Predator Satiation

Polistes carolina/perplexus with Magicicada prey | Shaw Nature Reserve, Missouri

I’ve probably used the term predator satiation more often during the past couple of weeks than I have during the entire rest of my life.  Students of ecology know this as an antipredator adaptation in which prey occur at such high population densities that they overwhelm predator populations.¹  This ‘safety in numbers’ strategy reduces the probability that any given individual will be consumed, thereby ensuring that enough individuals survive to reproduce.  With St. Louis currently experiencing the appearance of Brood XIX of periodical cicadas, I’ve gotten lots of questions recently from many coworkers and friends wanting to know more about these cicadas.   Often the first question is “What is their purpose?”  My standard reply begins with a statement that they, like all living organisms, are the products of natural selection, which then presents an opportunity to explain how natural selection might result in such massive, temporally synchronized, multiple-species populations.  A few eyes have glazed over, but I think most have found my answer interesting, often even leading to further questions about where they lay their eggs, what is their life cycle, why are they so loud, how do they “do it” and select mates, etc.  Of course, as an entomologist with a strong natural history orientation, I’m always anxious to introduce people to ecological concepts, and right now the periodical cicada is providing a conspicuous, real-life example of such.

¹ Also called “predator saturation,” although this term might be misconstrued to mean that it is the predators that are over-abundant.

First the eyes...

A few weeks ago, right at the beginning of their emergence in the St. Louis area, my friend Rich Thoma and I observed predator satiation in action.  While hiking one of the trails at Shaw Nature Reserve, we heard the unmistakable shriek and cellophane-sounding wing flapping of a just-captured male cicada.  Tussling on the ground ahead of us was the cicada in the grasp of a Polistes carolina/perplexus wasp, which was repeatedly stinging the hapless cicada on the underside of the abdomen.  The shrieking and wing-flapping grew less frequent as the stinging continued, until at last the cicada lay quiet.  As we approached, the wasp spooked and flew off, but we knew it would be back—we parked ourselves in place while I setup the camera, and before long the wasp returned.  It took several minutes of searching from the air and on the ground before the wasp finally relocated her prey, but once she did she began voraciously devouring it.  As the wasp was searching, we hypothesized that our presence had altered the visual cues she had memorized when flying off, resulting in some confusion when she returned, and thus the long period of time required to relocate her prey.

...then the legs!

We watched for awhile—first the eyes were consumed, then the legs.  As it consumed its prey, Rich remarked that he bet he could pick up the wasp and not get stung—likely the entirety of its venom load had been pumped into the cicada.  Both of us declined to test his hypothesis.  We also wondered if the wasp would butcher the cicada after consuming part of it and bring the remaining pieces back to the nest.  We had seen a European hornet do this once with a band-winged grasshopper, consuming the head, then cutting off the legs from the thorax and flying away with it before returning to collect the abdomen as well.  No butchering took place this time, however, the wasp seemed content to continue eating as much of the cicada as possible—a satiated predator if there ever was one!

Leg after leg is consumed.

One eye and all six legs down, time to start on the abdomen.

Copyright © Ted C. MacRae 2011

Brazil Bugs #2

A few more photographs from this past week in Campinas, Brazil.  It rained during the afternoon but stopped by the time I arrived back at the hotel, allowing me to stroll the lavishly landscaped grounds during the mild evening hours.  There is a pink-flowered shrub forming a hedge row in back of the hotel that is highly attractive to many types of insects.  The identity of the shrub remains a mystery to me, and most of the insects I’m finding on it I can recognize only to family – I’m hoping the hotel staff will be able to name the former and that the readers of this blog might be able to provide IDs for the latter.

Calycopis sp. poss. origo (Lepidoptera: Lycaenidae). ID by Dave Hubble and Chris Grinter.

It took a bit of effort to find an unobstructed view of this hairstreak butterfly (family Lycaenidae) as it visited the flowers within the shrub.  Every time I tried to move foliage out of the way to get a good view, the butterfly became alarmed and flew to another part of the hedge row.  My antics drew the attention of a hotel worker, who was apparently interested enough in what I was doing to act as a spotter whenever the butterfly flew to help me relocate it.  Eventually I got a few shots that I was happy with, including the above.

A flesh fly (Diptera: Sarcophagidae).

I presume this to be a type of flesh fly (family Sarcophagidae) based on the stout bristles and color pattern that seems typical for the family.  I like the striking contrast in coloration between the fly and the flower.  There are a few fly bloggers who I’m hoping might be able to give a better identification.

