The mountains are fountains, not only of rivers, but of men. Therefore, we are all, in some sense, mountaineers, and going to the mountains is going home.
~John Muir
Back in October, Melissa and I spent a glorious ten days traveling throughout the grand state of Colorado. We didn’t have much of a plan, other than to start in Rocky Mountain National Park, and then see what else we could discover as we wandered the state. I can’t believe it has taken me this long to post something on it, but these have been busy times. One excuse was I was trying to wrap up some things before I re-retired from the NC Botanical Garden (yes, it is now official, I have worked my last day, although, to be fair, I have had the best jobs in the state over my 36+ years). I will miss the people and the place, but, it is time to see more of the wild world and I look forward to more travels, more adventures, and many more posts. Thank you for your patience.
Below is a quick pictorial summary of some of the highlights of our Colorado trip.
We lucked out and nabbed the best site in the Moraine Park Campground in Rocky Mountain National Park (click photos to enlarge)Buck mule deer next to our car one morningBear LakeNymph LakeDream LakeA small lake along the trailA great view for our lunch breakThe trail above what is the highest elevation visitor center in the National Park System, the Alpine Visitor Center, in Rocky Mountain National ParkBull elk watching his haremA coyote passing through got the elk’s attentionSpectacular views along the Tundra Communities Interpretive TrailWe saw a couple of pika at the end of the trail, dashing among the rock piles as they gathered grasses for winterOur amazing campsite along East Inlet Trail (more on this spot in the next post)Colorado National Monument was like another world, and just a half-day drive from Rocky Mountain National ParkWe saw several Desert Bighorn Sheep along the roadDevil’s Kitchen TrailA stunning Bush Katydid, Insara sp.The trail just below the visitor center at Black Canyon of the Gunnison National ParkThe Painted Wall at Black Canyon of the Gunnison National ParkOur beautiful campsite in Kebler Pass, near Crested Butte, COThe view at sunrise from our campsiteThe gold of an aspen forest in OctoberI have never seen aspen trees as big as these – it is humbling to walk through a grove of these beautiful trees this time of yearArtsy take on the aspensOrange and yellow of aspens in peak colorThe strange juxtaposition of dunes and mountains at Great Sand Dunes National ParkMelissa atop the highest dune on a very windy afternoonEarly morning at Garden of the GodsA view of distant Pike’s Peak through a rock window at the Siamese Twin formation at Garden of the Gods
Wishing all of you a wonderful holiday. Melissa and I hope to see you out somewhere in the wilds soon.
Look closely at nature. Every species is a masterpiece, exquisitely adapted to the particular environment in which it has survived. Who are we to destroy or even diminish biodiversity?
~E.O. Wilson
Yes, it is finally crawling to a close, another season of caterpillar searching, wrangling, and releasing. This one a bit less productive than some perhaps, but rewarding nonetheless. After a couple of caterpillar classes at the Museum and Botanical Garden, we ended with a bang at the Museum’s BugFest event last weekend. It was the usual phenomenal turnout with an estimated 25,000+ attendees. I am never sure how many folks we actually see at out caterpillar booth, but it was a steady stream of curious onlookers for a full 8 hours.
It was so busy this year, that I didn’t take the time to photograph some of our herd of larvae (around 50 different species). As usual, some of the best finds, like the Spun Glass Slug Moth caterpillar mentioned in an earlier post, pupated right before the big event.
This strange beauty never made it to BugFest, preferring to pupate about a week before the big event (click photos to enlarge)
We start searching a week or so ahead of BugFest, and we always lose some of our herd to the many hazards that caterpillars face – a few larvae erupted with parasitoid wasps or flies, and some we discovered as they were being used as the larval lunch special of the day for some of the many predators out there. With as many hazards as they face, it is sometime amazing we find any caterpillars at all.
While searching for clearwing moth larvae on coral honeysuckle, I came across this scene – a Florida Predatory Stinkbug with its prey
But, butterflies and moths are prolific little critters, and enough survive to keep it all going. I enjoyed watching some egg-laying behavior of several species in the week leading up to our caterpillar classes, including a snowberry clearwing (aka bumblebee moth) laying her eggs on a honeysuckle vine. I collected one egg and photographed the tiny newly hatched larva five days later.
