Hattie's Scarab

Hattie's Scarab

I received this photograph from our friend Courtney who found the insect with her 3 year old assistant Hattie. They sent it in to INaturalist and got a tentative ID of Bolbocerosoma bruneri. That would put it in the Geotrupidae family, the Earth-Boring Scarab Beetles, EBSB, (also called dung beetles). 

B. bruneri - Marci Hess cc

I would agree with the genus Bolbocerosoma but have reservations on the species. All the photographs of B. bruneri on Bugguide show a thin curved black line on the thorax immediately behind the head which is missing in the picture above, so I am going to stick to Bolbocerosoma sp which gives us 12 species to choose from in the US.  They all have in common the orange pronotum, black markings and five deep punctuate grooves on their elytra.

EBSB with its mound - Ag.Purdue.edu

EBSB have a very interesting life cycle. They burrow tunnels into the ground, some up to 9 feet deep. They may have multiple chambers at the bottom and the opening on top frequently has a pile up of dirt like a miniature prairie dog mound.  They deposit an egg at the bottom and then food above it forming a plug. This can include collected feces, decaying plant material, and fungus. The adults do not care for their young.  When grown, the grub will pupate, the adult emerges and climbs to the surface to fly off, probably relieved to be out in the fresh air.

They soon however return to the same old diet, eating decaying material and fungus and  and are often found on dung piles or compost heaps. Adults come to light which probably explains the one on Courtney's porch. Once you get past the "yuck" factor, remember that they are an earth-friendly species, similar to a vulture in recycling carbon and nitrogen from dead and decaying material into the soil. You didn't have any other plans for that dung, did you?

Life in a Walnut Husk

We were collecting walnuts to make walnut ink when I discovered life living under the husk.  It turns out that the space between the nut and the rind is a busy place.  These little wigglers might have given the normal observer a bad case of the heebie-jeebies but they only piqued my curiosity.  These are the larvae of the walnut husk fly (WHF), Rhagoletis completa.

Husk fly eggs in groups of up to 15 are deposited under the outer husk surface and hatch after five days into little white maggots. Older maggots turn yellow with black mouthparts.  The maggots feed inside the husk, gradually turning the husk mushy and black. After feeding for a month, the maggots drop to the ground and burrow into the soil where they will spend the winter as pupae.

Walnut husk fly - wsu.edu

"The adult is about 1/4 inch (6 mm) long, slightly smaller than a housefly. It has large, iridescent, greenish eyes, a tawny  brown body color and banded wings. It has a yellow spot on its back. Its conspicuous wing markings make it easy to identify. The female is larger than the male and its abdomen is more pointed." Washington State University also has  more information on WHF.

Husk fly male - Don Loarie

WHF gets no respect on the internet.  The maggots' feeding discolors the nut shells and makes the husks hard to remove. Early summer husk fly infestations also can stunt nut kernel development.  They can occasionally attack nearby apricot and peach tree fruit.  Most references are to methods of killing them and preventing the spread to commercial walnut crops.  A number of tactics are described to combat them including use of Sevin and malathion, which can affect a wide variety of innocent insects.




Damaged walnut husks laying on the ground may host other insects.  I have found other insects and tiny spiders hiding inside damaged husks and on a WOLF field trip while looking for husk fly larvae we found this tiny winged creature pictured here which I couldn't identify.

I recently found some other even more mysterious critters, but you will have to wait for them in another blog.  Speaking of tiny creatures, A Chaos of Delight has hooked me on "mesofauna" - photographs and stories of the wide variety of 0.1 mm to 2mm creatures living in soil.  It is addictive so enter at your own risk.

Tiny Mushroom

Someone asked me if I hunt and I answered "no", then stopped to think about it.  I do hunt but it is for interesting plants and insects.  Birders "hunt" birds and many mycologists hunt mushrooms, neither group intending to eat their prey.  Here is Mark Bower's description of a September "hunt."

