Bugs

The living creatures that we have categorized as “insects” outnumber all other species put together by…well, a lot.  Frankly, if I were to give you a number, you would pretty much know that I or whoever I had gotten the number from would be mostly guessing about it.  There are (as far as we currently know) around 900,000 distinct species, comprising 70% of all known species (of anything) on Earth — and entomologists estimate that we have only identified about 20% of the insect species that may exist.  Insects are found virtually everywhere, adapted to a staggering variety of climates, habitats, and ecosystems.  Many species are remarkable for the intricate symbiotic relationships they have formed with other species: plants, animals, other insects.  And, of course, humans.

So naturally, I have some questions about bugs.

First question: If there are over 8000 insect species that are known to be edible by humans, why don’t we eat more bugs?

Around the world and throughout the centuries, hundreds of cultures have used thousands of insect species directly as food.  In modern times, at least several of these thousands play an economically important role in direct food production.

Photo: Mopane worm (Gonimbrasia belina) on a mopane tree, by JackyR courtesy of Wikimedia Commons

Take, for example, the mopanie or mopane worm. The mopanie is the larva (caterpillar) of the emperor moth (Gonimbrasia belina), a member of the surprisingly important genus Saturniidae, which we’ll see more of later.  The common name is the result of the larva’s habit of feeding mainly on the mopane tree (Colophospermum mopane).  The tree and the moth are native to southern Africa, and are harvested on the order of hundreds of tons per year as an important source of protein for the region, especially Zimbabwe, Zambia, Botswana, and South Africa.

Photo: The common house cricket (Acheta domesticus), by Petr Gebelt courtesy of Wikimedia Commons

The common house cricket (Acheta domesticus), native to China but now naturalized to North America and other parts of the world, has for decades in the United States been raised as food for exotic pets.  Now, food-grade cricket farms are becoming the next big thing in cottage or hobby farming.  Not without good reason.  Crickets have a feed-to-food ratio of about 1 to 1, as compared to about 6 to 1 for beef cattle, or 1.5 to 1 for poultry.  In addition, crickets do not produce greenhouse gases, and are easy to breed and raise by just about anyone, with little initial capital investment.  The supply chain currently consists of small cricket farmers selling their stock to businesses specializing in processing the crickets, usually into powder (aka “cricket flour”), which is in turn sold to food producers.  It’s a growing industry that I personally hope will stick around and diversify to include other insect species.

Like, for example, mealworms.  Mealworms are the larvae of the mealworm beetle (Tenebrio molitor), and they are also making inroads into human cuisine.  Previously regarded as a pest, since they invade and feed on stored grains, mealworms have transitioned into pet food, and now human food, where they have been a popular food source in Southeast Asia for at least a few decades.

Photo: Mealworm (Tenebrio molitor), by Rasbak courtesy of Wikimedia commons

In for a penny, in for a pound, that’s what I say.  Once you open the door to insects as food, the world becomes your oyster.  Mixed metaphor, yeah, I know.  But you know what I mean.  If you’re interested in exploring the topic of raising insects for food, I found the little book below to be a handy introduction.  It’s short and doesn’t go into a ton of detail, and doesn’t address the commercial side of farming insects at all. But it gives a good overview, and would definitely allow you to get started raising crickets and mealworms.

(paid link)

A good starting point for the exploration of the topic of bug-eating around the world is the reprint of an article found in the journal Crop Protection, Volume 11 (Issue 5), pp 395-399, titled “Insects as Human Food” by Gene DeFoliart.  A free excerpt can be found here: Insects as Human Food.

Next question:  Are silkworms the only insects that produce usable silk fiber?

No.  Next question.

Just kidding.

The insect that we know as the “silkworm” is the larva (caterpillar) of several species of moth in the genus Saturniidae.  The best known of these is the domesticated silkmoth, Bombyx mori.

Photo: Bombyx mori larvae on mulberry leaves, by Lilly M courtesy of Wikimedia Commons

This silkworm is native to China and the practice of breeding the moth to produce silk fiber (sericulture) is at least 5000 years old, and may be significantly older.  Bombyx mori is now cultivated worldwide, though the top producers by far are China and India.  Silk fiber is known for its durability and natural shine, both of which have made it a popular textile fiber for in Asia for millennia, and for centuries in the West since its introduction to Europe in around the eleventh century. Famously, the favored food of the silkworm is the white mulberry (Morus alba), which is why this silk is also known as mulberry silk.  So, if you want to cultivate silkworms, you also have to know how to cultivate white mulberry. Can’t have one without the other.

Photo credits: (Left) Silk cocoons by Katpatuka, (Right) Raw silk by Armin Kubelbeck, Wikimedia Commons

The silkworm is one of only two cultivated silk-producing moths.  The other is the Ailanthus or eri silk moth (Samia cynthia ricini), native to India, China, Japan, and now naturalized to parts of Thailand.  The favored food of the eri moth is the castor plant and the Ailanthus tree (tree of heaven).

Photo credit: Ailanthus silkmoth (Samia cynthia ricini), by Hectonichus courtesy of Wikimedia Commons

The cocoons of its larvae are harvested to produce eri silk, which is more durable than that of the Bombyx mori, but has a more woolly texture.   Some traditions produce eri silk without killing the caterpillar, by allowing the larva to first leave the cocoon and then unreeling the silk. In northeast India, where the tradition of eri silk originated, the cocoons were harvested mainly for the protein-rich caterpillars, and the silk was then used to weave the traditional chaddar (wrap).