A newly hatched Snowberry Clearwing caterpillar
The show-stoppers this year were two Imperial Moth larvae, one brown in color, the other green. Melissa found both, the brown one when it was a second instar about two weeks before BugFest. She found the green giant the day before, and I wished I could share the looks on the faces of people as they walked along the tables and first laid eyes on that behemoth.
Imperial moth larva recycling its shed skin
The rest of the critters included a wide range of caterpillars found throughout our region. As I mentioned, I took only a few minutes to quickly photograph some of the larvae before the crowds started arriving and asking questions. Here are a few more of my favorites…
The beautiful colors of a Smartweed CaterpillarEarly instar of a Blinded Sphinx (we think)A Hog Sphinx on wild grape
Though the Imperial Moth larva were crowd favorites, my choice for caterpillar of the day was the weird and wonderful Curve-lined Owlet. These bizarre-looking caterpillars feed on greenbrier and mimic the brown, curled edges of dying leaves (and perhaps the vine tendrils). They often gently wave back and forth, looking like a dead leaving moving in a breeze. When I pointed it out to people, most were stunned that it was a caterpillar, so their camouflage seems to be quite effective.
Curve-lined owlet, my choice for caterpillar of the day
The aftermath of all this larval love involves releasing the stars of the show onto their host plants from whence they came. A few that pupated will be housed in proper conditions until they emerge sometime next year, and then they will be released into favorable habitat with the hopes they will create more of their kind. Meanwhile, I may let the macro lens rest for a bit, and see if I can find something a little bigger to ponder while I wander.
If you examine a butterfly according to the laws of aerodynamics, it shouldn’t be able to fly. But the butterfly doesn’t know that, so it flies.
~Howard Schultz
I’m not sure anyone could use that quote when describing the sphinx moths. They certainly look like they were made to fly and I have always been intrigued by their streamlined shapes. Last year, I managed to photograph the green beauty known as a Pandorus Sphinx, Eumorpha pandorus. It had come to a light along our breezeway at work.
Pandorus Sphinx Moth (click photos to enlarge)
The unique wing shape, colors, and pattern are very eye-catching and make this large moth look as though someone designed it for both fashion and night-time flight.
Last week we had a chance encounter (while grilling after dark) with another of the fighter jets of the moth world. This time it was the stunning Tersa Sphinx, Xylophanes tersa. The genus name combines the Greek words xylon meaning “wood” and phanes meaning “to appear” or “appear to be.” Indeed, the wings and body of this moth look like exquisite wood veneer.
Tersa Sphinx
The larvae feed on weeds in your yard such as Madder, Poor Joe, and Virginia Buttonweed. I found one last year in our yard on Diodia teres (Poor Joe) and the caterpillar is also quite appealing to the eye.
Tersa Sphinx caterpillar
I still have a few of these moth jets I want to see (the Abbott’s, Virginia Creeper, Hydrangea, and Azalea Sphinx’s to name a few), so I’ll keep looking around lights and setting out my moth sheets every summer. I suppose my bucket list actually is a bit different than most…
I thought about not saying anything else in this post other than the quote above, because it really does sum up what we found one night this week. Yes, it is that time of year again when we caterpillar-lovers are out and about searching for something cool, something bizarre, something strange and beautiful. Melissa and I both have caterpillar programs today and then next weekend is the annual BugFest celebration at the NC Museum of Natural Sciences, where, once again, we will host a caterpillar booth. So, bear with me as I will no doubt share a few lovely larva images over the next couple of weeks.
We often find our best specimens at night, either by regular flashlight or UV flashlight (many species glow in UV light). And so it was Thursday night…some fine specimens indeed…
Black-blotched Schizura (click photos to enlarge)
The Schizura group are some of the leaf edge caterpillars – they chew out a section of leaf and then position their body within that section. The strange protuberances of the caterpillar’s body help disguise it by blending in with the jagged edges of the leaf blade.
Crowned Slug
One of my favorites, the Crowned Slug, looks like an alien creature. They, like many of the slug caterpillars, are difficult to find because they tend to feed on the undersides of tree leaves (plus, they blend in). These are best located with a UV flashlight.