"I had been walking in the woods for 2 1/2 hours looking for mushrooms to photograph. The woods were dry, and I had only taken one picture all morning. As I was leaving the woods, I noticed two small mushrooms growing together on a moss-covered log. I assumed that they were just the usual boring brown-capped Pluteus species which are very common, and not worth stopping for. On closer inspection, however, I noticed the scaly appearance of the cap, which would be very unusual for Pluteus.

Spore print

This prompted me to get on my knees and closely inspect it. To my surprise, the stem appeared to be streaked with purple. Multiple photographs were taken and a spore print revealed pinkish spores. With this information, and after reviewing my books, using keys, etc., I had no clue. I then put the info on the MOMS Facebook page. The genus Entoloma was suggested as a possibility.

The color of the spores is one of the distinguishing traits used to identify mushrooms. There are a lot of ways to make a spore print but the basic method is placing the underside of the cap on a surface and keeping it moist to encourage the spores to drop.  It helps to have a dark and light surface to contrast against the spores which may vary between white or pink to dark brown.  

I then posted it on Mushroom Observer, which is a website which is reviewed by mycologists, like Bugguide for Fun-guys and gals.  My boring little mushrooms were identified as Entoloma tjallingiorum, and even though I can’t pronounce the name, I’m very happy to have found it.  Half the fun is in the hunt while identifying them is like cleaning the game.  And stop asking "are they edible?"

Fuzz on the Kale

Braconid pupae from kale - REK

My editor (wife Barb) keeps me constantly entertained with her discoveries in the garden.  This time it was clusters of tiny fuzzy spots stuck on the underside of lots of our kale leaves.  The whole cluster measured only an eighth of an inch, a jumble of oblong fuzz balls.  We put the leaf fragment in a plastic box and left it on the dining table for a few days.*  

Braconid Wasps - REK

When we next checked it there were tiny 2mm black specks on the lid.  When I opened it, they immediately flew out.  The next day there were more and this time the box went in to the freezer for a few hours before opening it. These turned out to be tiny wasps.

I sent the pictures to Bugguide.net and got a rapid response from Ken Wolgemuth.  He identified them as braconid wasps (Braconidae) in the subfamily Microgastrinae.  He explained that these are "individual cocoons that were spun by the wasp larvae that were consuming the host (e.g. caterpillar) that was feeding on your kale. They then emerged from these cocoons as the adult wasps you are seeing now."

Braconid wasp - 2mm   REK

The Braconidae family of wasps numbers over 17,000 species and counting.  They are parasitic like their larger Ichneumonoidea wasp cousins, using the larvae of beetles, flies, butterflies and even aphids to feed their young.  Once they crawl out, they spin their cocoons for protection until they emerge as adult wasps.

We think of having a virus as a disease but for Braconid wasps polydnaviruses are their nannies.  The wasps carry polydnaviruses which they have coevolved with over thousands of years.  These are injected into a host caterpillar along with their eggs.  The viruses are harmless to the wasp but immediately start to disable the host's immune defenses against the foreign eggs.  The wasp eggs hatch, develop into larvae and feed inside the host until they emerge and form the pupae we found above.  The wasps soon emerge and begin the cycle again with their friendly virus still on board.**

Cabbage white - Bob Moul

These clusters were really good news.  We have lots of cabbage white butterflies (CWB),  Pieris rapae, constantly hovering around the kale.  They are the most common butterfly in North America, an unwelcome European import which arrived around 1860 and is now on every continent on the globe except Antarctica.  They are a hearty breed, the first to emerge in the spring, flying from March through November.  In addition, their reproductive success comes from the fact that they may have 7-8 hatches a year and the wide range of host plants they can raise their young on.

