So Why Spiders?

Truth-in-blogging-disclaimer: Much of what follows was a response to a question on Quora.com, viz: “Why do you like spiders?” I have been asked this a number of times, and thought that I’d really rather direct people to my admittedly often-ignored-blog than to Quora, so with some minor changes, this is how I answered that question:

First, though, the non-asked question “Why bugs?” is easy: I was born an entomologist. My earliest memories are of collecting insects, and my mother always told me that, as a baby, I would lie in my playpen and watch the ants rather than play with toys. At age 8, when I learned it could be done—and that it would be would be essential for a professional career—I decided to get a Ph.D. in entomology.

I remember, too, at age 4 when we lived in Douglas, Arizona, I would go into the garage and kill the “black widows” therein—and black widows only*👇, as I had been told to leave them alone, their being “bad” spiders and potentially dangerous.

Now, it’s true that spiders aren’t insects, of course, but as it turns out, educationally, entomologists get the arachnids, and plant pathologists get the nematodes. So I had always had a general interest in spiders, flies, and beetles…at least somewhat more than in most other arthropods.

What really got me interested in spiders, though, was one particular observation that I made in the 1970s, while I was in grad school studying entomology. One day, while driving from home to school, I noticed an adult female Phidippus audax (a robust and very common jumping spider) peeking out from the edge of my sun visor while resting upside down on the car’s headliner.

<i>Phiddipus audax</i>
Phiddipus audax, the bold jumper

Now, as might be imagined, jumping spiders stalk their prey and, when close enough, um… jump on it. This particular spider was stalking a fly, also upside down and resting on the headliner about 4 inches from the sun visor. The spider crept out stealthily closer to the fly, and then suddenly leapt at the fly. The fly, of course, flipped and took off.

The spider intercepted the fly’s trajectory, grabbed it in mid-flight, and, thanks to its ever-present drag line, swung down with the fly, climbed back up the drag line, and carried its prey back behind the sun visor for a leisurely lunch.

I was thinking: no big deal, right? Spiders do this all the time.

But then it dawned on me that the spider and its prey had been upside down. Thus, it’s impossible for a spider to jump from one spot on a headliner to another, because as soon as it jumps, it begins to fall, i.e., gravity makes it impossible for the spider to jump onto the fly, instead, the spider’s downward trajectory had to intercept the fly’s!

Now, how did the spider know this? Do upside down jumping spiders “know” they’re upside down? Do they “know” their prey will have a downward trajectory, too?

And so I wondered: How on earth did that spider ever catch that fly? Luck?

That one incident led me to focus on spider biology and behavior. Spiders never became my job. I did teach Araneology at Cornell, but that was not the main focus of my job there. Instead, it was something I undertook owing to my passionate interest, an interest that has never waned.

And, speaking of gravity…


* Probably the western black widow, Latrodectus hesperus, but my parents called them simply “black widows.” *👆

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Bugs…and Music!

Those who know me from my musical instrument retailing days understand why my email addresses feature “music.” And, owing to that first sentence, those who have known me only as an entomologist now understand the origins of those addresses, too!

I suspect that had persistent email addresses existed in the 1970s, my email would have been arthropod-related. Come to think on it, I still have a working Yahoo email address from 2000 that also combines both interests, viz.: musicmygale@yahoo.

Anyway, combining those disparate interests–entomology from birth, music since 1958–had never been something I sought to do…until now (although I do rather like the fiddle tune Spider Bit the Baby).

So, owing to the following cascading–if bizarre–sequence of events, I have, indeed, combined music and spiders:

  1. A high school friend sent a me Haiku he wrote regarding COVID-19.
  2. In consequence, I, too, started writing in Haiku (he 5-7-5 syllable version) and started a Facebook group called “Surviving COVID-19 with Haiku.”
  3. I awoke one morning thinking*👇: “Gee, it would be hard to fit the scientific name of the common house spider, Parasteatoda tepidariorum (C. L. Koch, 1841) into Haiku format. So I did, of course, and posted same on my personal FB page, its having nothing to do with the trumpandemic.
  4. In response, one of my real-life FB friends jokingly suggested it should be a children’s song, so I
  5. jokingly replied that the words “Parasteatoda tepidariorum” would fit quite nicely into the melody of Gary Indiana, the song from Meredith Willson’s 1957 musical, The Music Man. So, naturally I
  6. wrote some words to fit.

Herewith my version, called (cleverly) Parasteatoda tepidariorum:

And yes, consider this to be a warning that I shall post another spider song anon.