The highlight of the evening was a species that I have wanted to find for several years. Being a true caterpillar nerd, I have poured over my copy of Wagner’s field guide countless times since it first came out, and been amazed at some of the bizarre larvae that can be found in our area. There are several that were on my “larval bucket list” and it is always a thrill to find one. For this species, I have seen the tiny moth a few times at home and at work, so I knew they were around.
The strange-looking Spun Glass Slug Moth
And this week, I finally found the exquisite larva (with the aid of a UV flashlight).
Spun Glass Slug
This is the last instar of this translucent little beauty. It was found underneath an oak leaf (various oaks and American beech are the host plants). It is one of the so-called stinging caterpillars (tufts of spines that can inject venom if touched). Apparently, when it gets ready to pupate, the numerous “arms” fall off.
A closer look
Of course, now I want to find some of the earlier instars. I guess it is good to have goals in your life…
Summer is a promisory note signed in June, its long days spent and gone before you know it, and due to be repaid next January.
~Hal Borland
There is a change in the air…it doesn’t seem as humid; hurricanes are in the news; and at our house, we are starting to look for caterpillars. Yes, Fall must be coming and with it, the museum’s BugFest event (and some other caterpillar-related programming at both Melissa’s work and mine). Our annual love-hate relationship with “caterpillar wrangling” is starting and will continue for the next three weeks. So, our labor for this Labor Day, was to start looking for some interesting larvae. If things run true to form, we will find a lot of really cool caterpillars in the next week or so, and then many of them will pupate before their big day (this year, BugFest is September 21…really pushing it to be able to find many of our caterpillar species still in their larval state). But, the fun is in the finding. Here are a few highlights from recent searches.
Peek-a-boo look at a last instar Spicebush Swallowtail caterpillar in it folded leaf lair (click photos to enlarge)While looking for Spicebush Swallowtail larvae, I spotted this colorful array of insect eggs on a twigIt appears as though some parasitoid wasps were first to hatch in this batch of what look like eggs of some Hemipteran bug (perhaps a stink bug)This is one is tough to identify – either a Double-lined Prominent or a Variable Oakleaf caterpillar (they can look very similar and are both quite variable)A luna moth larva just after a molt. This one is feeding on a hickory. instead of the usual SweetgumA Puss Moth caterpillar (do not touch these as they have painful “stinging” spines hidden under that “fur”). This is probably a next to last instarOne of our most common “stinging” caterpillars, the SaddlebackOne of the more bizarre-looking slug caterpillars – the Monkey SlugAn early instar Imperial Moth larva feeding on American Beech. Will it last until BugFest?A brown form of Pawpaw Sphinx on Deciduous HollyA Hog Sphinx with parasitoid wasp cocoonsThe defensive posture of a Drab Prominent on the underside of an American Sycamore leaf
You always end up getting involved in things because of, you know, the strange things your life brings you into contact with.
~Edward Norton
I have had a couple of unusual “pets” these past few months. You may recall in an earlier post, I reported on receiving some orphaned Eastern Hercules Beetle grubs one day at work.
Eastern Hercules Beetle grubs (click photos to enlarge)
A woman brought them in after they were discovered in the hollow of a large tree she had taken down in her yard. She wasn’t sure what they were, but hoped someone at the Garden could tell her and might take them. The front desk volunteer apparently thought, Hmmm, who here would want something like this?…Oh, Mike, he probably would. And that is how I came to have two large grubs in a flower pot of rotten log and topsoil on our screen porch since late March. They are pretty easy pets to take care of – I checked them once or twice a week, spritzing the soil surface each time with a little water to prevent them from drying out. A few times over the summer, I refreshed their rotten log food supply with decayed wood and a couple of apple slices. On several occasions, I showed them to a few house guests (we have tolerant friends) and to visitors during some programs at work. The last time I did this was about two weeks ago for a group of summer camp kids. To do this, I gently poured the soil out into another bucket to reveal the grubs. On the last pour, I noticed one of the grubs had made what looked like a chamber in the soil (it was an impression in the soil about the size of a large chicken egg). I should have known what was about to happen, but it didn’t register at the time.
This past Sunday afternoon, I went out to once again spritz them with water, and when I lifted the lid off the bucket, I was amazed (and a little startled at first) at what I saw…
The alien on our porch, the pupa of an Eastern Hercules Beetle
…and it moved! It’s alive! One of the grubs transformed into a bizarre-looking pupa. This will become a male beetle, as evidenced by the horns, which apparently are quite fragile in the pupal stage. The impression I had seen in the soil a couple of weeks ago was the start of a pupation chamber. The larvae make these one to two weeks prior to pupating. I was probably lucky that my disturbance of the soil had not disrupted this transformation.
