False Milkweed Bug

False Milkweed Bug
False Milkweed Bug

The False Milkweed Bug (Lygaeus turcicus) is a seed bug that, although quite similar in appearance to the Small Milkweed Bug (Lygaeus kalmii), is not strongly associated with milkweed.

False Milkweed Bug
False Milkweed Bug

As can be seen in the photograph above, the False Milkweed Bug is most often found feeding on yellow composites (Family Asteraceae).  These bugs were all photographed at Shaw Nature Reserve on what seems to be this insect species’ favorite food plant, the False Sunflower (Heliopsis helianthoides).

False Milkweed Bug
False Milkweed Bug

There are several members of the Lygaeidae family that are aposematically colored and found in North American prairies.  As mentioned, it seems that the False Milkweed Bug does not typically utilize milkweeds.  The Small Milkweed Bug feeds on milkweeds as well as other plant taxa.  The Large Milkweed Bug feeds exclusively on milkweed.  There is obviously a great case of Mullerian mimicry (distasteful organisms appearing similar to one another to benefit from a an easily identified color or body type) going on here, but it gets pretty complicated.

What has happened to the False Milkweed Bug?  Is this a case of a species that once fed primarily on milkweed and developed aposematic coloration but has since switched food preference?  Or, is this a case of a palatable species mimicking (Batesian mimicry this time) the aposematic coloration of a truly noxious species?  Thinking about this, it is easy to see the selective advantages that could result from either possibility.

First, a little background…
Some insects that feed on milkweed benefit by concentrating chemicals called cardiac glycosides that are toxic irritants to vertebrate predators.  Cardiac glycosides are an irritant to vertebrate herbivores (livestock) and vertebrates that feed on insects that feed on milkweed and store these compounds in their tissues.  However, they are not a significant problem for insects that feed on milkweeds – they simply pass through their guts (insects that store these specific toxins, for example the monarch, must have biochemical changes to avoid toxic effects).  The milkweed’s primary defense against the seed bugs and other herbivorous insects is the milky sap that gets forcefully pumped from any mechanical damage that is inflicted on the plant.  For this reason the milkweed is a pain for an insect to feed on.

For a seed bug, with its piercing-sucking mouth parts, feeding on the gummy sap of a milkweed is a significant hurdle.  Assuming the False Milkweed Bug once fed from milkweed primarily and gave it up would be a significant advantage.  Keeping the aposematic coloration, which would allow it to gain the benefit from its vile-tasting, similarly colored cousins, still feeding on milkweed, would be advantageous as well.  With my brief observations, the False Milkweed Bug still behaves conspicuously – feeding and doing everything else it does out in the open, suggesting that the aposematic coloration is still working in this mimic-model system, whatever the source history ultimately may be.

-OZB

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Short-eared Owls and a Christmas Moon

SEOW & Christmas Moon
SEOW & Christmas Moon

Wow.  I’ve been looking for an evening like this for a number of years.  I have heard and read that Short-eared Owls will often start their night early and often will often be up and active with several hours of day left.  I have seen them before at dusk, right before sunset, but last night at B.K. Leach C.A. we had several on the move with almost two hours of light left.  We were able to count a minimum of eight SEOW, but there may have been more.  Immediately before sunset I was able to observe somewhere between 25-30 Northern Harriers along with the owls.  It was quite a treat, listening to the Owl’s peculiar barks and screams as they were dog-fighting with the other owls and the Harriers who were looking for their spots to spend the night.

Short-eared Owl
Short-eared Owl

-OZB

Floating the Upper Current

Upper Current in Autumn
Upper Current in Autumn

I’m finally ready to share a few more images from a float down the upper third or so of the Current River that Steve and I had the great fortune to experience this past October.  We started at navigable mile 8.0 at Cedar Grove Access and pulled out three days later at mile 51, the confluence of the Current and that other, oh-so desirable, Ozark stream – the Jacks Fork.  If one floats slow and quiet, the opportunity to see wildlife is very high in this National Park (Ozark National Scenic Riverways N.P.).  I’v shared a couple of images of these guys previously.  I believe we found 8-9 Mink during the first day of this float.  It was enjoyable watching them busily hunt along the stream banks, mostly oblivious to our presence.  As usual, Steve did a great job in keeping us quiet and pointed in the optimal direction for capturing some images.

American Mink
American Mink

It was quite a challenge to keep up with these guys as they fished.  This one below had caught a nice-sized crayfish and barely slowed to stop and enjoy his snack.

Ozark Lobster!
Ozark Lobster!

Here is a photo of one investigating the water prior to dipping back in.

