Monday, September 25, 2017

Tiny Hover Fly


We were talking with friends when a few visitors buzzed us and finally landed, waiting patiently for their portraits.  I recognized them as a type of hover fly, aka syrphid or flower fly, but couldn't ID them initially.  BugGuide quickly identified them as Toxomerus politus.

Jacsun and his fly
Hover flies get their name from the way they hover in front of flowers while nectaring.  To the uninitiated, and presumably to predators, they look dangerous with colors suggesting a miniature yellowjacket.  These aposematic colors of yellow and black are common among some of the Syrphids but these are harmless flies that couldn't hurt a human.  
T. politus and their larvae (aka maggots) likely feed on corn pollen, and herein lies the puzzle.  We are a long way from a corn plant, likely 3+ miles and 300 feet altitude up to the Prairie View plateau.  Yet, here there are several of these flies looking fat and sassy.
 
vena
Wikipedia mentions that "with a few exceptions, hoverflies are distinguished from other flies by a spurious vein, located parallel to the fourth longitudinal wing vein."  They show in the illustration on the left.  Out of curiosity, I zoomed in on one of our T. politus and sure enough, there it was.

Syrphid flies as a class are important contributors to our ecosystem.  Many species are pollinators and some species have larvae that are predatory, eating aphids in large numbers, potential agents of biological control.

Like the news bee which we recently wrote about, this and other hover flies seem to have an attraction to humans, visiting and sometimes even landing on us.  Try to appreciate them and hold your impulse to swat.
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Way more information that we need on T. politus is available at this Syrphidae Community Website.

Saturday, September 23, 2017

One Smooth Turtle


My third grade colleague Bruno grabbed this little 2" long turtle from a still segment of Bull Creek.  Its "shell" was smooth and almost flexible like leather.  I initially thought it was a midland smooth softshell, Apalone mutica mutica, based on illustrations in Missouri Turtles.  I sent it on to Brian Edmond who thinks it is a cousin, the eastern spiny softshell, Apalone spinifera.

This is one thin turtle.  This is probably a benefit when laying on the bottom, waiting for a tasty aquatic insect or crayfish to pass by.  Their young are susceptible to predators such as raccoons and herons while the adults only have to worry about humans looking for a source of turtle soup.*  They are said to have a painful bite.

A. spinifera is identified by small bumps on the edges of its carapace, seen below just behind the head.  The placement of the spines can help define the multiple subspecies, a fine detail only important to taxonomists and presumably to the turtles.  "What lovely tubercles you have my dear.  Care to go for a swim?"  With luck it is the beginning of a brief affair.

Deb and the turtle- She is the one in the back- by Chris Barnhart
Mating is almost a Victorian affair.  It occurs when they are 6-8 years old, no big rush here.  In the spring the male swims up to the female and nudges her head.  If she turns up her nose at him it doesn't matter as his nose is turned up as well.  If she accepts, he swims above and fertilizes without grabbing or holding on.  Several months later she will dig a cavity in a gravel bar and cover up her 8-30 eggs and from then on they are on their own.  They will hatch in September or even the following spring.

A. spinifera are said to mate in deep water, but without any deep pools along our stretch they must have to take their chances in the shallows.  There is no hurry as a large female (up to 19") may live for 50 years, and they are safe from us except for an occasional hungry human.
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* Limits and regulations of soft shelled turtles are at this MDC site.  The limit on our section of Bull Creek is zero!

Animaldiversity.org has more details on the species.



Sunday, September 17, 2017

Walnut Sphinx Moth

Walnut Sphinx Moth - REK
Over the last several weeks I have photographed many different moths coming to our Bull Creek deck light.  My favorite wasn't one of the showy giant silk moths but this more humble walnut sphinx moth, Amorpha juglandis.  The picture above is its usual resting position that I had been seeing several every night.

The female moth emerges from its cocoon and spreads its wings to dry.  It also spreads its pheromone over the air to attract a male.  Once fertilized she will fly off to lay 200-300 eggs on an appropriate food plant.  Her caterpillars will eat the leaves of a variety of trees including butternut, hazelnut, hickory, hop-hornbeam, and of course, walnuts. Like the giant silk moths, they have no intestine and live less than a week.