Preview(opens in a new tab)


Technical notes for non-biologists:

  1. P. tepidariorum is one of the most common spiders living around humans (i.e. “synanthropic.”)
  2. A “scientific name” has two parts: the genus (“Parasteatoda”) and a specific epithet (“tepidariorum“). Thus, a scientific name can also be called a “binomial,” as I’ve used it in the song.
  3. Once one has stated the genus, it can be abbreviated to just its first letter–as I did in (1), above, and in the song.
  4. Barring some major error–such as describing as new a species that someone else has already published–the specific epithet stays with the organism forever, though the critter can be reassigned to another genus–which often happens. When it does, the name of the original author is placed in parentheses, as in this case.
  5. P. tepidariorum has bounced around from genus to genus in the last 179 years, having also been called Steatoda tepidariorum and Achaearanea**👇 tepidariorum, as well as a number of other names declared to be invalid synonyms. (If you really want to know, visit this page of the World Spider Catalog.)

Technical notes for non-musicians:

  1. Despite what you’re hearing, I used to be a decent guitar and banjo player, having
  2. not only played in quite a few bands, but
  3. having taught “professionally” starting in a music conservatory in 1964 and continuing privately until 2020.
  4. I stopped teaching largely owing to the combined effects of a broken left thumb and rather painful osteoarthritis in each hand.
  5. So, if you’re to judge my playing, please either listen to my MP3s or visit my Youtube channel–these repositories contain hundreds of recording of my playing instruments (mostly banjos) that I was trying to sell.

*👆 Weird, perhaps, but not at all out of character.

*👆 I learned this species as Achaearanea tepidariorum when It took Araneology in grad school. It became my favorite binomial, simply because of its comprising 12 syllables for such a tiny animal! My first response to its being put into Parasteatoda in 2006 was one of loss and disappointment. But then, I realized that it still has all 6 syllables and the word certainly scans better than Achaearanea for use in song or poetry! So it’s still my favorite name to bandy about.

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What’s This Doing Here?

On 29 May, 2019, as I was walking into my house, I noticed a male spitting spider (that’s for real: the members of the family Scytodidae are called spitting spiders for good reason!) on my office’s door frame. I had seen 2-3 of them in the house we have inhabited for ca. 3½ years, but I honestly had not paid them much attention, as one species, Scytodes thoracica (Latreille, 1802) is fairly common, and–while they are consummately cool spiders–I had stopped collecting ca. forty years ago, and have not been actively involved in any spider activity other than the occasional and casual observation of them for the intervening decades.

My mystery Spider

So I really didn’t think much about this spider until I had gone inside the house, and mused about the fact that I had never seen S. thoracica outdoors before.

I went back out and looked at it some more, and realized that it simply didn’t look like S. thoracica, with which I had been familiar since….I don’t know: forever? So I went back inside and did some cursory research to see if we had other spitting spiders in North Carolina, and learned that another species, S. longipes Lucas, 1844, has appeared here and there in the area, and was extending its range northward.

bugguide.net/node/view/657373(opens in a new tab)

So I decided this must be S. longipes, apologized to it, and preserved it in alcohol so that I could examine its microscopic features (the structure of the male pedipalps, if you must know) to see if it was, indeed, not S. thoracica. It was decidedly not, so I naïvely figured I had found S. longipes, and put the now-pickled spider aside.

On 30 April 2020, I found a dead male Scytodes on my bathroom floor. Fortunately, it was freshly dead (i.e. still flexible but not rotten), so I pickled it, and set it aside.

Sometime that May, I went out one evening and found three scytodids concurrently on a different door frame. Foolishly, I did not collect any, or even note the date, still assuming all of these to have been S. longipes.

A few weeks later, my pet black widow died (awww…), so I got out my microscope for my son, Benjamin, to look at her cadaver. When he was finished, I figured I’d take a look at the bathroom Scytodes to see if it, too, was possibly S. longipes. Examination of its palp indicated it was indeed the same species. But this time, figuring something was going on, I dug into the literature to verify their really being S. longipes, and…they clearly weren’t!

Intrigued, I dug deeper, looking for palpal structures that looked like the spiders at hand. After many hours of reading papers (going back to 1837), I found a 2007 paper by Cristina Rheims, Antonio Brescovit, and César Durán-Barrón on Mexican species of the genus Scytodes, in which they described 13 new species. One of those new species, S. atlacoya, had palpi similar to those of my specimens, and unlike those of any other Scytodes I could find.