Cabbage white caterpillar - Wikipedia- CC

On close inspections any of you gardeners may find one of these innocent looking caterpillars.  CWB lay one egg on each available leaf of their host plant. They eat predominately plants in the mustard family, (Brassicaceae) including cabbage, broccoli, and our kale as well as dandelion, red clover, asters, and mints.  They seem especially addicted to our leafy garden plants, chewing holes in the kale leaves until they look like  sieves. 

Cabbage white pupa - Bob Moul

The pupae of the cabbage whites are green or brown with points on the ends, resembling a dried up leaf. The last batch of caterpillars hibernate over the winter as chrysalids and hatch into adult butterflies in the spring ready to start the cycle again.  We have learned to embrace these little fuzzy spots on the kale leaves, wishing them great reproductive success as they munch away on the innards of the invasive caterpillars.

We can almost forgive them for occasionally attacking caterpillars we raise at the Butterfly House.  For a graphic example of Brachnoidae larvae emerging from horn worms, check this Youtube video.

*  Note: I am blessed with a wife that will tolerate road kill snakes and a found blue heron skulls in her freezer.  Since she accepts them, what problem is a little plastic Gerber baby food box containing insects sitting beside the salad bowl?
**  Braconid wasps and Polydnavirus

Ghost of Bull Mills

Shed hunting is a popular non-violent winter sport in the Ozarks.  After the fall rut, a buck's need for a bragging rack is gone for the year.  Decreasing testosterone levels lead to reabsorption of the bone at the antler base and eventual shedding, leaving the antlers on the forest floor.  Soon squirrels and wood rats find them and use them for sharpening and shortening their constantly growing incisors and obtaining calcium...unless Barb finds them first.  Barb is the family shed hunter and she found this beautiful pair on January 2008.


This pair ended up on our stone fireplace, tied with leather thongs as the center of the display.  They remained there until the Spirit of the Great Buck returned 10 years later.  Last Tuesday I came into the creek house and found them on the floor with the leather thong neatly sliced in the middle.  Wood rats, aka pack rats, Neotoma floridana, are frequent guests and we hear the click of a trap several times a year so I wasn't concerned and tied them back on the wall.

Here is where it gets a little weird.  Three days later we were eating dinner at 8PM right beside the wall when they came clattering down to the floor.  We hadn't seen or heard any varmit activity and the thong appeared to be cleanly cut.  Spooky!  The next morning I rubbed Siracha jalapeno sauce on the thongs, tied the cut ends together and hung them back up.  I hoped the lip burn of capsicum would dissuade a rat.

The following night at the same time we were eating when they came crashing down again!  Again the cut thong looked clean and no scurrying mammals were in sight.  I went to bed with the image of the Spirit of the Great Buck attacking me at night with an antler.

Gnawed, scissor and knife cut.

The next morning in the cold light of day the fear passed.  Under magnification I compared the cut end of the thong with scissor and knife cuts.  The end was ragged compared to the others, obviously gnawed cleanly in half without the assistance of a ghost.  At least that is what we were telling ourselves.

I hung them again, this time with the thongs tied to copper wire which was looped over the nail.  We returned 18 hours later to find one antler back down on the floor with a chewed thong.  I tied it up again and after sitting on the porch working for an hour I returned to the house and found it cut back down again!  (You can't make stuff like this up!)

This time I put up a game camera on the post opposite the antlers, hoping to catch the culprit digitally.  The next morning the antlers were safe and there was a rat in a trap.  The rat had committed suicide in our rat trap rather than be filmed doing its dastardly deed again.  The antlers have now remained in place after three weeks.

Case closed (we think), but if we don't make the next meeting, who ya gonna call?  Ghost Busters!
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And for a pleasant bedtime read to take your mind off that scary tale I would highly recommend this entertaining description of the interaction of termites farming fungus, or is it the fungus that farms the termites?

Red-shouldered Bugs

Our Springfield neighbor Cyrus asked me to identify these bugs that were covering his privacy fence.  These are nymphs of the red-shouldered bug (RSB) or jadera bug, Jadera haematoloma.  The interesting question is what are they doing here in our neighborhood?