The reference I bought talked about this delicate life stage, but did not give information on how long the pupa stage lasts. Another web search found a site that summarized the life stages of the Eastern Hercules Beetle (from the University of Kentucky Critter Files on Eastern Hercules Beetles):
Adult longevity: Typically 3-6 months. The rare adult will live up to a year plus.
Egg-laying to egg hatch: 1 month
Egg hatch to pupation: 12-18 months
Pupation to emergence: 2-3 months, depending on temperature
Emergence of teneral adults to fully-formed adults: About 1 month
I am amazed at the life span of these amazing insects. It looks like I will have these pupae until December or so, when they will emerge as adult beetles. But, they apparently remain in the soil for a month or more while they harden their exoskeleton and change to the adult coloration. Stay tuned. I really want to have one of these giant beetles (with about a 6-inch wing span) flying around the house one day next spring:)
Children should be encouraged to watch patiently and quietly, until they learn something of the habits and history of bee, ant, wasp, spider, hairy caterpillar, dragon-fly, and whatever of larger growth comes in their way.
~Charlotte Mason
Summer camp at work has been over for a week now. The decks of our building are quiet, the classroom cleaned up, the debris in my office waiting for me to find it a home. My role was largely to assist with the field outings, helping to share the excitement of whatever cool stuff we encountered. I suppose it’s a good role given that I get almost as excited as they do over any living thing, large or small. I took my camera on all the outings, and it soon became a frequently heard shout, “Mr. Mike, look what I found, take a picture”. So, every day, I would take a few photos on our hikes, and print some of the best out to share with them after lunch. These “run-n-gun” photos aren’t meant to be works of art, but rather a glimpse into the incredible diversity that we can all find on a short walk in nature, especially if we have the curiosity (and energy) of a child. Here are a few of the highlights from our nature walks (I think we covered most of those mentioned in the quote above)…
One young camper had a talent for catching almost anything from lizards to skippers. He ran towards me one day with this juvenile Carolina Anole, saying, “Mr. Mike, it’s eating a moth”. Just as I snapped a photo, it gulped down its meal, oblivious to all the commotion (click photos to enlarge)We witnessed a lot of the “cycle of life” these past two weeks. Here a Bumblebee Mimic Robberfly has captured a bumblebee.Another view of robberfly and bee – you can see some differences in the mimic and the model here – the robberfly has short antennae and very different eye structureGreen Lynx spiders are now large enough to easily see in the wildflowers, where they prey heavily on pollinators, including wasps and beesAnother Green Lynx with a fly. These active hunters do not build webs for capturing their prey, but instead pounce on them like a large catPerhaps a nymph of one of the Spiny Assassin Bugs?We had a lot of critters land on us during camp. This jumping spider (Hentzia sp.?) picked one of our more squeamish instructors to hitch a ride on.An ant dragging a dead wasp. One camper told me “ants are the strongest animals in the world and they can carry over 10 times their own weight”. I googled it and found that ants are, indeed, incredibly strong and are believed to be able to carry 10-50 times their own weight (equivalent to a human lifting ~9000 pounds). Their body structure and movement are being studied by engineers in the hopes of designing powerful microbots to perform all sorts of tasks. Who is teaching who in this camp?Hackberry Emperor butterflies frequently perch on humans to imbibe our salts (sweat)Our visit to the vernal pool in the woods yielded a variety of newly transformed amphibians. Eastern Narrow-mouthed toads, actually tiny toad-like frogs, were everywhere along the edge of the pool.Fowler’s Toad toadlets were also commonA very tiny Cope’s Gray Treefrog (note the diagnostic white patch under they eye)This American Dagger Moth caterpillar provided a lesson in being a naturalist and observing the world around you. I found some frass (insect poop) on the trail. After helping them figure out what it was, I asked the campers where to look for the caterpillar that made it. After a couple of guesses in all directions, one camper figured it out and pointed up. We brought it into the classroom to observe for a few days before releasing it back into the wild. The campers named this hairy caterpillar, “prickly pear”.We all witnessed an amazing act – a female Dobsonfly laying her egg case on the wall outside the classroom (it took over an hour). Unfortunately, the hatchlings will not fall into a suitable aquatic habitat when they emerge.A short-horned grasshopper nymphA newly emerged damselfly with exuvia on an emergent stem of Pickerelweed
Tremendous beauty can be found in the tiniest of things… for who has ever thought to rival that of a butterfly’s wing.
