“The Botanists Among Us: Host plant specialization in insects”

It’s been a busy week for me—just two days after doing a presentation on tiger beetles to the Webster Groves Nature Society’s Entomology Group, I gave a talk to the St. Louis Chapter of the Missouri Native Plant Society. As implied by the title, the talk focused on host plant specialization among insects, first covering the major groups of plant-feeding insects and the evolutionary themes involved in adaption to (and away from) plant-feeding, then moving to examples of different types of host plant specificity and highlighting some of the more interesting insects that I’ve encountered (and managed to photograph) over the years.

Like my talk two nights earlier, it was another fun and lighthearted conversation with a highly engaged crowd, and I appreciate the great interest shown by a group that is normally much more focused on plants than on insects. Once again, it was well-attended locally, but for the benefit of those who were not able to attend the meeting in person and that may be interested in this subject, I’ve prepared a PDF version* of the presentation that you can download and peruse at your convenience.

* All content is copyrighted and may not be reproduced or distributed without written consent.

© Ted C. MacRae 2019

Monday Moth – Polka-dot Wasp Moth

Syntomeida epilais - polka-dot wasp moth

It’s been a while since I’ve done a Monday Moth post, so I thought I’d feature one of the prettier specimens in my very limited Lepidoptera collection.  This is Syntomeida epilais (polka-dot wasp moth), one of four species in the genus that occurs in the United States.  This particular specimen was collected by me way back in the mid-1980s (I was not quite yet the discriminating beetle collector that I am now) in Everglades National Park (yes, I had a permit).  The bright, contrasting coloration obviously screams aposematism (warning coloration), and in fact the tissues of the adult moths of this species are chock-full of several cardiac glycosides sequestered by the larva from its now preferred food plant, oleander (Nerium oleander).  Add to it their somewhat wasp-like appearance, and there should be no question to any would-be predator that these moths are a bad idea.  Wasp moths are related at the tribal level to another group of wasp-like moths called maidens which are restricted to the Old World.  I featured one of these from South Africa last year in the post, Monday Moth – Simple Maiden (Amata simplex).

If the cardiac gycosides stored in the tissues of this moth aren’t enough to cause gastric distress, trying to digest the higher taxonomic history of this group surely will.  Back in my school days, this moth belonged to the family “Ctenuchidae.”  As best I understand it, this group was later subsumed into the tiger moth family “Arctiidae” – itself later subsumed within the borg of all moth families, the Noctuidae.  In the most recent classification I’ve found, the arctiine moths have been pulled back out of the Noctuidae and combined with the former “Lymantriidae” (propelled to infamy by the gypsy moth) to form the family Erebidae (Lafontaine and Schmidt 2010).  Are you ready to purge yet? It’s still not clear to me whether this latest incarnation represents a consensus monophyletic unit, but it really doesn’t matter – whenever I see wasp moths, maidens, and especially the ctenucha moths that are so common in my area on goldenrod flowers during the fall, “ctenuchid” will still be the first name that comes to my mind.

REFERENCE:

Lafontaine, J. D. and B. C. Schmidt.  2010.  Annotated check list of the Noctuoidea (Insecta, Lepidoptera) of North America north of Mexico.  ZooKeys 40:1–239.  doi: 10.3897/zookeys.40.414

Copyright © Ted C. MacRae 2011



The Moth and Me #11

The Moth and MeWelcome to issue #11 of The Moth and Me, the monthly carnival devoted to the “forgotten” lepidopterans. Most people – even entomologists – regard these as the lesser leps, denizens of the night, as if to hide their somber-colored drabness from the flashy brilliance of their rhopaloceran relatives. Of course, this simply isn’t true, as the contributions to this month’s issue well demonstrate. Butterflies may be among the largest insects on earth, but the largest lepidopteran in the world is a moth. They may also be as gaudily colored as the rainbow itself, but what butterfly is more colorful than the Urania day-flying moths (the genus name literally means, “The heavenly one”).   And, they may be almost universally accepted by a largely insect-indifferent public, but who among us does not think back to that first sight of a luna moth as the most stunning insect we had ever seen to that point.  Yes, moths are all that butterflies are, and for this month’s issue of TMaM, 15 contributions by nine writer’s show us why.

Family Saturniidae – Giant Silkworm & Royal Moths

Tales from the Butterfly Garden: LepcuriousLuna moths belong to the royal moths of the family Saturniidae, and as the name implies they are not the only stunningly beautiful member of the group. Kristen at Tales from the Butterfly Garden: Lepcurious writes about an encounter with the Sweetbay Silkmoth (Callosamia securifera).  Like other members of the family, larvae of this species are rather particular about the type of tree that they utilize for food, which in the case of this moth is sweetbay (Magnolia virginiana).  I’m a little too far north here in Missouri for this tree, so I have never seen this moth.  However, I have seen (and reared) some of its close relatives, the Promethia Silkmoth (Callosamia promethea) which hosts on several plant species and the Tulip-tree Silkmoth (Callosamia angulifera) which hosts on Tulip Tree (Liliodendron tulipifera).