RSB distribution - soapberrybug.org

RSB are members of the soapberry bug subfamily, Serinethinae.  There are 65 hemiptera species in the family and interest in their their evolution and adaptation to human associated changes on the planet has earned them their own webpage, Soapberry Bugs of the World.   

The sudden spread of these new species is due to adaptive radiation, "the diversification of a group of organisms into forms filling different ecological niches."  Darwin's finches evolving different beaks to adapt to varied food sources are a prime example of adaptive radiation.  For the soapberry bug family, their success is based on their evolving ability to tolerate the cyanide defenses of the soapberry plant.
 
Bugguide says RSB occur year-round in CA, TX, and FL, with peak numbers in May in central Florida but they are also found in southern Missouri and Kansas. Their native host plants are Sapindaceae family plants and the western soapberry, Sapindus drummondii, is a native species found in a few southern Missouri counties. 

Adults mating - Rebekah D. Wallace

The red-shouldered bug moniker is obvious when you see the adult.  It averages 1/2 inch long.  Most pictures of adults show them mating, either because that is what they do most of the time or that is how to find them holding still for a photograph.  They can be a nuisance like box elder bugs when they invade your home and can also stain children's clothes red when they play in an infested yard.


I think the key to why Cyrus found his fences covered with RSB nymphs lies across the street in a neighbor's goldenrain tree.  This is Koelreuteria paniculata, a native of China and Korea imported to the USA in 1763 and now a popular landscape tree worldwide.  (Editor's confession: we had one once in our back yard.)  In some areas the RSB are observed feeding so often on goldenrain tree seeds, Koelreuteria spp. (Sapindaceae), that they are referred to as goldenrain tree bugs.

Mosquito Bite Update

After posting this blog with photographs of a mosquito biting my arm in the middle of the afternoon, I had it identified on Bugguide as the eastern tree hole mosquito (ETM), Ochlerotatus triseriatus.  This turns out to be an unusual insect.

Although it does breed in moist holes in trees, it really specializes in tires, tires stored or trashed on the ground.  If you have ever tried to get all the water out of a tire on a creek cleanup, you know that it is a definition of forever.  This has become an important urban mosquito because of tire dumps and scrap yards around cities where there can be 60,000 mosquitoes per acre in the summer.

Eastern tree hole mosquito - Ilona

Asian tiger mosquito

At first glance to my untrained eye ETM looks a lot like the Asian tiger mosquito.  The differences are more obvious to an entomologist but include the abdomen which is mainly dark scaled with only the margins of the last four segments with pale patches, and legs that lack the white spots of the Asian tiger mosquito.

"Few mosquito species feed rodents. These mammals are just too jittery and quick to sit still for that. But Ochlerotatus triseriatus, even though it bites a wide variety of mammals, including humans and sometimes birds, particularly likes chipmunks and squirrels. These woodland rodents are active during the day when Ochlerotatus triseriatus is seeking hosts in the woods."  Bugguide

We are unlikely to see these during the evening when mosquitoes are abundant.  They tend to occur during the day, as mine was, when their mammal hosts are active.  The ETM transmits La Crosse encephalitis virus, an uncommon but significant disease.  While 70% of females hatching from infected eggs inherit the virus, the good news is that it isn't that common in most of its range.  There are around 72 cases per year in the US and it usually affects children.  If it only would transmit the disease to the wood rats in our house!

Tracking Pollution

Ozarks Water Watch

David Casaletto published this article on the Ozarks Water Watch newsletter and let me share it on the blog. 
==========================
Bacterial Source Tracking Needed to Determine Pollution Contributors
David Casaletto, Executive Director, Ozarks Water Watch.

I was attending a conference this summer and a presentation on Bacterial Source Tracking (BST) really got my attention.  In more laymen terms, a laboratory identifies the source of the E.coli and other bacteria that are polluting our streams and water bodies.  What really made me sit up and listen was, according to this study in Texas, 62% of the bacteria came from wildlife, while 10% was human and 13% cattle.  These were not the percentages I expected!