~Kristen D’Angelo
Close up of hind wings of an Eastern Tiger Swallowtail (click on photos to enlarge)
Every few years, we have a population high of swallowtails here in our woods. This year has been exceptional with the greatest numbers of these large butterflies that I have witnessed. This is especially true of our largest (and one of the most recognizable butterfly species) the Eastern Tiger Swallowtail (Papilio glaucus). One reason they are so common for us is that our woods are dominated by one of their primary host plants, Tulip Poplar.
We have a relatively small area that receives enough sunlight to grow wildflowers, and this time of year the primary nectar sources are Joe-Pye-Weed, Ironweed, and Garden Phlox. When I walked up to the house one afternoon a week ago, it reminded me of being inside a butterfly house, with large butterflies drifting all around me and seemingly covering every available flower head. I decided to estimate their abundance, so I went inside and started counting swallowtails visible from the front window and the kitchen window. I was stunned when I finished with a total of 90 swallowtail butterflies! Most were Eastern Tiger Swallowtails, but there were about 6 Spicebush Swallowtails as well.
Joe-Pye-Weed has been the favorite nectar source in our yard – this one flower stem has 6 swallowtails on it (one is hidden on the back side)
I did a quick Google search looking for explanations of these population highs and lows in tiger swallowtails. I discovered that what I am witnessing both here and at work is also being seen this summer up and down the East Coast – an explosive population year for Eastern Tiger Swallowtails. But, my searching yielded no real clues as to why. It seems there are just too many variables to explain these population swings, although most scientists agree that it probably relates to weather conditions that negatively influence populations of the abundant predators, parasitoids, and fungi that prey upon the pre-adult life stages of these butterflies.
The Garden Phlox has been the big draw for butterflies at work (NC Botanical Garden), especially this one patch (there are 7 swallowtails scattered in this photo, but I have seen many more at times)
Whatever the reason, it has been an incredible summer for swallowtails. They are believed to live an average of 3 to 4 weeks as adults, so they are starting to decline a little after a peak a couple of weeks ago.
Below is an introduction to the swallowtails (and one look-alike) that frequent our woodland garden. The next time you venture out, look closely at your butterflies and see which ones are most common in your landscape.
Female Eastern Tiger Swallowtails have more blue on their hind wings than males.Males may have a little blue in the hind wings, but not nearly as much as females.And, just to make it more confusing, female eastern Tiger Swallowtails can also be blackish in their wing background coloration. You can often see faint traces of yellow in the wings, especially from the underside. Like our other black-colored swallowtails, this is believed to mimic the unpalatable Pipevine Swallowtails. The black color morphs are generally more abundant in the mountains, where Pipevine Swallowtails are also more common.Spicebush Swallowtails (Papilio troilus) are recognized by the wash of color on the hind wings. Females have bluish color and male a bluish-green color. Their host plants are Sassafras and Spicebush. They are generally more active as feeders, flapping their wings much more than Eastern Tiger Swallowtails.I don’t see many Black Swallowtails in our yard as they are more of an edge species. There are plenty at work, especially late in the summer, due to the abundance of one of the host plants, Golden Alexander. They are smaller than Eastern Tiger Swallowtails and tend to have a bold yellow stripe (males). Females look similar to black morph Eastern Tiger females, but they are smaller and the orange spot at the base of the hind wings has a dark spot in the center.One day I looked out and saw a very active swallowtail with yellow under its wings feeding on the Joe-Pye-Weed. I recognized it as a Giant Swallowtail (Papilio cresphontes).Ironically, it was almost exactly a year ago that I saw my first Giant Swallowtail in Chatham County. They are large (North America’s largest butterfly) and very active butterflies, making a spread wing shot somewhat difficult.Pipevine Swallowtail (Battus philenor). Males (photo above) have a brilliant iridescent blue-green color on the hind wings. Females are duller. This species is an irregular visitor to our yard but is easily recognized