On 26 May, I sent an email to each of the authors (the first two in Brazil, the third in Mexico) with crude photographs of my spiders and their palpi, asking if they thought I might have a Mexican spider now in North Carolina. Naturally, the response was “could be, but we can’t tell without seeing the specimens” (Hey, I was happy simply to hear back from each of the three authors, and had been hoping for that very answer!).

I packed up the two male spiders and made arrangements to send them to Brazil (Señor Durán-Barrón proclaims himself not to be a Scytodes expert, but had “merely” sent the Mexican specimens to Dr. Rheims and Senhor Brescovit, each of whom is).

After sealing that carefully prepared shipment, I walked outside on the evening of 29 May 2020 (one year to the day after finding that first male) and saw a female Scytodes (again on a door frame!) who looked suspiciously like my male specimens. Naturally, I collected her and examined her genitalia (sorry, but that’s how one does it with spiders!).

Sure enough, she, too, looked to my eye likely to be S. atlacoya! So on 02 Jun 2020, I repacked everything, emailed a photo of her genitalia (an admittedly scientifically useless photo) to Brazil, repacked the now-three spiders, and sent them off to the lab in São Paulo, where they arrived safely 09 Jun.

A Female Scytodes atlaoya

On 28 July Senhor Antonio Brescovit, who had been quarantined away from work (thanks, COVID), was able to go back to his lab and confirmed that the specimens I had sent are, indeed, S. atlacoya Rheims, Brescovit, and Durán-Barrón 2007.

“So what?” I hear you ask? Well some research revealed that only few specimens have been reported in the USA: a few in TX, a couple in OK, and some in MS, FL, and GA: but none had ever been recognized in NC.

Meanwhile, I kept finding these spiders all over my house and even some in my tool shed. One night, I went out with a light and observed 27 of them on the side of my house, 11 of them on my front porch, and about 20 of some very young spiderlings by the door where I collected the first female (though not her offspring–their mother and five of her kids live on my desk at this writing)!

I have since been observing their behavior and rearing them from eggs; and have already learned a lot about them. They also prompted me to buy a macro lense for our DSLR, so I can actually get some closer shots now.

A female carrying her egg sac (from which hatched >50 spiderlings)

So I’m sure I shall be adding more information here as things develop. Suffice it to say, this old spider-nerd is really enjoying himself these days!

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To be a Kid Again

I’ve been an entomologist all my life, as both avocation and vocation. I started collecting when I was ca. 4, while living on the Mexican border of Arizona. I remember well my particular fascination with spiders even then, especially the Latrodectus sp. in our garage.

My formal education thus focused on economic entomology, as I figured that there would always be abundant jobs available in that field–a supposition that proved correct. 

When I left grad school and took a job on a university faculty, my official responsibilities were research and Coöperative Extension, but I specifically asked that I also be allowed to teach, and subsequently not only taught salient topics in several courses not of my own, but put together and taught a graduate level course called “Araneology” (my interest was spiders, so I didn’t wish to dilute my course with in-depth inclusion of other arachnids*).

Eustala anastera (Walckenaer, 1841),
ca. 20mm


I left academia in 1982, selecting vastly better remuneration over academic interests–a choice that in some ways I still theoretically regret**– and took a job in a corporate environment.

At that point, I completely stopped collecting insects and spiders as I realized that my specimens no longer had scientific value to me or anyone, and therefore it was pointless to be killing critters merely to pin them in boxes or to preserve them in alcohol.

(Now, to digress a moment, I have long described myself as being “visually tone deaf.” I have no visual artistic skills (I’m also aphantasic), and–while I know how to operate a camera and take snap shots–I am in no way a photographer.)

(And now I regress) I recently became intrigued by a local spider species, and wished to have photos of it to show others internationally. My cell phone’s macro function is terrible, my old video camera also sucks at macro, and the stereo microscope I have was way too “strong,” even at its lowest magnification. 

Then I remembered the DSLR I had bought as a present for my better half, Carmen, ca. 11 years ago. One of the specific reasons I bought it was the ability to change its lenses, and sure enough, a bit of searching and an $85 investment got me a halfway decent macro lens that did the trick***.

And now I have happily been collecting photographs such as these instead of boxes and vials of dead bugs.

Mecynogea lemniscata (Walckenaer, 1841), ca. 10mm

It’s hard to describe the level of satisfaction I am feeling having rediscovered my youthful passion for collecting critters, and how comforting it is to have found a non-destructive outlet for a lifelong obsession!