In addition to cultivated silk, there is also wild silk.  For example, Tussar silk (also known as Kosa silk) and Muga silk are produced by several species in the genus Antheraea within the Saturniidae family.  Native to India, the moths’ cocoons are harvested from wild groves of trees that host the insects. Tussar and Muga silk is widely used in India to make the beautiful traditional sarees and chaddars.

A brief but informative overview of the different types of silk and the silk industry in India can be found on the Central Silk Board of India’s website here.

Many other insect species outside of Saturniidae also produce silk: spiders, crickets, other moths — to name a few.  Some of these are being investigated as possible sources of commercial silk fiber, and it will be interesting to see where this investigation takes us in the future: Spider silk stockings?  Raspy cricket surgical sutures? Who knows?

Next question: What the heck?

It’s inevitable that whenever you’re exploring human invention and the natural world, you’re frequently going to be struck with the question: How did anybody ever think of that?

For example, scale insects.

Scale insects comprise a group of roughly 8000 species of small insects in the superfamily Coccoidea, that are usually plant parasites.  One of their dominant common characteristics is that the females produce a protective waxy coating that makes them looks as if they have scales (hence, the common name).   I can understand how someone would look at that wax and think that it might be useful — and, in fact, it is.  For example, Chinese wax, which is used to manufacture polishes, candles, and other items, is a product of certain species of scale insects native to China and Japan.

Similarly, the lac insect (Kerria lacca) native to India and Asia, produces a resinous protective coating called lac, which is the only known resin of animal origin.  Lac is refined to produce shellac, a type of varnish that has many uses, including as a wood finish and a fruit wax.  This characteristic has made the lac insect the most commercially important of the scale insects, with several thousand tons of shellac produced annually.  Again, I can understand how a person (especially given the long history of use of plant resin) could look at bug resin and think “I can use this for something.”

Photo: Kerria lacca resin on a tree branch, by Jeffry W. Lotz courtesy of Wikimedia Commons

But, how could someone look at a tiny bug living on the roots of herbs, and think to himself, “Hmm, I bet if I squash this and mix it with aluminum and calcium salts, I’ll get a nice strong red dye.”  But that’s in fact what happened (well, something like it, anyway).  There is a group within the scale insects known as the cochineals, and the bodies of these species contain generally high amounts of carminic acid, which is used to make the red dye known as carmine.

The Polish cochineal (Porphyrophora polonica), native to Central Europe and parasitic to primarily the herb knawel (Scleranthus annuus), was for several centuries and through the Middle Ages of great economic importance as a source of red dye.  After the colonization of the Americas, it was largely replaced by the Mexican cochineal (Dactylopius coccus) as the source of carmine.  And yes, there are cochineal farmers still around in Central America today, raising the insects to produce the dye, which is still used as a food coloring and in cosmetics.  If you’re thinking about becoming a cochineal farmer, though, keep in mind that the insect is parasitic to the Opuntia genus (the prickly pear cacti), so you have to live where those grow.  Just FYI.

Photo: Cultivated cochineal nests on Opuntia, by Oscar Carrizosa courtesy of Wikimedia Commons

And on that note, I’ll wrap up this discussion of the fascinating and ever-changing relationship of humans and bugs.  With this one final thought: of all the bizarre symbiotic relationships that exist between plants and insects, and humans in the mix, the one between the fig wasp and the fig tree strikes me as one of the more awe-inspiring.  The fig wasp and fruit-producing fig tree are completely dependent on each other for the completion of their reproductive cycles.  While humans have managed to breed certain varieties of figs that can be propagated without the wasp, the Smyrna fig remains firmly dependent on the fig wasp.  So, next time you bite into a tasty Smyrna fig, say thanks to the tiny wasp that made it possible.

Here’s a link to a well-done video that talks about the history, nutritional value, and cultivation of fig varieties, including the relationship with the fig wasp.

The Nutritional Value of Fig Wasps

P.S. What about bees?

Yeah, bees are an awesomely big and important topic.  The relationship between bees and humans is very long and very intense.  So long, in fact, that there is at least one cave painting, dating to roughly 6000-8000 B.C., that depicts a human harvesting a beehive (it’s located in Cuevas de la Arana — Spider Caves — in Bicorp, Spain).  We look to bees not only for the important products they make (honey, beeswax, propolis, and royal jelly), but for their even more important role as plant pollinators.  Without bees, many important crops could not be cultivated (or exist at all, in some cases).  Bees will appear many times in this blog, including the next entry, which will be a discussion of the topic of “Wax.”

For now, I will recommend this beautiful and practical book about modern beekeeping and the history of the human relationship with the European honeybee.  It’s a fascinating read, even if you’re not into beekeeping — and if you are, it’s got a lot of great information to get you started.

(paid link)

Additional References:

(1) Encyclopedia of Insects, by Vincent H. Resh (Ed.) and Ring T. Carde (Ed.).  This would seem like a crazy undertaking to try to catalog all 900,000 species of insect, but if you’re really into learning about the insect world, this is a great reference that highlights some relevant and interesting patterns.  And at almost 1200 pages, it’s got great detail, too.

(paid link)

(2) I have not read the whole book, but I can tell you that it’s dense and contains more information than the average person would ever want to know about commercially producing insects as human food.  If you’re not the average person, this might be a good choice for you.  Just the fact that there’s a textbook on the subject is pretty cool all by itself.

(paid link)

(2) Since sericulture (silk cultivation)is mostly practiced in Asia, most of the books out there are by and for agriculturalists in Asia.  Nevertheless, there was a time when the silk industry was thriving in the United States — and who knows, maybe it could be again.  For a short history of silk production in the U.S. see this article.

This is a very robust and detailed manual on sericulture.

(paid link)

And here’s a lighter version, lacking the depth and detail, but still a useful overview of the practice.

(paid link)