by its fluttering feeding styles compared to most other swallowtails. Spicebush swallowtails are also active feeders, but appear much larger than Pipevines. As caterpillars, this species sequesters toxins from their host plants (pipevine and Virginia Snakeroot) which are transferred to the adult, giving them some protection from hungry birds and other predators.My favorite butterfly, the Zebra Swallowtail (Eurytides marcellus). These beauties are found in areas near their host plant, pawpaw. Freshly emerged specimens often have hints of blue on their wings.Often mistaken for one of our four dark-colored swallowtails, the beautiful Red-spotted Purple (Limenitis arthemis astyanax) is believed to be another mimic of the unpalatable Pipevine Swallowtail. It has iridescent blue hind wings, lacks the wing tails, and has blue dashes or spots along the wing margins. This species is very common in our woods where its host plant, Black Cherry, is abundant.Many butterflies are now showing signs of aging and the hazards of life in the wild. This male Eastern Tiger Swallowtail is missing part of one hind wing, perhaps a victim of a missed attack by a bird or mantis.Birds are major predators of the larval stages of butterflies, but I have not seen much depredation on adult butterflies, especially of our larger swallowtail species. On two occasions, we have seen flycatchers like Eastern Wood-peewees and this Great Crested Flycatcher snag a butterfly in flight.Large Robberflies are reaching their peak population about now and I have seen them hit some of the swallowtails that were nectaring at flowers, but have only seen one actually carry a large butterfly off to feed on it. This one has a large Carpenter Bee as its meal.Large spiders (large orb weavers) are major predators of swallowtails in our yard. I do see the butterflies occasionally escape once they hit a web, but we also see many wrapped in silk in the many webs that dot or yard.Another important predator of large butterflies are the praying mantids, especially the introduced Chinese Mantis. They wait near flower heads and lunge and grab the butterflies. They must be difficult to see as I have watched butterflies forage on the same flower that has a mantis feeding on one of their cousins.
I’ve always preferred moths to butterflies. They aren’t flashy or cocky; they mind their own business and just try to blend in with their surroundings and live their lives.
~Kayla Krantz
National Moth Week ended yesterday and I managed to miss most of it for a variety of lame reasons. But, even though I failed to put out my moth light (which is at work for summer camp use), I did manage to find some cool moths hanging out at lights or ones I flushed from their hiding place as I went about my work. With your permission, I’m going to cheat a little and present a few that I photographed outside the official moth week window. The group includes several that are new to me and several that meant more because I have photographed their larval forms in the past. So, get outside and look around, the beauty and variety of moths is astounding!
I found several large sphinx moths (most sphinx larvae are known as hornworms due to a prominent tail spike). They are the fighter jets in the moth world, typically with a sleek shape and rapid flight.
Plebian sphinx, Paratrea plebeja(also known as the trumpet vine sphinx) (click photos to enlarge)Pawpaw sphinx, Dolba hyloeusRustic sphinx, Manduca rustica
It was also a good week for the underwings, so named because they tend to have bright colors on their hind wings that are only revealed when they open their forewings (this may serve as a predator avoidance aid when flashed).
Clouded underwing, Catocala nebulosaIlia underwing, Catocala ilia (also known as Beloved underwing or Wife underwing – photographed on tree trunk to show their wonderful camouflage)Penitent underwing, Catocala piatrixSaddled prominent moth, Heterocampa guttivitta
It was a good week for little green moths…
Red-fringed emerald, Nemoria bistriariaRed-bordered emerald, Nemoria lixariaBad-wing moth, Dyspteris abortivaria (love this name) Spun glass slug moth, Isochaetes beutenmuelleri (I really want to find this one’s caterpillar – look it up and you’ll see why) Ailanthus webworm moth, Atteva aurea, a colorful day-flying moth, often seen pollinating various wildflowersRosy maple moth, Dryocampa rubicunda, one of our most beautiful, and common, mothsGray-banded OR Oblique zale, Zale sp.Brown-shaded gray, Iridopsis defectariaMaple zale moth, Zale galbanataPlain Plume Moth, Hellinsia homodactylus (the plume moths are among the strangest looking moths!)