+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=

*I have nothing against other arachnids: I had time constraints and wanted my course to focus on spiders.

**When I say “regret” it is with the awareness that life does not have alternate endings: Every tiny happenstance in people’s lives alters their and others’ futures. My life has been immensely rewarding, and there is nothing I would change, as any changes would have prevented me from being happily at the point I am.

***The photos I have interspersed are simply to show how I spend my time–they’re probably lousy, but I wouldn’t know the difference, so please don’t tell me.

****E.g. Just this week I found a spider that I would need to examine closely to make an accurate ID. So I decided to kill her by freezing preparatory to pickling her in alcohol. She had been in the freezer for only a few minutes when I changed my mind, as I really didn’t want to kill her, so I fetched her from the freezer to let  her go. She was not yet frozen, but was already torpid, so I was able to ID her before she warmed up enough to move and then to release her whence she had come.

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To be specific…

One of the most common questions I get asked by people on social media and in person is: “What is this [insect|bug|spider]?” And, that’s a fair question–we humans really like assigning names and putting labels on things.

But what is the “what is this?” question really asking? Or, as the Bard put it: “What’s in a name?” Surprisingly, often merely being told a name is sufficient. I say “surprisingly” because knowing a name usually tells us absolutely nothing. What it does do is to afford a means of subsequently learning something about the organism at hand (and yes, that very same question is asked about plants, fungi, etc.).

But here’s another question that needs to be addressed: What is a species? If you look up the biological definition, you’ll find a lot of wiggle room and/or weasel words. Generally speaking, though, a “species” is defined as a population of organisms that breeds within itself.

Unfortunately for classification systems though, living things almost never read the books about definitions and taxonomic rules*, and instead form a very broad spectrum that is not at all clear-cut. Thus, the observation that “dogs don’t interbreed with cats” is a good one, and does uphold the “interbreeding population” definition. There are, however, myriads of examples where the definition fails and isolated populations..considered to have been distinct species..are found to interbreed when seasonal, geographical, or even morphological barriers are removed.

“But” I hear you ask, “what about our knowledge about DNA? Doesn’t that settle things?” Nope. DNA helps to identify relatives, but even among members one species there is genetic variation. In fact, DNA analysis has recently suggested that Neanderthals (once considered a separate species, viz. Homo neanderthalensis) interbred with and were essentially subsumed by H. sapiens, such that they are now generally regarded to be a subspecies**: H. sapiens neanderthalensis.

The problem, as this illustrates, is that recent speciation is a blurry place. Species that split apart eons ago usually now have sufficient differences that they can no longer interbreed. But speciation is occurring all around us, on a daily basis–zipping along at a breakneck pace rivaling that of continental drift.

Of course, there are a few organisms that are easily determined*** by their gross morphological characters. Unfortunately, these tend to be “living fossils” or threatened species representing a genetic deadend. The tree Ginkgo biloba L. 1771 is one such species. In fact, not only is G. biloba the only species in the genus Ginkgo, it’s the only member of the family Ginkgoaceae, the order Ginkgoales, the class Ginkgoopsida, and the phylum Ginkgophyta! Now that’s one lonely species!

For most species, though, determination is best left to experts. Merely looking at pictures in books or on websites may provide some idea of what the organism in question is called–but it may very well lead the neophyte astray! This is why even (especially?) experts often will not tell you what they think some species is, but instead say something along the lines of “Oh, that could be XYZ, but I’d really have to have the specimen in hand to be sure.”

So perhaps instead of asking “What is this?” a better question might be “Can you tell me something about this?”

*Insofar as we know, there is only one species among the almost 2 million extant on this planet that does this.
** Don’t get me started on the whole sub-, super-, infra-, etc. designations.
**When folks identify organisms to the species level, they are said to “determine” them.

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Old Stuff

First off, that title well describes me, but that’s not what I mean.

No, I just found the columns that I wrote for publication almost 40 years ago. Back then, I was on the Cornell Entomology faculty, having responsibilities for ornamental plants, both nursery crops and woody ornamentals, when I was approached by a friend from Cornell’s Department of Floriculture and Ornamental Horticulture asking if I would consider writing something for the monthly edition of the New York State Flower Industries Bulletin. I said “Sure. Why not?”, and began to submit some insect-related writings each month, obviously targeted towards the floricultural industry in New York State.

Those who know me will recall I’ve had a long avocation of playing banjo and guitar, and I was smitten at the time by a tune I had recently learned called Beasties in the Sugar,  so I borrowed heavily, and titled my fledgling column Beasties on the Blossoms.