In Texas, there are 273 bacterially impaired water bodies.  With a nonpoint source grant, they set out to identify and assess the sources of these bacteria - E. coli, Enterococcus, fecal coliforms - in these water bodies to properly determine the risk to water recreation.  Then they would develop effective watershed restoration strategies, such as watershed protection plans (WPPs) and total maximum daily loads (TMDLs).

Bacterial sources are extensive and include all birds, wildlife, livestock, pets and humans.  Source surveys, computer models and bacterial source tracking (BST) are the primary methods for identifying predominant bacterial sources in impaired waters.  BST offers distinct advantages over computer modeling and source surveys.

Source surveys, which estimate the numbers and distributions of animals and humans in a watershed, are not capable of assessing most wildlife species or how bacteria from sources are transported to the impaired waters.  Computer modeling addresses the issues with transport; however, because wildlife populations are rarely known, models are unable to adequately assess contributions from wildlife.  BST is able to evaluate wildlife, along with other major sources, and the impacts of transport because BST uses instream water samples for its assessment.

The premise behind BST is that DNA fingerprinting and other molecular targets can identify bacterial strains specific to each animal species since each species has different diets and digestive system conditions that select for distinct strains of bacteria.  This distinction allows the original source of the fecal contamination to be identified.  But BST methods require the development of a DNA fingerprint library.


The Texas BST Library currently contains more than 1,500 E. coli isolates obtained from more than 1,300 different domestic sewage, wildlife, livestock and pet fecal samples.  These isolates, which represent more than 50 animal subclasses, were selected after screening several thousand isolates from more than a dozen different studies throughout Texas.

BST accuracy is best when identifying broad source categories and decreases as the sources are more specifically identified.  A 7-way (non-avian wildlife, avian wildlife, pets, cattle, other non-avian livestock, avian livestock, human) categorization is shown in chart to the right.



The technologies used for BST are continuously evolving and improving. BST has been tremendously helpful in identifying significant bacterial sources throughout Texas.  The state BST laboratories can provide guidance and assistance with performing BST for watersheds. I think it is time for other states to jump on the BST bandwagon.  Too many times, we "think" we know the source of the pollution is human or CAFO, when it may be wildlife.  More information on BST can be found at: texasbst.tamu.edu.
_______________________________________________________________

Ozarks Water Watch is a non-profit organization dedicated to maintaining and improving the water quality of the upper White River watershed.
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Wee Tiny Ladybug

 
I picked a little fleck off my pant leg and it crawled up onto my thumb for a picture.  It looked like a lady beetle but it seemed too small.  Through the wonders of INaturalist, it came up as the number one choice, a twenty-spotted lady beetle (TLB) Psyllobora vigintimaculata.  Another common name is "wee tiny ladybug."  At 2-3mm long, I thought they would rarely be "spotted" (sorry!) but I found 9 pages of their photographs on Bugguide.

 
Psyllobora sp. are called fungus-eating lady beetles.  P. vigintimaculata (Latin for twenty spotted) feeds on powdery mildew that occurs on leaves from ground level to tree tops. They scrape up fungal spores with mandibles armed with rake-like rows of small teeth.

"Fungi, we have lift-off!"  Oliver Burris CC

TLB are found in all states including Alaska and the the first specimen to be described was in Missouri!  They come in a variety of colors with a white to tan background.  The color can be variable, based partially on the region they are found in, but they all have in common placement of their spots. Like all "ladybugs" they are beetles in the family Coccinellidae.  The majority of this family feed on plant eating insects that are unpopular with gardeners such as aphids and scale insects.  Although we think of them crawling around they are capable of flight after lifting their heavy wing covers. Ten years ago identifying species like this required an extensive knowledge of entomology and would be left to the species specialists or an extensive search of old reference books.  Now sites with photo recognition such as INaturalist.org allow quick comparisons and expert entomologists share their time identifying photographs on Bugguide.  What a great time to become a nature nerd!