Family Zygaenidae – Leaf Skeletonizer Moths

xenogereJason Hogle at xenogere is fond of the unusual and has a gift for finding it. In his post The Unmoth, Jason shows us a male grapeleaf skeletonizer (Harrisina americana) – not your typical moth!, The uniformly black color and bright red neck collar just screams “Don’t eat me – I’m poisonous”, and indeed species in this family are among the few insects capable of producing hydrogen cyanide!  As the name suggests, larvae skeletonize the leaves of both wild and cultivated grapes (Vitis spp.), as well as the related Virginia creeper (Parthenocissus quinquefolia).

Family Noctuidae – Noctuid Moths & Tiger Moths

Tales from the Butterfly Garden: LepcuriousRoyal moths are not the only stunningly colored moths that Kristen at Tales from the Butterfly Garden: Lepcurious has found in Florida, as she shows in this post on Oleander Moths (Syntomeida epilais) and a companion piece on its Oleander host plant.  This striking day-active moth, also called Uncle Sam Moth (for its red, white, and blue colors) and Polka-Dot Wasp Moth (for obvious reasons), may seem like an easy-to-spot target for would be predators, but its gaudiness is actually warning of the toxic chemicals it has sequestered in its body from the Oleander on which it fed as a larva.  Oleander contains the toxins oleandrin, a cardiac glycoside, and neandrin and is toxic if ingested.  Although oleander is an Old World exotic, oleander moths may also be found feeding on devil’s potato vine (Echites umbellata), which may have been their native Florida host before the introduction of oleander to the United States.

See TrailAside from the underwings (genus Catacola) and the recently incorporated tiger moths, Noctuids are typically thought of as the “basic brown moths” – relying on just the aforementioned groups to add a splash of color to the family’s otherwise drearyness.  Nothing could be further from the truth – check out the stunning Eight-spotted Forester (Alypia octomaculata) in this post by Matthew York at See Trail. Larvae of this beautiful little moth feed on ampelopsis, Virginia creeper, and other plants in the grape family (similar to the grape leaf skeletonizer above). “A great moth; brilliant color, diurnal…… and yes… Noctuid. Some moths, like people, don’t go with the trends.”

See TrailFor the most part, tiger moths shun the daytime in preference for the safety of the night. That does not mean, however, that they are any less colorful, as Matthew York at See Trail shows in his post Poor Grammia. Notarctia proxima, the Mexican Tiger Moth, and its relatives have had a bit of name shuffling over the years at the hands of taxonomists – formerly placed in the genera Grammia and Apantesis. Whatever name you call it, the striking white and black striped forewings give a clue about their common name of tiger moths, and the red, black-tipped abdomen not only add to its beauty, but belies the defensive compounds it surely contains.

Speaking of tiger moths and defensive compounds, watch the video that Chris Grinter at The Skeptical Moth included in his post Moth Perfume. In it, Chetone angulosa gives a striking display of a common defensive mechanism for the group – excreting hemolymph (sweating blood, so to speak!). So spectacularly does the moth do this that you can actually hear the hissing sound of the fluid being pumped from the body. Moreover, there seem to be at least a couple of active ingredients in the froth – one that smells like peppermint, and another that causes numbing of the tongue (as Chris can testify firsthand – he is a truly dedicated experimental naturalist!).

Karthik's JournalIn similar fashion to our North American species of underwing moths (Catocola spp.), the related Eudocima materna, one of the fruit-sucking moths of south India, uses its drab-colored forewings to hide its brilliantly colored hindwings, as Karthik at Karthik’s Journal shows us in his post Startling Displays.  This forms a double line of defense against would-be predators – the forewings blend marvelously into the color of the tree trunks upon which it rests during the day, camouflaging the insect and making it nearly invisible.  If this doesn’t work, a sudden flash of the hindwings may startle the predator just enough to allow the moth to take flight to another tree – where it instantly “disappears” as soon as it closes its wings.

Snails Eye ViewAustralia also has some very colorful fruit-piercing moths, and Bronwen Scott at Snails Eye View presents some beautiful photos of the particularly strikingly-colored Othreis iridescens. Like other members of the group, this Far North Queensland endemic feeds on fruit (Pycnarrhena novoguineensis and Hypserpa laurina, both Menispermaceae, in the case of this species), but as it is apparently the rarest of the primary fruitpiercing moth species in Australia it is not considered to be a pest (and Bronwen would cut it some slack even if it was!).