Unlike this blog, Beasties on the Blossoms had a real deadline, so I was honestly pretty good about getting it written on a timely basis, and kept at it from 1980 until I left Cornell for a job in industry in 1982.

About a year after my leaving, I was approached by the editor of Floral & Nursery Times to see if I would be willing to write a similar column for that publication. I agreed (especially as I was to be paid this time!), and some phone calls resulted in my getting permission from Cornell and the N.Y.S.F.I. to continue use of the Beasties on the Blossoms title, as well as this graphic that Cornell had designed for my use, as I hated the thought of having my picture on every column I wrote.

So Beasties on the Blossoms continued for another few years. I was also approached to write columns for Greenhouse Manager magazine and later for Florists’ Review, which was–and apparently still is–the premier publication for the floricultural industry. My association with the former was very brief, owing to artistic differences: I didn’t want my photo used with my column, Beasties Under Glass, and they insisted, so we parted company. My column for the latter, My Favorite Pests, had a photo at their insistence that all their columnists had photos and a signature, and they would make no exceptions. As the pay was good, and I didn’t want to turn down what was a major publication in the industry, I had a photo taken of me and one of my pets:

So what brings this all up? As I found a bunch of original pages and photocopies of most of my my columns, I have set about digitizing them for my family. Because, you know, Google just doesn’t find them!  Isn’t that amazing?  And, since I’m scanning them, I figured I might be able to use some here. After all, I had fun with them, made a (very) little bit of money, and enough people enjoyed them that I was not only encouraged to continue, but got a bunch of speaking engagements from them!

Herewith, my inaugural Beasties on the Blossoms column (click to enlarge):

 

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A Fraudulent–If Cool–Facebook Photo. And a Pet Peeve.

A neat photo of an ice sculpture was posted on Facebook in January 2016 with the comment “Frozen spiderweb found in Nantucket, Massachusetts.”

1780633_859339174187792_5154633696247283096_n

This brings to mind a pet peeve of mine–drawings of impossible webs.

An “orb web” is the well known spider web comprising a series of non-sticky silken lines forming a rough frame used to attach the web to something (trees, posts, small children, whatever) and other non-sticky  lines that radiate from the center of the web to support its prey-catching business part.

Typically, after creating the framework and the radial lines, the resident spider starts at the center of the web and goes ‘round and ‘round in a spiral manner, all the while laying a continuous strand of sticky “capture” silk. The capture silk is carefully attached to each radial line as it’s crossed, thus creating a ”net” for capturing prey on the sticky lines.

Now, not all spiders make webs, much less these orb webs, but still, it’s what most people think of when one says “spider web.”

So what’s my gripe?

Look at this illustration…bad_orb

Now look at this photo of an orb web:

sag_photo

See the problems? In the photo of a real web, the capture lines span the gaps between the radial lines. Some species pull the lines really tight, but others leave a little slack, and when this happens, gravity causes the capture lines to sag…downward.  Everywhere.

Look at that photo again, please. Now look again at the illustration.

Take a good look at the drawing of the “spiral” capture lines! Not a chance! How on the Flying Spaghetti Monster’s green earth could the vertical capture lines not only sag uniformly toward the web’s center, but actually sag upwards on the lower half of the web? Plus, of course, the capture lines in the drawing are concentric, not a continuous spiral.

Now do you see the problem with the “frozen web?”

A quick image search found this version of the non-cropped photo, where the giant ice “spider” at the bottom verifies the entire thing’s ice sculpture roots.

ice_sculpture

So please, if you’re going to draw orb webs (or crop a photo to claim it represents a real, frozen web), remember how gravity works on this planet.

(I won’t even get into the fact that there are two entirely different kinds of capture lines on the ice sculpture…look at the 9:00-10:00 position in the top photo–click on the photo to enlarge it.)

Extra points:  What’s up with this photo?

orb-weaver-spider-web

 

Answer:
¡uʍop əpısdn :ʎɐʍ sıɥʇ pəsn sɐʍ oʇoɥd əɥʇ

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Crypsis At Its Finest

Many arthropods are masters of crypsis, either being camouflaged so well that they’re almost impossible to see, or being such good mimics of other organisms that they are very difficult to tell apart.

Today, I want to share some neat info about a moth larva that does a bit of both.