Tiny Oak Galls

Zopheroteras guttatum with a ballpoint pen

Collecting pin oak, Quercus palustris, leaves for a school project, I felt a tiny hard bump on one. Under magnification it was a perfectly spherical 2mm gall that looked like a piece of candy.  The usual sources couldn't identify it, but I got a rapid response from a submission to Bugguide.  This is a gall of a cynipid wasp, Zopheroteras guttatum.

Zopheroteras guttatum - eol.org

Galls catch our eye with lots of pictures but the insects that build them get little respect.  In this case I did come up with pictures of a Z. guttatum adult from the Smithsonian on Eol.org.  Three pages of Google searches yielded only other photographs of galls, most of which were confirmed by Charley Eisman, the guru of galls.  

Eisman's describes  Z. guttatum galls in more detail.  "Causes spherical, 1.45-2.5 mm galls, with purple spots, single on a secondary vein on underside of Quercus palustris, imbricaria,
or texana leaf, in fall."  Initial descriptions
specified the underside of the leaf but there are
now other examples of the same galls on the
upper side.

I went back to the tree looking for more of these galls but found only other leaf galls.  These fuzzy oak leaf galls are far more common, produced by Callirhytis furva,  They are said to drop from the leaves in October but I more commonly find them attached to a fallen dried leaf on the ground.  Again, EOL provided a photo of the cynipid wasp that makes the gall.

Callirhytis furva - Eol.org CC

I haven't had any success in raising the wasp from a gall but I may have given up too soon.  Weld who wrote the book says they emerge "in the second or third spring in late March."  Typically a cynipid wasp would mate and then lay eggs on a leaf, in these cases a red oak.  The mere fact that these 2-3mm wasps would find each other to mate after a 3 year gestation is hard to fathom but "love finds a way,"

Like the spiny oak galls

Hard dried galls - REK

we wrote about in the past, the hatchling that emerges from the egg creates damage on the leaf which responds by growing around it, creating a shelter and food source until it is ready to emerge.  What I find fascinating is the many different ways that the leaf responds, each distinctive for the specific species.  I found a few other less distinctive galls on Cyrus's pin oak,  including one below that had delivered its young.

Empty gall - REK

Each of these galls are now in clear plastic boxes, trying my wife's patience as they fill the closet.  I know she will be excited to know that I now need to keep them for three years.

Hammerhead "Slug"

Worm measuring over 3 WGPBC units

Our friend Pat found this while walking her dog.  It left a slime trail in the morning light and she had the forethought to photograph it with her friend Erin's snack pack for a size comparison.  Converting WGPBC units, (Whole Grain Peanut Butter Crackers) to inches (5.2") we can say the critter is over 7.3" long!

Her story is a great example of how an untrained naturalist approached the unknown.

"It almost looked like a small snake with a dark stripe down center back and lighter stripes on either side of that. It had a ginkgo leaf shaped ‘head’ and seemed to be de-scaling the curb like a snail as it crept along. It also moved differently than your standard worm.  When we looped by the area again on our walk the live one had its tail smashed and succumbed to its injury. I did collect the dried out dead specimen, don’t ask me why.

I saw another one a few days later that was at least 12 inches long, and the flat half-moon ‘head’ was proportionally larger as well.  After the sightings last week I Googled ‘worm-like slug’ and got an immediate hit on Hammerhead Slug.   The site I viewed did not describe them as being in this area, but it sure looked like what I was seeing."

The Hammerhead Slug, aka. Greenhouse Planarian (Bipalium kewense, BK) is the "Worlds Largest Flatworm" and one of the few flatworm species that live on land.  It is unrelated to slugs which are in a totally different phylum, but it leaves a slime trail like slugs and snails do.  It was probably originally an Asian species that has been imported along with potted plants.  It occurs throughout the southern US as well as world wide.  Pat's is the first one reported in Missouri on Inaturalist.org.