EntophileAdults are but only one of four life stages that all moths go through. If moths are the “forgotten” leps, then caterpillars are the “forgotten” moths. In many cases, the caterpillar stage cannot be recognized until it becomes a moth (and in some cases the caterpillars are completely unknown). Fortunately, Navy entomologist corycampora at Entophile recognized the caterpillar he found on his croton bush, which he features in the post Croton caterpillar, Achaea janata (Linnaeus), (Lepidoptera: Noctuidae). These “eating machines” can be just as fascinating to observe as their scaled adult counterparts, and while croton seems to be a preferred host in Hawaii, it apparently also feeds on castor beans (judging by its other common name, Castor Oil Semi-looper).

Family Notodontidae – Prominent Moths

the Marvelous in NatureOften dismissed as noctuids, the prominent moths tend to be fuzzier, more thickly-bodied moths that rest with their wings curled around their abdomen or tented over their back (rather than flat like noctuids and most other moths). TMaM organizer Seabrooke Leckie at the Marvelous in Nature has a love affair with prominents, and in her post Georgian Prominent, she features the nicely thick-bodied and fuzzy Georgian Prominent, Hyperaeschra georgica. The caterpillars of this widespread species feed on oak (Quercus spp.), thus, unless you live in the Pacific Northwest you stand a good chance of encountering this species – if you’re you’re willing to make the effort.

Family Psychidae – Bagworm Moths

xenogereMany of us are probably familiar with the evergreen bagworm moth (Thyridopteryx ephemeraeformis), whose large, cone-shaped bags almost look like fruit hanging from the evergreen bushes on which the caterpillars feed. But did you know there are other species of bagworms as well? Jason Hogle at xenogere does, and he compares and contrasts two of them in this duo of posts, Rainy day on the patio and The Other Bagworm. One huge and prominent, the other (Dahlica triquetrella) very small and oft unseen. One with all manner of plant matter stuck to its bag, the other usually mistaken for small bits of dirt or wood. Jason is so good, he can even determine the sex of the caterpillar inside the bag!

Family Sphingidae – Hawk Moths

Roundtop RumingsCarolyn at Roundtop Rumings is hoping that somebody can Name this moth, which she found on the door of her cabin in the forests of Pennsylvania. Don’t let her inability to name this moth fool you, however, for her post contains loads of information on exactly the kinds of characters one should take note of when trying to identify hawk moths. Large size and membership in a popularly studied group aren’t enough – what do the hindwings look like? Are there any spots on the abdomen? As a coleopterist, I hesitate to offer my relatively uninformed opinion on the exact genus and species for this moth, but I’m going to go out on a limb here and suggest maybe something in the genus Ceratomia, perhaps the waved sphinx (C. undulosa)?


I hope you have enjoyed this issue of The Moth and Me, and my sincere thanks go out to all of those who contributed!  The hosting slot for next month’s issue of TMaM is still open, but you can submit your contributions anyway to Seabrooke Leckie at the home site for inclusion in the June 2010 issue once a host is selected.  The submission deadline is June 13, with the issue appearing a few days later.  Perhaps you might like to host the June issue – hosting is not only fun, but also a great way to introduce readers to your site and generate a little traffic.  Contact Seabrooke at the home site if you’re interested – I’m sure she would love to hear from you.

Copyright © Ted C. MacRae 2010

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Monday Moth – Trichaeta pterophorina

 Trichaeta pterophorina – Borakalalo National Park, South Africa

Another photo from the South Africa files, and one that continues the mimicry theme that has been featured in several recent posts. It’s not a great photograph – the focus is off – but the colors these moths sport are dazzling, and there is a nice symmetry to their tail-to-tail mating position.

Roy Goff, author of the website African Moths, tells me this species is the Simple Maiden (Amata simplex) in the family Arctiidae (whose ~2,000 species worldwide are increasingly considered a subfamily of the already enormous Noctuidae) [update 6/20/2012—Martin in a comment considers these moths to actually represent Trichaeta pterophorina in the same subfamily].  Its gestalt – greatly resembling a stinging wasp – brings to mind the so-called “wasp moths” of North America (subtribe Euchromiina); however, maidens belong to the exclusively Old World Syntomina.  Like the wasp moths, most maidens are exceptionally colorful and exhibit clearly aposematic patterns.  While these might seem to be textbook examples of Batesian mimicry, most species in this group are also protected by distasteful secondary plant compounds that they sequester through feeding, making them Mullerian rather than Batesian mimics.  These compounds are not only acquired by larvae from their food plants, but also by adult moths who imbibe them from fluid regurgitated through their proboscis onto dried parts of plants containing the compounds and into which they dissolve.

Their aposematism is not limited to strictly visual cues.  An Australian species, Amata annulata, is known to regularly emit ultrasonic clicks when flying, thought to be aposematic behavior to warn bats of its distastefulness in the same way that that its coloration warns daytime predators. Additional defensive characters that have been described for species in the group include frothing and extrusion of defensive processes. Clearly, maidens are leaders in the arms race among the insects!

Copyright © Ted C. MacRae 2010

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