A potter/mason wasp? (Hymenoptera: Vespidae).

This appears to me to be some kind of potter or mason wasp (family Vespidae, subfamily Eumeninae) – it was a bit smallish at only about 12mm in length.  I hope one of the knowledgeable wasp bloggers out there (ahem… Eric?) can at least confirm this level of identification and perhaps the tribe or genus as well. 

Azya orbigera (Coleoptera: Coccinellidae). ID by Tucker Lancaster.

Every ladybird beetle (family Coccinellidae) I’ve ever seen is some variation of black and red/orange/yellow and has a smooth, glabrous appearance.  This beetle is cobalt blue with a dense pubescence over the dorsal surface, but it still seems to me to be some type of ladybird beetle.  It was a tiny little thing, so I suppose it could be one of the multitude of small beetle families with which I am unfamiliar.

Quedas sp.? (Hemiptera: Cicadidae).

This cast cicada exuvium was not on the shrub, but on a nearby tree at about eye level.  I really wish I could have seen the cicada that emerged from it, because this is certainly the biggest cicada exuvium I have ever seen.  I was about to simply label it “family Cicadidae” but seem to recall that cicada higher classification is in a bit of flux these days.  At any rate, given its great size I wonder if it might represent one of the giant cicadas in the genus Quesada.

I still have many more insect photographs from the past week and will certainly increase that number over the next week as well.  Stay tuned!

Copyright © Ted C. MacRae 2011

Guest Blogger: Dogbane for Dinner

Our guest blogger for today is Anne McCormack. I have known Anne (or known of her) for more than 25 years now, first as a long-time editor of Nature Notes, the journal of the Webster Groves Nature Study Society, and more recently on a personal basis as I, myself, have followed in her editorial footsteps. Anne is an astute naturalist whose breadth of knowledge spans not only botany but also entomology and ornithology, all of which she write about in her own blog at Gardening with Binoculars.


I planted Common Dogbane (Apocynum cannibinum) because some of my butterfly-watching friends reported numbers of juniper hairstreak butterflies on the patch of dogbane at Powder Valley Nature Center in Kirkwood. I assumed incorrectly that dogbane was a host plant for hairstreaks, and believing it to be little more than caterpillar food, I placed it in a hot, dry, narrow strip along the driveway. Ragged, caterpillar-chewed leaves wouldn’t be noticed there, and I forgot about it. After a few seasons, it was still a modest-sized clump, but the leaves were in great shape. In fact, it had grown into an attractive bush of airy, elegant lime-green foliage, wine-red stems, and tiny white flowers. It’s quite a contrast to its relative, Common Milkweed, growing next to it, which looks as if it were designed by Dr. Seuss—even before it gets chewed to bits. At this point I decided it was time to look it up and see why it had failed to support hordes of munching caterpillars. As you have already guessed, gentle reader, the Juniper Hairstreak’s host plant is juniper, not dogbane, but good old Common Dogbane is a great nectar plant. Now that Dogbane and I understand each other better, I can appreciate the amount of traffic its tiny white blooms bring in, like this Peck’s Skipper butterfly. Ants, butterflies, tiny native bees, honeybees, and this mason wasp are busy there all day long.

Along with several species of moth, it is the host plant for the Dogbane Beetle, which spends its larval stage devouring the roots and its adulthood dining on the leaves of Dogbane, and nothing but Dogbane. Dogbane Beetle can be confused with Japanese Beetle by beginners like myself, but unlike its fellow Coleopteran, Dogbane Beetle is harmless. That makes its iridescence all the more gorgeous, as shown in this wonderful photo by Courtnay Janiak. It’s a native insect that has shared a long evolutionary history with this under-appreciated native plant. American Indians valued it for its bark, which is tough but peels off in long strips. They plaited it for bowstrings and anything that called for twine; hence, its other common name, Indian Hemp. Don and Lillian Stokes, in their 2002 PBS show about bird watching, demonstrated how birds seek out the dry stems of this perennial, pulling off strips for nests in early spring. Nesting material can be hard to come by for birds in the tidy suburbs, so I don’t clean up the stems after frost. “Bane” in the name refers to the toxin cymarin in the plant’s leaves, though the plant would have to be covered in braunschweiger before my dog would be interested. Edgar Denison, in Missouri Wildflowers, translates the genus name Apocynum as “away dog.” The species name cannibinum refers to hemp. Its seedpods remind me of French green beans. These split at the end of the season, and the seeds fly away on fibers similar to milkweed seeds. Collect some and try this plant in your butterfly or native plant garden. Give it a spot where it’s easy to watch the colorful visitors.

