Chenillar moments, including frass and lepidopterism

Two caterpillar notes, an old one and a very recent one.

First, from a Language Log posting of mine from 6/2/06:

As for the oak moths, we’ve been exceptionally afflicted by them this spring at Stanford — a rain of caterpillars [California Oakworms, Phryganidia californica], then masses of cocoons, and now clouds of moths.  Ick.  Susie Fork [posting on the Elkhorn Slough site], however, sounds pretty pro-moth.  Well, the Elkhorn Slough staff seem to value all the organisms they study.  But then they don’t have to live with clumps of cocoons disfiguring the pieces in the New Guinea Sculpture Garden, the way we do.


Then from a visit to Palo Alto’s Gamble Garden last week:


At the moment, the Western tussock caterpillars (Orgyia vetustaare everywhere. Here’s one just outside my house, catching the sun so that it appears to be a fierce incandescent creature:


(Tussock caterpillar photos by Kim Darnell.)

Linguistic notes 1. The tussock caterpillars are notably hairy, and indeed hairiness is the feature that gave us the name caterpillar (probably from a French dialect term meaning ‘hairy cat’). Meanwhile, in actual current French, the term is (la) chenille < Lat. canicula ‘little dog’ (note le chenillard ‘caterpillar tractor’), so called because of the hairiness of dogs; the same image leads to chenille as a fabric term, in both French and English (caterpillar tractors are so called because their mode of movement resembles the movement of caterpillars):

a tufted velvety cord or yarn, used for trimming furniture and making carpets and clothing (NOAD2)

A white chenille bedspread:


I find myself in want of an adjective meaning ‘of or relating to caterpillars’, and I reject both the neologisms caterpillaral and lepidopterolarval as being impossibly awkward. So I opt for chenillar (with the variant –ar of the derivational suffix –al that’s mostly used after stems ending in l).

[Added later: on reflection, I think it would by best to use the linking -i- with the suffix: chenilliar. Better rhythm.]

On with our chenillar explorations.

California oakworms / oak moths. From an information file (by park ranger Robert Badaracco, edited by Kathleen Jones) on the City of Palo Alto site:


Visitors to our preserves may hear faint clicking sounds as they walk the quiet trails of the preserves’ oak woodlands. A look at the surface of the trail would reveal thousands of tiny roundish pellets 1/16 inch in diameter. [These pellets are called frass, and they are a significant contributor to providing nitrogen to the soil under oak trees.] These are the droppings of the caterpillar or larvae of the California Oak Moth (Phryganidia californica) which feed upon the leaves of oaks. So voraciously do they feed that entire trees or forests are defoliated when these insects reach maximum populations. Fortunately, the oaks survive this onslaught by budding and producing a new leaf system following an attack.

The life cycle of the oak moth has four stages: egg, caterpillar (larvae), pupa (resting stage), and adult moth. Eggs hatch into hungry larvae which feed upon the leaves of oaks, eating all but the coarser leaf veins. After reaching a length of about one inch, the smooth-bodied, yellow striped larvae enter the resting stage by enclosing themselves in pupa cases. The tissues are reorganized to form the adult moth. Adults emerge as pale brownish moths with wingspans of slightly more than one inch. Being poor fliers they reproduce and deposit their eggs within or near the tree of their birth, unless carried farther away by winds.

Adults deposit eggs on the undersides of oak leaves in June or July. By October or November this summer generation has completed its lifecycle and the new adults similarly deposit the eggs of the winter brood. The winter generation takes about nine months to complete its life cycle, since the cooler weather slows down the feeding activities of the larvae.

While the oak moth is always present in the oak woodland, it occasionally occurs in populations of tremendous proportions for reasons which are not fully understood. Past records in the Bay Area would indicate that peak infestations have occurred at intervals of three to nine years. It was thought that natural enemies such as predatory bugs and parasitic wasps checked exploding populations. While these natural enemies undoubtedly play important roles in this regard, they do not seem to be prime limiting forces. It seems, rather, that the moth literally eats itself out of house and home: populations suddenly decline when the food source is depleted. Entire stands of totally defoliated oaks attest dramatically to the depleted food supply.