Bipalium kewense capturing an earthworm  -Pierre Gros

Here is a description of the feeding process.

"The flatworm initiates here the process of ‘capping’ the anterior end of the earthworm. Observed reactions of the prey suggest that it is at this stage that the planarian secretes a toxin to reduce prey mobility. The planarian also produces secretions from its headplate and body that adhere it to the prey, despite often sudden violent movements of the latter during this stage of capture. Pierre Gros.

Posterior fragment

Although all Bipalium sp.  are hemaphroditic, their usual reproduction is by asexual fragmentation.  They attach their tail to the ground, then pull it off to leave the segment to move on its own.  Over the next few weeks it regenerates a head and pharynx and becomes a fully functional if somewhat shortened adult.  Fun fact in bad taste: Its pharynx is also its anus!

BK feeds primarily on earthworms which it tracks down, then pins down by its slime.   It also produces a neurotoxin (tetrodotoxin) that results in paralysis that may help it mobilize the worm.  Dinner spoiler alert!  Then its pharynx spreads out and releases an enzyme that partially digests the worm outside its body.  Later the same pharynx will evacuate its waste.  You can watch it attack a worm in this video although you may want to mute the sound.

The BK produces very little toxin and it is not harmful to humans or their pets.  One source says it is a pest for farmers because it kills worms but it is hard to imagine there are enough of them to be a problem.  I am thinking it might make a nice pet for a Nature Nerd.  Pat, are you game?
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Much more detailed information on Bipalium kewense can be found at  this Wikipedia link and Entnemdept.ufl.edu.

Monarch Parasitoid Tachinid Flies

Tonya Smith, MN, told me about her recent experiences with monarch motherhood and Tachinid fly parasites and I asked her to share her story and photographs on the blog.

Tachinid Fly Parasites on Monarchs

Tonya Smith

Monarch chrysalis with signs of a parasitoid - Tonya Smith

Success, free at last

One of the many wonders of nature is the metamorphosis of the butterfly. I learned the basics in school, but now I was successfully raising one monarch caterpillar observing the process first hand. I was hooked ... on butterflies! From my training for being a docent at Bill Roston Butterfly House, I learned less than 5% of butterflies reach their adult stage. Of course, the good news is our planet would be defoliated if we didn’t have the checks and balances in nature to control the ravenous caterpillars in the Lepidoptera order which includes moths and butterflies.

Fast forward several weeks from my first experience raising a monarch caterpillar and it’s release. The swamp milkweed in my perennial garden had an abundance of the famous black, yellow and white striped caterpillars.  My morning and evening “cat walks” became a regular occurrence, hoping to observe the ones that were leaving to pupate so I could watch over the chrysalids.  I noticed many small caterpillars leaving the host plant possibly because it was over populated so I took some young instars in to finish raising them.

Cat with a strings attached

Soon the horror show got underway. Caterpillars got into what appeared to be a healthy “J” position, but time would prove their bodies were parasitized. The caterpillars became limp and out came the tachinid fly larvae on gelatinous tendrils that look like white strings. In some cases, the caterpillar successfully formed the beautiful green chrysalis. But excitement turned to disappointment once the chrysalis became discolored and holes appeared for the tachinid fly larvae to exit. The success rate of the ones I was raising was zero percent.This scenario was replayed in my yard as I saw caterpillars and chrysalids hanging from the soffit or brick that had succumbed to the tachinid fly.

Tachinid eggs - Gord Harrison

So here was the living proof of nature’s checks and balances. Tachinid flies belong to the Diptera order and are in the Tachinidae family.  Their larvae are internal parasites of immature beetles, butterflies, moths, sawflies, earwigs, grasshoppers, or true bugs. The adult fly may lay its egg on a host species or penetrate it to place the egg inside.  The fly may even lay her eggs on plants where the maggots can be ingested by the future host after they emerge.