Dogbane beetle (Chrysochus auratus) - Copyright © Courtnay Janiak

Copyright © Anne McCormack 2010

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Circus of the Spineless #47

When I started participating in blog carnivals last year, Circus of the Spineless was – for me – the pinnacle of blog carnivals.  I wanted to take my shot at hosting this venerable celebration of creepy crawlies, and even though the waiting list for hosting was almost a year long, I offered my services and settled in for the long wait until February 2010.  Ten months have passed and the time has come.  In the meantime, I did my blog carnival host début with Berry Go Round #21 and snatched the sophomore slot for nature blogging’s newest carnival with House of Herps #2.  Through those efforts, I learned that blog carnival hosting is an incredible amount of work/fun, and while plants and herps are fascinating, inverts are my true love.  It is, thus, with great pride that I join the ranks of previous hosts in presenting this, the 47th edition of CotS.  Featured below are 16 submissions by 14 contributors that cover representatives from 5 classes in 3 invertebrate phyla.  A humorous look at some of the personalities behind invertebrate study is presented as a bonus for those who make it to the end.

If you missed last month’s issue, you can find Circus of the Spineless #46 at Kate’s Adventures of a Free Range Urban Primate, and next month’s edition will be hosted by Matt Sarver at The Modern Naturalist.

Phylum CNIDARIA
–Class ANTHOZOA

Coral Reefs
The Voltage GateJeremy at The Voltage Gate reports on peer-reviewed research on the impact of herbivorous fish on the recovery of coral reefs in his post, Protecting herbivorous fishes significantly increases rate of coral recovery.  Coral reefs have been hard hit by the challenges of bleaching and disease, pressures likely linked to climate change, and macroalgae, when given the opportunity to dominate, provide even further challenges.  This can happen when populations of herbivorous fish, major grazers of macroalgae, are reduced through commercial harvest.  The study authors evaluated ten sites over a two-and-a-half year period in and around the Exuma Cays Land and Sea Park (ECLSP), which was established as a no-take marine reserve in 1986, finding an increase of coral cover during the study period from 7 percent to 19 percent.  However, ECLSP reefs were responsible for all of this increase, with no net recovery occurring outside the ECLSP.  These results illustrate the importance of reserves as a refuge for biodiversity and the service they provide in keeping marine systems intact.

Phylum MOLLUSCA
–Class GASTROPODA¹
—-“Informal Group” OPISTHOBRANCHIA

Sea slug (Glaucus atlanticus)
Deep-Sea NewsThis gorgeous nudibranch species got a foul slandering when they started washing up on Gold Coast beaches in Australia.  Miriam Goldstein debunks this unfair treatment in her post, Sea slugs have self esteem too, at Deep-Sea News, noting its absolutely stunning iridescent blue and silver color with gorgeous feathery tentacles.  Further exception is taken with such descriptors as “slimy”, “venomous”, “blue-bottle eating”, and “cannibals” – with the truth behind each of these terms far more fascinating than the visceral reaction their use was intended to elicit.  Good news as well – you don’t have to travel to Australia to see these things – they live throughout the world’s open oceans (but you will have to get far from shore, where the pelagic jellys upon which they feed can be found).

—-“Informal Group” PULMONATA

Iron-clad snail (Cyrsomallon squamiferum)
Deep-Sea NewsI’ve known about iron-clad beetles, species of Zopheridae whose exoskeleton is so hard and thick it is almost impossible to impale them with an insect pin.  I’d never heard of an iron-clad snail, however, until I read Dr. M’s post, The Evolution of Iron-Clad Samurai Snails With Gold Feet, at Deep-Sea News.  Unlike the seemingly iron-impregnated beetles, these snails actually utilize iron sulfide in a series of armor plates covering the “foot.”  Just described in 2003 from a hydrothermal vent in the Indian Ocean, it is the only known animal known to use iron sulfide as skeletal material.  Only time will tell if these snails achieve the same popularity as living jewelry as the beetles.

¹ The taxonomy of the Gastropoda is under constant revision, as the results of DNA studies increasingly reveal as possibly polyphyletic many of the former orders (including the Opisthobranchia and Pulmonata, now known as “informal groups”).