 Walnut sphinx caterpillar with its horn -  MJ Hatfield CC
Like other moths, the caterpillars serve as a food source for lots of spiders, birds and insects.  A dramatic example is the walnut sphinx caterpillar parasitized below.  Chris Barnhart found it on a dried up leaf and we identified it by the color and its distinctive "horn" at the end of its abdomen.

Parasitoid cocoons on a dead walnut sphinx moth caterpillar - REK
The most likely parasitoid is a Braconidae. The female lays eggs on the caterpillar and the young burrow into the caterpillar which continues on with life, chewing leaves happily while the young grow in its body.  Eventually they make cocoons and the caterpillar's health fails.  They are careful to avoid killing the caterpillar until they are full grown and ready to emerge.
"Most life histories involve parasitizing hosts as diverse as aphids, bark beetles, and foliage-feeding caterpillars. Many species are egg-larval parasitoids, laying eggs within host eggs and then not developing until the host is in the larval stage. Unlike ichneumon wasps, many pupate in silken cocoons outside the body of the host and others spin cocoons entirely apart from the host.(3) Also unlike ichneumonid wasps, very few braconids use host pupae to complete their life cycles, except for fly parasitoids in Alysiinae and Opiinae." from Bugguide
Empty cocoons - click to enlarge
Unfortunately we found this one when they had all left their cocoons.  I kept it in a sealed box in case there was one left but had no luck, just like the poor caterpillar.

The sphinx moth itself is a cool creature which is able to whistle at a high pitch, out of our hearing range but heard by birds. We wrote a blog about this some years back.  The sound comes out of the most distal spiracle and I wonder if that may be why it holds its rear end up.  On the other hand, it may just be showing off.

Monday, September 11, 2017

One Cool Toad


My third grade colleague, Bruno, is a great hunting companion.  Curious, quick and built low to the ground, he is now feared by every amphibian and lizard along Bull Creek.  He caught three small toads over an hour within fifty feet of our house, not to mention a number of 3" skinks.  The little toad above was different from any I had seen before so I sent it off to Brian Edmonds who responded rapidly that it is a dwarf American toad.
"Dwarf American toads are confined more or less to the Ozarks. They are smaller than other American toads and are often reddish in coloration. The red spots are diagnostic."
Our "garden variety" toad along Bull Creek is the American toad, Anaxyrus americanus.  It turns out there are three subspecies.  The eastern American toad, Anaxyrus americanus americanus, is the one we all know and love, warts and all.
"The eastern American toad is medium-sized and has a large, kidney-shaped gland called the parotoid gland behind each eye. The pupil of each eye is horizontal. This toad may be gray, greenish gray, or various shades of brown. The dark spots on the back may encircle 1–3 warts. The belly is white with dark gray mottling. The call is a sustained, high-pitched musical trill lasting 6–30 seconds."  MDC Field Guide
"A little privacy please."  The male is considerably smaller than the female.
Toad eggs - REK
Mating begins with the long trills of the male's love song.  Breeding occurs in small ephemeral ponds or collections of water.  The photograph above was taken at a puddle left by a flood in 2011.  The female will lay 2,000 to 20,000 eggs in long double strands which develop into tadpoles over 2 months.  This is a risky business as the pond can go dry and eggs are high on the diet of many things living around the pond.

The tadpoles, like the adult, secrete a protective chemical from their skin called bufotoxin which can make predators sick.  It can be irritating to our mucous membranes and can make your dog sick but as Amphibiaweb.org mentions "toads have little defense against boys" who can be very destructive in breeding season.

Back to Bruno's find, the dwarf American toad, Anaxyrus americanus charlesmithi.  "It is smaller (only about 2 inches, snout to vent) and more reddish brown, with fewer, smaller, or no dark spots on the back; belly is cream colored with a few dark gray spots on the breast. " (MDC)  The parotoid gland is much less prominent as seen above.