… While the ravages of the California oak moth seem quite severe at times, it should be remembered that this insect has been a part of the ecology of the oak woodland for thousands of years and the oaks are still here.

Linguistic note 2. From NOAD2:

noun frass: fine powdery refuse or fragile perforated wood produced by the activity of boring insects; the excrement of insect larvae. ORIGIN mid 19th century: from German Frass, from fressen ‘devour.’

To a friend who marvelled at this bit of lexicographic gold: Yes, there’s a word for caterpillar shit.

(Then there’s the fressen / essen distinction. In standard German, essen is the neutral verb for ‘eat’, fressen the verb for eating by animals, hence also used for ravenous or brutish eating by human beings (‘eat like a pig’). And as a coarser synonym for essen. And in some German varieties, for eating in general, with essen reserved as an elegant variant — certainly the case in Pennsylvania Dutch English (so that kids from my dialect area learning standard German had to learn how to deploy essen).)

Tussock moths and their kin. The larger family, from Wikipedia:

The Lymantriinae (formerly called the Lymantriidae) are a subfamily of moths of the Erebidae family.

Many of its component species are referred to as “tussock moths” of one sort or another. The caterpillar, or larval, stage of these species often has a distinctive appearance of alternating bristles and haired projections. Many tussock moth caterpillars have urticating hairs (often hidden among longer, softer hairs), which can cause painful reactions if they come into contact with skin. [on urticating, see below]

The subfamily Lymantriinae includes about 350 known genera and over 2,500 known species found in every continent except Antarctica.

Lymantria means “defiler”, and several species are important defoliators of forest trees, including the gypsy moth Lymantria dispar, the douglas-fir tussock moth Orgyia pseudotsugata, and the nun moth Lymantria monacha.

And the Western tussock moth, Orgyia vetusta. From the Stanford Report of 4/4/07, “Note to caterpillars dangling under the oaks: Meet the beetles” by Michael Peña:


Western tussock moth caterpillars create their cocoons in the oaks where they hatch and feed. But they descend on silk threads to find another place to pupate when trees get too crowded, which is very much the case this spring. Grounds Services is taking an integrated pest-management approach by releasing microscopic worms [nematodes] and spined soldier beetles, as well as power-washing trees and surfaces where eggs are laid and cocoons are left.

The article assured readers that the nematodes and soldier beetles are entirely harmless to people.

Linguistic note 3. From NOAD2:

verb urticate: cause a stinging or prickling sensation like that given by a nettle: (as adjective urticating): the urticating hairs. ORIGIN mid 19th century (earlier (mid 17th century) as urtication): from medieval Latin urticat- ‘stung,’ from the verb urticare, from Latin urtica [‘nettle,’ from urere ‘to burn’]

So tussock moths are likely to nettle you.

Linguistic note 4. On the genus name Orgyia, from the BugGuide site‘s section “Origins of names (Entomological Etymology)”:

From Greek orgyia (οργυια, from ορεγειν stretch out) meaning “the length of the outstretched arms”, a fathom, referring to the insect’s habit of extending the forelegs.

… Orgyia (Lymantriid moth), is Greek for “length of outstretched arms”, i.e., a fathom — the author, Ferdinand Ochsenheimer, was an actor and playwright [as well as a distinguished lepidopterist]

Yes, I know, you saw the orgy in Orgyria and were hoping for wild, licentious insect revels. But no, just an accident. From NOAD2:

noun orgy: a wild party, especially one involving excessive drinking and unrestrained sexual activity: he had a reputation for drunken orgies. • excessive indulgence in a specified activity: an orgy of buying. • (usually orgies) historical secret rites used in the worship of Bacchus, Dionysus, and other Greek and Roman deities, celebrated with dancing, drunkenness, and singing. ORIGIN early 16th century: originally plural, from French orgies, via Latin from Greek orgia ‘secret rites or revels.’

orgyria vs. orgia.

