Spreading your wings beyond butterfly collecting

 kw: book reviews, nonfiction, science, natural history, insect collecting, moth collecting

I got my start as a collector collecting butterflies, using a net made from discarded a lace curtain. Later I collected all kinds of things, such as stamps, shells, minerals, and fossils. These days I collect primarily photos; they take up less space and they aren't heavy (like the two tons of low-to-medium quality agate I discarded many years ago). If I wanted to take on another collecting hobby, Tim Blackburn's new book would motivate me in the direction of collecting moths.

His book is The Jewel Box: How Moths Illuminate Nature's Hidden Rules. Dr. Blackburn is a professor of Invasion Biology in London. He bought a lighted moth trap online at the beginning of the Covid lockdown, and found that moth-ing fit in well with his profession and proclivity. He discusses the interconnectedness of ecology and the many interactions that drive the evolution of moths, and by extension, all animals and the plants they eat.

As a student of Invasion Biology, he begins his book with that poster child of invasiveness, the Gypsy Moth, Lymantria dispar. This male moth has the characteristic enormous antennae, with which the male detects very tiny amounts of the pheromone emitted by the female. This image is similar to one in the book, but more clear and in color (only black-and-white photos adorn the book's pages).

Gypsy moths are pan-Mediterranean and Asian originally, and their presence in various part of the British Isles has ebbed and flowed with the vagaries of time. Their introduction into the United States by Leopold Trouvelot in 1868 at first didn't make much impression. His intention was silk production, but that didn't work out well. Some moths escaped (As Malcolm says in Jurassic Park, "Life finds a way."). For a decade they didn't spread far, but then their population exploded. Their caterpillars erupted on trees in such numbers that a tree could be stripped of leaves in a few days, and major portions of some orchards were destroyed. The species name dispar means "destroyer".

Another moth called The Uncertain, Hoplodrina octogenaria, is discussed as one of a group of species that are hard to tell apart. The photo in the book shows three small moths that look alike in markings, though they have slightly different base tones. The Uncertain can only be identified "for certain" by dissecting its sex organs. Only particular differences in this bit of anatomy keep the look-alike moths from interbreeding!

At rest, like this specimen, their size is about 20mm (3/4 inch). In flight their wingspan is about 38mm (<1.5 inch), so they are medium-sized…for a moth. Size is a peculiar matter with moths. A number of taxonomic families consisting primarily of species measuring less than 20mm wingspan are called "micromoths" or "microlepidoptera", yet each family includes some members that are larger, perhaps quite a bit larger. Furthermore, some families consisting primarily of "macromoths" include micro-sized species, including the Noctuidae, to which The Uncertain belongs. So it is a macromoth, but some of its sister species are only 1/3 its size.

This unnamed moth is a typical micromoth. The wings are about 8mm long, so its wingspan is probably 16-17mm.

The smallest moths include those having caterpillars that are "leaf miners": the larva lives between the surfaces of a leaf, eating the flesh between. A caterpillar that can fit inside an oak leaf will develop into a very small moth. Following the rule that small things outnumber big things, there may be several thousand of the big, day-flying moths we call "butterflies", and tens of thousands of similarly-sized night-flying moths, but there are hundreds of thousands of smaller moths known, and it is likely that the total number of moth species is several million. We just don't now yet. Dr. Blackburn surmises that moth species may outnumber beetle species.

Each chapter focuses on a few related matters, such as predator-prey dynamics, migration and other issues of movement, or strategies of food sources. Again and again he reminds us that ecology is a whole, but a very dynamic whole. The year-to-year changes in environmental conditions, including more or less rainfall or higher or lower average temperature (which affect food sources and species vitality), or in-migration of a new species or local extinction of a formerly common species (which may be either a predator on or the prey of certain moths): all affect the continuing vitality of every species. Some become more abundant and some less, and there are often cycles of abundance.

Gradually one realizes that a matter introduced at the beginning of the book is the key to the title. This picture shows a lighted moth trap. This is the jewel box. Every morning it contains many new jewels.

The author reports frequently collecting 200-300 specimens from the trap when used in his London home (a terrace apartment), and about 50% more when used at his parents' place in the Devon countryside.

This emphasizes that moth trapping is a time-consuming hobby. If you are trapping to collect and identify and store the insects you trap, it takes a significant chunk of your day, every day! If the few hundred moths caught belong to 50, or 60 or more species (80 is a common number in a London trap), just the sorting and identifying takes much time, at least when one is learning to recognize the species. I reckon the process gets quicker with experience. Collection trays then multiply…

A similar device for collecting moths, and other night-flying insects, is a sheet with a light shining on it. It is used for an hour or two rather than overnight. A sheet trap is particularly useful if one doesn't plan to collect (and kill) the moths, but just to census them from photographs. The dozen largest moths in this picture can probably be identified right off. A series of closeup photos should allow identification of most of them, at least to genus level.

I have used this method. In my experience, if a sheet trap is used in a backyard, one will gather mostly moths. If it is done in a forested area, a lot of beetles will join the moths, and frequently, a number of flies and small wasps also.

The book is full of ecological information, on which I have barely touched. The author's enthusiasm for his new pastime shines through every page. This is a very enjoyable book, and it may introduce some folks to a rewarding hobby. Natural History Societies in many U.S. states and in many countries have ongoing data collection efforts to which citizen scientists can contribute. The Moths Matter site is one place to start.

I have one issue I must mention. The term "moth-ers" is used in the Acknowledgements, referring to moth collectors and enthusiasts. Throughout the book the hyphen is not used, and confusion with the word for "female parent" is evident. The hyphen is needed! It must never be dropped. Although we have the term "birder" for bird watchers and bird enthusiasts, there is no competing meaning for this word, so no hyphen is needed for it. But please, moth people, embrace that you are moth-ers. Thank you.