probably believes this also, though he doesn't state it the same way.

Besides the visual appeal of hundreds of photos, the discussions and explanations are enjoyable and impel one right along through this briefest of summaries of the vast subject of insect lore.

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If you don't care about errata, you can stop already. I am a compulsive proofreader, so I noticed a few things, a few more than I find normal:

First and foremost, discussing insect sizes, which range from 0.129 mm for a species of fairyfly (a tiny wasp) to 110 mm for the largest species of goliath beetle (stick insects can get 2-3 times this long, but they weigh much less), he states in page 45, "The size range of insects covers only three orders of magnitude, small compared to fish, for example, whose size range covers eight orders of magnitude." This is just nuts. Eight orders of magnitude is a range of 100 million to one. If the smallest fish is 1 mm in size (it's larger than that), then is the largest fish 100 km in length? He seems to have used the lengths of insects, but the weights of fishes. Let's investigate.

• Fairyfly length and weight: 0.129 mm and 25 micrograms (0.000025 g).
• Goliath beetle length and weight: 110 mm and 100 g (larva) or 60 g (adult).
• Dwarf goby length and weight: 7.9 mm and 60 g.
• Whale shark length and weight: 18 m and 20,000 kg (18,000 mm and 20 million g)
• Orders of magnitude for these insects: log(110/0.129) = 2.93, which is close to 3 for length; log(100/0.000025) = 6.6, so between 6 and 7 orders of magnitude for weight.
• Orders of magnitude for fishes: log(18,000/7.9) = 3.4, or something over 3 for length; log(20,000,000/60) = 5.5, so between 5 and 6 orders of magnitude for weight.

All this indicates that the extrema for length are in the range of three orders of magnitude for both fish and insects, and the extrema for weight are in the range of six orders of magnitude for both, with the insects having a greater range of weights! I have no idea where "eight" came from. This is worse than a simple cross-category error.

Lesser items that ought to have been caught by a copy editor:

• p125: The word for a gripping tool is "vise". The word "vice" was used, an error I see frequently, but "vice" is a sinful tendency such as over-drinking.
• pp200 and 305: At the beginning of a sentence, the starting letter was not capitalized.
• pp211 and 432: The footnote is a copy of the one on the prior page.
• p422-3: The phrase in parentheses "(soccer against)" should be "(soccer again)", as he'd made a comment about soccer a few sentences earlier.