Oak processionaries. Well, there’s worse on the chenillar front, though not in Palo Alto or at Stanford — instead, they’re on the march in the UK. From Wikipedia:


The oak processionary (Thaumetopoea processionea) is a moth whose caterpillars can be found in oak forests. They may pose a human irritant because of their poisonous setae (hairs), which may cause skin irritation and asthma.

The moths are widely distributed in central and southern Europe, and are occasionally found as far north as Sweden. In the southern countries of Europe the populations are controlled by natural predators, but these predators do not exist in northern Europe. Their range is expanding northward, possibly or partly as a result of global warming. The moth now has an established population in the UK. The eggs arrived on oak imported to the Richmond and Ealing areas of London in 2006 and the range of the species in the UK has been steadily expanding despite efforts to eradicate it.

… The larvae construct communal nests of white silk from which they crawl at night in single file, head to tail in large processions to feed on foliage in the crowns of trees, returning in the same manner.

Oak is its preferred food source, but the moth also eats the leaves of hazel, hornbeam, sweet chestnut, birch and beech.

… The moths pose an increasing threat to humans as their range is extended. The backs of older caterpillars (3rd to 6th instars) are covered with up to 63,000 pointed defensive bristles containing an urticating toxin (thaumetopoein or closely related compounds). The setae break off readily, become airborne and can cause epidemic caterpillar dermatitis (lepidopterism), manifested as a papular rash, pruritus, conjunctivitis and, if inhaled, pharyngitis and respiratory distress, including asthma or even anaphylaxis. However, there have been no known deaths related to or caused by such exposures to this toxin.

A nightmare creature.

Linguistic note 5. From Wikipedia:

Lepidopterism is an irritant contact dermatitis caused by irritating caterpillar or moth hairs coming into contact with the skin or mucosa. When referring to the cause, moth dermatitis and caterpillar dermatitis are commonly used; Caripito itch [from an epidemic form that broke out in Caripito docks in Venezuela] (known as papillonite in French) is an older name referring to the moth dermatitis caused by some Hylesia species.

You might have thought that lepidopterism is merely what a lepidopterist (‘a person who studies or collects butterflies and moths’ (NOAD2)) does — as hypnotism is what a hypnotist does — but no. Instead, it’s a medical condition related to lepidoptera, like alcoholism vis-a-vis alcohol.

From Michael Quinion’s Affixes site on the incredibly versatile derivational suffix –ism:

This is one of the most prolific word-creating elements in the language. Beyond the 2000 or more that are recorded in large dictionaries, many others are formed as need arises, often for a single use.

The sense nearest to its Greek roots is that of some action or its result: baptism, criticism, exorcism, ostracism, plagiarism, volcanism. Derived from that is the sense of some state or quality: barbarism, egotism, heroism, hypnotism, isomerism, magnetism, organism.

As a further stage in its development it has come to denote a system, principle, practice, doctrine, or ideological movement. This is now its main sense, to the extent that ism was created in the late seventeenth century for a distinctive practice, system, or philosophy, typically a political ideology or an artistic movement, often with derogatory undertones.

Examples of some recent, often temporary, formations (out of a very large group) include hacktivism (the movement comprising people who hack into and damage computer systems as a political act, modelled on activism), knee-jerkism, New Labourism, presenteeism (the principle of staying at work for excessive hours out of anxiety for one’s job, the opposite of absenteeism), rejectionism (a political viewpoint in which the whole of a policy is rejected without possibility of compromise), shopaholism (the state of being addicted to shopping), youthism (an emphasis in fashion and the media on young people to the exclusion of other age groups).

Two other specific senses are worth noting. Some stand for a peculiarity in language (colloquialism, syllogism), especially that of a particular group (Americanism, Cockneyism, Irishism) or some point of style characteristic of a writer (Hitchcockism, of the film director Alfred Hitchcock; Pratchettism, of the writer Terry Pratchett). Some denote a pathological condition: alcoholism, cretinism, embolism.

In some of these patterns, nouns in -ist correspond to nouns in -ism (hacktivist / hacktivism), but these correspondences are very imperfect.

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