Phylum ARTHROPODA
–Class CRUSTACEA
—-Order DECAPODA

Samurai crab (Heikea japonica)
ArthropodaMike Bok at Arthopoda shares two stories about this crab – one an ancient Japanese legend, the other a modern piece of scientific folklore – in his post, Samurai Crabs: Transmogrified Japanese warriors, the product of artificial selection, or pareidolia?  In the first, popular legend alleges that these crabs were transformed from drowned samurai warriors, each one identifiable by the face of the fallen samurai that it bears on its backs and for whom the crab searches in the depths of the oceans around Japan.  This ancient legend has led to a modern scientific quibble about whether the stylized face that can be seen on the crab’s carapace is the result of artificial selection by generations of superstitious Japanese fishermen, who have selectively released crabs bearing any resemblance to a human face.  This may make for compelling scientific debate, but Mike counters even the considerable eloquence of Carl Sagan in providing his own thoughts on why this likely is not true.

—-Order AMPHIPODA

Amphipod (Phronima spp.)
ArthropodaIn another example of the intermixture of science and culture, Mike Bok (Arthopoda) asks, Did Phronima inspire the design of the Alien Queen?  Mike agrees with the claim that the original “soldier” alien morph seen in “Alien” (1979) was based on a painting by artist H. R. Giger, but he thinks that Phronima more likely influenced the design of the queen alien morph in “Aliens” (1986).  The truth may remain hidden at Stan Winston Studios, but the broad crest atop the head of Phronima, bearing tubular, upward-pointing eyes, its “necro-parasitic” tendencies, and a chillingly suggestive photograph of the beast from a 1981 paper lend an air of plausibility to Mike’s hypothesis.

–Class ARACHNIDA
—-Order PHALANGIDA

Harvestmen, daddy-long-legs
Kind of CuriousJohn at Kind of Curious follows up on David Attenborough’s Life in the Undergrowth Episode 1 with his post, Daddy Long Legs Daddies (aka Harvestman).  Looking like spiders but lacking their venomous and silk-spinning abilities, it seems that nobody can agree on the proper name for these spider relatives.  Brits call them “harvestmen”, but Americans call them “daddy-long-legs”, a term that in the UK refers rather to crane flies (which less informed Americans simply call “giant mosquitoes”).  Let’s not even mention the daddy-long-legs spider (Pholcus phalangioides), which actually is a spider.

—-Order ARANEA

Neoscona crucifera (barn spider)
XenogereAnyone who hikes along woodland trails in the eastern U.S. during autumn knows what a “spider stick” is – i.e., any handy stick that can be waved probingly in front of one as they hike, lest they run smack into the web of any number of orb weavers that are fond of stretching their large webs across such natural insect flyways. Jason, at Xenogere, has some biggun’s in his neck of the woods, which he describes in intriguing detail in his post, Walking with spiders – Part 3. Barn spiders are some of the biggest, allowing one to fully appreciate their polychroism and polymorphism. I challenge even the most arachnophic of readers to look at Jason’s photographs and not be mesmerized by their beauty.

–Class INSECTA
—-Order ODONATA

Autumn meadowhawk dragonfly (Sympetrum vicinum)
Rambling Woods~The Road Less TraveledMichelle at Rambling Woods~The Road Less Traveled presents a stunning series of photographs of this gorgeous red dragonfly in her post, Circus of The Spineless~Curiosity will conquer fear even more than bravery will.~James Stephens.  Perching on her hanging basket of pink-flowered begonias, colors matching perfectly, it was almost as if the dragonfly has staked a claim on the hanging basket as it own personal territory.  Where there is one, there are others, and her neighbor’s deck had both a red male and a blue female doing… well, see Michelle’s diagram.

—-Order COLEOPTERA

Horned passalus (Odontotaenius disjunctus)
Anybody Seen My Focus?Joan Knapp at Anybody Seen My Focus?  shows photographs of this beetle in her post, Bess Beetle: Horned Passalus (Odontotaenius disjunctus), as it lumbered slowly and gracefully over a fallen tree branch.  Perhaps the cool temperatures were the reason for its sloth.  Or perhaps the missing antenna indicated a feeble, old individual on its last (six) legs.  A brief interruption for photographs seemed not to deter the beetle from its destination, somewhere in the leaf litter beyond the log…

—-Order LEPIDOPTERA

Skipper butterflies (family Hesperiidae)
Nature of a ManRandomtruth at Nature of a Man loves skippers (are they butterflies, or aren’t they?), and you’ll love his photographs of these delightful little half-butterflies in his post, Day Skippers.  While there is some slight doubt about the identity of individuals he sees in his backyard (skippers are notoriously difficult to identify in the field), there is no doubt that these little guys are loaded with personality.  You won’t believe the “natural history” moment he caught on film (er… pixels?) and presented in the final photo sequence.