The biggest surprise was a rather innocuous-looking little moth found outside one of the entryways to the office. As is often the case, a close-up image showed some beautiful patterns and subtle colors that I might have otherwise missed. But the shocker came when I identified it and saw its name – Wasp Parasitizer. That’s right, this little moth lays its eggs on paper wasp nests and its larvae consume the larvae and pupae of the wasps! The natural world, literally just outside our doors, is truly amazing.
Ants are everywhere, but only occasionally noticed. They run much of the terrestrial world as the premier soil turners, channelers of energy, dominatrices of the insect fauna…
~Bert Holldobler
The more I learn about them, the more I appreciate plants. Working at the NC Botanical Garden allows me to see the passage of time through the eyes of a variety of native plant species. I have witnessed slow, long-term seasonal changes, as well as brief glimpses of wonder. And so it was that last Friday when a coworker came in right before closing and showed me her phone video of ants dispersing the seeds of a trillium in the Herb Garden. It was amazing to see them carrying such a huge load across the rocks. I grabbed my camera and headed over, hoping I wasn’t too late.
An ant carrying a Trillium seed back to its nest (click photos to enlarge)
I have seen this phenomenon, called myrmecochory (seed dispersal by ants), a few times before and reported on it in an earlier post. Estimates are that 30%-40% of our spring-blooming woodland flowers rely on ants for seed dispersal. Another source stated that elaiosomes occur in over 11,000 plant species! There are various theories as to why ants do this and how it benefits the seeds:
the lipid-rich appendage is a food reward that is fed to the ant larvae when it is taken back to the nest
the seed is dispersed away from the parent plant, which may provide a better growth environment by reducing parent-offspring or sibling competition
by quickly transporting the seed to its nest, the ants’ behavior reduces the time the seed may be exposed to various seed predators (the seed might get eaten by a bird or mouse, for example)
when the seed is discarded into the ant “trash pile”, it is in a nutrient-rich environment ideal for germination
In addition, one author speculates there may be some benefit from the anti-microbial properties within ant nests that will reduce the susceptibility of the seed to various pathogens.
Studies where a researcher has removed some of the elaiosomes and compared removal rates have shown that ants remove seeds with elaiosomes more quickly, often using the appendage as a handle.
But the most intriguing research I have seen focuses on the reason the ants pick up the seed in the first place. It seems that elaiosomes rich in oleic acid trigger a stereotyped carrying behavior in a variety of ants. E.O. Wilson, the dean of ant researchers, showed that a dead ant starts emitting oleic acid about 48 hours after its death. This is a signal to other ants to pick it up and carry it back to the nest and discard it. He even added a drop of the “dead ant” acid to a live ant, which was quickly picked up and carried to the trash pile, in spite of its thrashing and obviously living qualities. To quote an NPR story on this experiment, Dead is what you smell — not what you see — if you are an ant. So, do plants mimic an insect chemical in order to get ants to carry out their seed dispersal tasks? It appears there may also be some benefit to the ants in this relationship, but the origins of this behavior are fascinating to ponder.
Below is a series of images depicting about 45 minutes in the long life story of one wildflower – a plant that may take 2 years for its seed to germinate, and then another 5 or 6 years to flower and produce its first seed. And, it seems to have figured out a way to con a bunch of insects (yellow jackets are also known to disperse seed with elaiosomes) to carry its seeds back to their trash pile. There appears to be a lot going on out there in the woods that we are just beginning to understand. All the more reason to plant some native plants and get outside and observe your wild neighbors.
The source of the seeds – Little Sweet Betsy, Trillium cuneatum (this photo was taken in another location in the garden back on March)This is how the Trillium that provided the seeds looks now (this photo was taken a couple of days after the ant dispersal images and the seed pod has now disappeared)The seed pod was lying on a leaf and was laden with antsA peek inside at the seeds with elaiosomes and antsAn ant lugs a seed up and out of the podThen it is easy-going downhill on a leafThen on to a lichen- and moss-covered rockThe first hazard on the journey – the steep drop-off of the front edge of the rock (as I watched, a fewants fell off this ledge with their heavy loads)A feast when a few seeds fell out onto the rockThe elaiosome provides a good grip for an ant’s jawsThe path taken by the ants – about 6 feet across an open walkway to the rock in the backgroundAn ant with its prize just before disappearing into the nest beneath the leaf litter
Roads End Naturalist 