In specific, slightly more than four years ago, I walked out onto our deck to discover this large “inchworm,” i.e., the larva of a geometrid moth (also commonly called spanworms, geometers, cankerworms, or loopers) on the gate:

Now, I don’t have any idea what species this is.  I didn’t kill the larva, so I really didn’t (don’t) have any way to determine it, so we’ll just be happy calling it a geometrid (that means it’s in the family Geometridae).

IMG_8413

Anyway, pretty clearly it’s camouflaged really well to look like a twig; you can imagine that if this caterpillar had been holding onto a branch with its prolegs (the fleshy, false “legs” on the rear segments of most caterpillars) instead of a red-stained gate, I probably wouldn’t have seen it.

It’s hanging belly up so at the right end you can see where its six true (jointed) legs pointed are tucked in and pointed skyward.

So score a very strong point for camouflage.

But this beastie isn’t done–it turned out also to be mimicking a small snake.

If we look at this critter head-on in this upside down shot you can see the faint Y mark of the head’s frontal sutures.  This would be its “face”…if caterpillars had faces.

head_legs

As caterpillars are larval insects, they have six true legs, one pair on each segment of the thorax. The way this caterpillar is hanging, you can see four of them partially: just to the right of the head is the very tip of the leg on its 1st thoracic segment, behind that a bit more of the leg on the 2nd thoracic segment, and then much more clearly both legs on the 3rd thoracic segment, which–perhaps significantly–resemble the forcipules (“poison claws”)  of centipedes. (Click on photo to enlarge)

 

You can also see on the large, 2nd thoracic segment an obvious pair of eye spots.  Remember, the head is that little thing with the Y.  Those dark spots that look to be eyes are primarily on the 1st and 2rd thoracic segments, far from the head.  Let’s turn that photo over and mark it up:

eyespots

 

All of a sudden, we have the face of a snake. (Click on photo to enlarge)

 

 

 

 

 

But coolest of all, this “snake” defends itself by striking!  Check out this video; watch what happens when I touch the prolegs.  

Despite the fact that this caterpillar is absolutely, completely, utterly, totally harmless, when it first “struck” at me, I reflexively pulled my hand away! (Sorry for the out-of-focus video–it was impossible to see what I was getting…)

Now, I ask you:  How can anyone see stuff like this and not just love insects?

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The Wonderful World of Parasitoids

 

 

Most people who have ever tried to grow tomatoes have certainly run into hornworms. These caterpillars are the larvae of hawk moths.  Strangely enough, the hornworm most commonly found on tomatoes is not the tomato hornworm, Manduca quinquemaculatus (Haworth), but the tobacco hornworm, M. sexta (L.).manduca_larva

As common and large as this pest is, many people never see (or never know they’ve seen) the adult moths.  They are nocturnal and do their very best to look like tree bark when resting during the day.manduca_sexta_adult

Tobacco hornworm larvae can get rather large: the size of an adult’s finger is not unusual.  Owing to their great camouflage, people ofter don’t even see these gigantic critters on their plants until they notice a lot of missing leaves, or they see the suddenly obvious caterpillars looking like this:

Parasitic-wasp-eggs-on-hornworm1

So what are those cute little white tufts?  No, they are not decorations the caterpillar has chosen, they are cocoons.  Each cocoon has been spun by a tiny Cotesia congregata wasp larva which hatched from an  egg laid inside this rather unfortunate hornworm.  The hundreds of eggs in each caterpillar hatch in a few days and the larvae then feed on the caterpillar from the inside for a couple of weeks, causing its ultimate demise.

This killing of the host, BTW, is the difference between a parasite and a parasitoid: a parasite feeds on another organism but does not usually threaten the host’s existence (think fleas or lice–annoying, but not inherently deadly).  Conversely, a parasitoid feeds on its host, and in so doing, kills it–this is the case with these tiny wasps.

In a move straight from Alien, the mature larvae chew their way out of the caterpillar, through its integument (“skin”), which brings us to the photo and video I took on 15 Sep 2015 when I found this caterpillar on our tomatoes.  In the photo, we can see:

  • The heads of several larvae just having chewed their way through the integument
  • Several larvae about 1/4 the way out
  • At least one larva ca. 1/2 way out
  • Fully emerged larvae
  • Larvae spinning silken cocoons
  • Cocoons already thick enough that we can no longer see the larvae within

manduca_contesia

Click on photo to enlarge it & sharpen its text

And, just for fun, here’s a video I made using my son’s microscope.  You can see a larva’s head just emerging through the integument, and next to that one, a larva busily making its silken cocoon.

When all is said and done, we shall have a very dead hornworm and a whole bunch of adult Cotesia wasps:

cotesia_adult

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