Monarch butterfly (Danaus plexippus)
GrrlscientistGrrlscientist summarizes a recent peer-reviewed paper in her post, Migratory Monarch Butterflies ‘See’ Earth’s GeoMagnetic Field.  The paper reports on photoreceptor proteins in monarch butterflies known as “cryptochromes” that not only allow the butterflies to see ultraviolet light, but also allows them to sense the Earth’s geomagnetic field.  These highly conserved proteins evolved from the light-activated bacterial enzyme phytolase, which functions in DNA damage repair.  Most animals have one of two types of cryptochromes, but monarchs have both – providing the first genetic evidence that the vertebrate-version of cryptochrome is responsible for the magnetoreception capabilities in migratory birds.  Further research may provide insight on the workings of the circadian clock, which could lead to better understanding of sleep disorders and mental illnesses such as depression and seasonal affective disorder, as well as development of new treatments for jet lag and shift-work ailments.

—-Order HYMENOPTERA

Ants (family Formicidae)
Wild About AntsKatydids, grasshoppers, cicadas – what do ants have on these singers of the insect world?  Plenty, as Roberta at Wild About Ants points out in her post, Ants: No Longer the Strong Silent Types.  It turns out that ants have patches of ridge-like structures on their gaster, which they rub against a curved ridge (called a “scraper”) on the petiole to communicate with each other via stridulation.  While lacking the decibel level of a cicada, these sounds are nevertheless in the audible range for human ears and are thought to have alarm, mating, and recruitment functions.  Even more fascinating, stridulation is not the only tool in the ant music chest – drumming and rattling have also been documented.  Curiously, however, ants do not possess ears, rather likely sensing sounds through their legs or by specialized hairs on their antennae.  Check out the provided links to SEM photographs and a sound recording.

Bald-faced hornet (Dolichovespula maculata)
Hill-Stead's Nature BlogDiane Tucker, Estate Naturalist at the Hill-Stead Museum in Farmington, Connecticut, writes at Hill-Stead’s Nature Blog. In her post, Be it ever so humble, she takes a look at some of the different animal nests that become revealed during autumn’s leaf drop – particularly those made by the bald-faced hornet (and also birds such as oriole’s).  From its start as simple cluster of chambers, to its growth over the course of the summer – growing fatter until the summer’s apex of warmth and light, then tapering off with the approach of fall, these insect homes are a marvel of nature – intricately constructed homes made entirely of paper.

—-Order DIPTERA

Common green bottle fly (Lucilia sericata)
Bug Girl's BlogBug Girl discusses the resurging use of bottle fly larvae in her post, Maggot therapy.  The academic among us will appreciate her discussion of the mechanisms that allow these seemingly disgusting vermin to function as incredibly delicate microsurge0ns in cleaning and disinfecting open wounds.  The morbid among us will appreciate the links to the most entertainingly disgusting medical photos one can imagine.  Check it out – but not over your lunch hour!

BUGS IN FIR

Wanderin' Weeta (With Waterfowl and Weeds)Wanderin’ Weeta (With Waterfowl and Weeds) was going to make an owl out of Douglas fir cones, but instead she found globular springtails, a crab spider, and a ladybug in a sprig of fir.  We’re glad she has an interest in little hitchhikers such as these, even if the kids at school when she was growing up didn’t.

ENTOMOLOGY HUMOR

Bug Girl shows that entomologists have a sense of humor with her post, Monday Morning bug jokes – a video compilation of jokesters from the recent Entomological Society of America Annual Meeting in Indianapolis.  My favorites were the best dung beetle pickup line (“Is this stool taken?”) and Marvin Harris’ rendition of the minimum number of insects needed to elicit control (1 pubic louse, or 1/2 codling moth larva :)).  J. McPherson was equally, if unwittingly, hilarious due to his Christopher Lloyd-esque mannerisms.  My favorite entomological joke of all, however, was not featured, so I offer the following addendum to Bug Girl’s post:

Copyright Ted C. MacRae 2010

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