First look outside with more to come

Once inside, the maggots begin to consume the hosts by eating non-essential tissue first which allows the host to continue to grow and feed normally. Only when this material is fully consumed, will the larvae turn to eating vital organs. It’s in the tachinid larvae’s best interest to allow their host to live as long as possible so they can grow fast. The larvae then pupate into adults inside or emerge to pupate outside the prey’s body as seen in my monarch's video. For a real world replay of The Blob, see my video.

Three in a chrysalis

Leaving home

Karen Oberhauser is an Associate Professor in the Dept. of Fisheries, Wildlife and Conservation Biology at the University of Minnesota. She and her student, Michelle Prysby, started the Monarch Larva Monitoring Project in 1996 which studied the reproductive ecology, host-parasite interactions, and factors affecting the distribution and abundance of immature monarch stages. Their research showed that the species Lespesia archippivora is the most important monarch tachinid parasitoid. It is widespread throughout North and Central America, has been found in Brazil, and was purposely introduced into Hawaii for biocontrol in 1898. More details are at Monarchlab.org.

Oberhauser's report titled, Tachinid Flies and Monarch Butterflies: Citizen Scientists Document Parasitism Patterns over Broad Spatial and Temporal Scales (author Karen Oberhauser), cites an approximate 92% mortality during the egg and early larval stages from other natural enemies than the tachinid fly. In a study where volunteers collected and reared monarchs in all immature stages, they found from one to twelve flies emerged from individual monarchs. Later stages tended to produce more flies per monarch when comparing the 1st-3rd to the 4th-5th instars. So monarchs collected during the later stages were more likely to be parasitized and the daily risk of parasitism was higher during the middle three stages. This of course is why it is recommended to raise monarchs from the egg stage. So eventually my “cat” walks turned into a search for those that needed to be euthanized after observing the signs indicating larvae were using our beloved monarchs as their host body.

Larva on the move

"Which way to a pupation station?"

An article in American Butterflies reports on a study of fly parasitism across North America which found up to 30% of monarchs die from parasitoid attack in some regions and years, with up to 10 fly maggots emerging from a single monarch pupa. These high rates of parasitism suggest that tachinid flies could be a major factor regulating wild monarch populations. When Butterflies get Bugs: The ABCs of Lepidopteran Disease.

While many of us curse the tachinid fly, there are those who welcome and attract these parasitic insects and for good reason. On an agriculture level, they help control major crop pests including cabbage worms, Gypsy moth, Colorado potato beetles, corn ear worms, cucumber beetles, cutworms, earwigs, four lined plant bugs, Japanese beetles, Mexican bean beetles, sawfly larvae, squash bugs, and tobacco budworms. In fact, one Organic Farmstand and Education Center in Vermont states, “Never destroy caterpillars with white eggs on their backs as these will develop into more tachinid flies.” So for those of you with vegetable gardens, provide tachinid flies with a diversity of plants with small flowers including flowering herbs, and plants in the Aster family. Cedarcirclefarm.org
 

Tachinid pupa

Tachinid fly emerged

There are several viral and bacterial pathogens that can infect monarchs, including a nuclear polyhedrosis virus and Pseudomonas bacteria (Brewer and Thomas 1966, Urquhart 1987). Protozoan parasites such as Ophryocystis elektroscirrha and a microsporidian Nosema species have also been identified in wild and captive monarchs. Much work and effort is invested in helping the monarchs. Besides the destruction of habitat and climate changes, I realize it is a great tug-of-war between natural predators and human intervention to improve the monarch population. Monarch Parasites and Natural Enemies

You can review all of my tachinid fly photographs in this Flickr album.
Meanwhile, I prefer to end on a positive and happy note with a short video (here on Youtube) of a monarch that beat the odds and hopefully is one of many hibernating in Mexico this winter."