The proper grip - note the red dots
When holding a toad or frog for photography, pinch a front and back leg on one side between your thumb and fore finger and they will stop kicking and hold still, but they still won't smile for the camera.  I taught Bruno this trick but he couldn't teach me how to pounce on them.

Extensive information on both species is at this Amphibiaweb.org site.

Saturday, September 9, 2017

Red-backed Black Widow

Gala sent me this picture of a black spider resembling a black widow but with red on its back.  She wisely didn't pick it up to see if there was an hour glass on its tummy.  We had written about black widows in several blogs and all the widows I have seen had pure black backs so I doubted this was a black widow.  It turns out I was wrong, not a surprise to my wife, Barb.

This is is a northern black widow, Latrodectus variolus, a different species from our southern variety, Latrodectus mactans. Here is what Bugguide says about it:
"For the northern black widow, the hourglass is distinct, but is broken(1) (whereas the southern black widow's hourglass is complete) and typically there is a row of red spots down the middle of the back and possibly some diagonal whitish bands on each side; the bands are typically observed on the younger, more juvenile widows."

Two days old
Sealed in a magnifier box - lots of tape!
A few years ago we blogged about how male black widows danced to avoid being eaten. This included the egg sacs that we raised in our house at the creek. I say "we" as Barb put up with it with a lesser degree of enthusiasm. Having raised them, I felt a degree of a paternal relationship and was conflicted about what to do with them. They handled part of the problem as their numbers declined daily due to cannibalism of their siblings. In nature, if all the spiderlings are the same size, cannibalism is less common.*

Eventually I was out voted in releasing them and they stayed sealed up for a year to ensure they were neutralized. I felt better knowing that a female will have 9 to 15 eggs sacs with 100-900 eggs apiece over her lifetime so she probably didn't miss these.

* How black widow mothers control their children’s cannibalism

Thursday, September 7, 2017

Horse Fly Larvae

Horse Fly Larva
We recently wrote about the horse fly, the big buzzing pesky devils whose females bite to obtain blood necessary to produce their eggs.  I just came across one of their kids deep in a gravel bar.


I was with Deb Finn and Nathan Dorff of MSU, exploring gravel bars along Bull Creek as research sites.  We hiked up Peckout Hollow, an ephemeral drainage that has been dry for weeks.  There we found an uprooted tree and a deep hole washed out by a previous flood.  In the bottom there was a small shallow water pool a foot in diameter.  Nathan began digging away the gravel and came up with this horse fly larva.

Black Horse Fly Larva - Tabanus atratus *
"The larvae are long and cylindrical with small heads and twelve body segments. They have rings of tubercles (warty outgrowths) known as pseudopods round the segments, and also bands of short setae (bristles). The posterior tip of each larva has a breathing siphon and a bulbous area known as Graber's organ." Wikipedia on Horse Fly

Horse fly larvae generally are found in freshwater streams and moist soil.  Finding this one far from the creek is a reminder that water continues to flow under apparently dry gravel bars.  They even found a small crawdad!  Nathan's interest is in studying the ecology of water under the gravel and the invertebrates living there.

My favorite way to see a horse fly.
The larvae of most horse fly species are predators, feeding on worms and insect larvae although some of the larger species will attack tadpoles, frogs and toads. Unlike a lot of fly larvae, mine seen in this video manages to get around quite well with its six stubby legs.  They can have toxic saliva that helps to subdue their prey.  Depending on the species they can go through 6 to 13 molts before forming the pupa.  There is one generation per year but some species will develop to adulthood over 2 years.**

Having recently been tormented by some of its kin, I felt no guilt in keeping this specimen to the end of its life.  It may mean one less bite on my next hike up the hollow.

I found it was still alive in the specimen container of water a month later as seen in this video.  I am now keeping it in water filled with ostracods to see if I can get it to pupate.*
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*  Note 11-8-2017:  Identified as Tabanus atratus by Dr. David Bowles who published a study on the species in 2008.
**Purdue University Entomology Extension