Testing the Water
Testing the Water

Not only does a float down the Current allow for great observations of wildlife, but many geological features are most easily seen by being on the river as well.  Cave Spring can now be accessed via a nice newer trail, but it is much nicer accessing it by boat.  The endpoint of a vast and interesting karst drainage system, Cave Spring rises from the back of a short cave.  At the rear of this cave one can guide a boat over the vertical conduit of the spring, which is ~155 feet deep!  What an eerie sensation it is to shine your light down and still see no more than a fraction of the length of the conduit shaft.  In the image below, I am on a dry exposed shelf adjacent to the spring’s outlet and Steve is guiding the canoe towards the river.

Cave Spring
Cave Spring

Pultite is a spring found on this upper stretch of the Current River that is surrounded on all sides except the river by private property.  This means that one must boat or wade/swim to visit it.  At only ~ 1/10 the output of Big Spring, Pultite is still quite a good-sized spring with and average daily output of ~ 25 million gallons.  The effluent channel on this one is quite attractive and I hope to visit more often.

Pultite Channel
Pultite Channel

If day one was for the Mink, day two was our River Otter day.  We had no Mink, but 5 or 6 of these large weasels were spotted.

North American River Otter
North American River Otter

Not to forget the birds!  These days, a trip to nearly any permanent Missouri water source will likely bring an encounter with a Bald Eagle.  Observing these guys in the Ozarks will never get old to me.

Bald Eagle
Bald Eagle

Another constant companion on these floats are the Fish Crows, here pictured finishing up a little Ozark lobster.

Fish Crow
Fish Crow

We were fortunate in having mostly clear and dry skies on this trip, which allowed us to throw our bags directly on whatever gravel bar that struck our fancy and sleep directly underneath the stars.  A morning fire was necessary – not only to burn the dew off of our sleeping bags, but of course, for the river-water French-press coffee.  Dark skies on these streams afford great opportunities for astrophotography.  My only wish for this trip is that I was a little more tolerant of the cold, tiredness and laziness that limited my patience for getting better nightscape images… 😉

Nightscape on the Upper Current
Nightscape on the Upper Current

I will be posting more images of this trip on my Flickr account in the near future.  Thanks for visiting and I hope to post again in the near future.

-OZB

 

Plant Parasites

Dodder on Rosinweed
Dodder on Rosinweed

Most of us are familiar with many of the parasites that infect animals, since we, as animals, are susceptible to many.  Tonight I am sharing a few easily spotted and recognizable forms of parasitism in the plant kingdom.  The photograph above was taken, as were all in this post, at Shaw Nature Reserve and shows a relentless parasite that can infect a number of prairie plant species.  Dodder (Cuscuta sp.) is an obligate parasite, meaning it must find a specific living host plant to infect in order to survive and reproduce.  One can see by the orange coloration, this plant does not contain chlorophyll and must pull the necessary nutrients from its host plant.

Silphium Gall Wasp
Silphium Wasp Gall

The next parasite is of a form that I am just beginning to study and am finding quite interesting.  Plant galls are simply growths of plant tissue, formed not by the host plant, but by other organisms.  The variety of gall former as well as gall formation is astounding, to put it mildly.  Insects are the primary organisms that cause gall formations, but other arthropods, fungi, bacteria and viruses form galls as well.  Researchers are just beginning to learn the basics behind how these parasites cause the formation of such specific, and often beautiful galls.

The particular gall that is found on this poor Rosinweed plant pictured above is caused by a Silphium Gall Wasp (Antistrophus sp.).  One of the gloriously interesting facts about galls, much like other forms of parasitism, is the specificity most commonly found between host and gall former.  Most often a gall former can infect only one species of plant, or sometimes a group of closely related plant taxa.  Such is the evolutionary arms race between host and its necessarily specific parasite.  In the case of so many prairie host and gall former relationships, the outcome is sad for both.  The near elimination of this habitat has caused dramatic reductions in the variety and abundance of prairie plant species, and accordingly, has had similar effects on the insects that form galls on these plants.

Silphium Gall Wasp
Silphium Gall Wasp

Having observed these galls for so many years, I decided to cut one open to see the developments within.  A single gall can host many developing was larvae.  In this small section I was able to count no fewer than five wasp galleries, each harboring a developing wasp.  The two examples of parasites presented above are just a small example of the number of parasitic species that the Silphium support.  A number of other insects/arthropods use Silphium for food and shelter.  Birds love the seed and use the plants’ long strong stems for perches.  In many ways the Silphium are keystone species and can be considered as important to the prairies as trees are to the forests.

Grape Phylloxera
Grape Phylloxera

Grape Phylloxera is caused by an aphid-like insect and is a parasite to native grapes.  In the mid-1800s this species was accidentally released in Europe and nearly destroyed the French wine industry.  The life cycle of this insect and its relationship to its host is mind-boggling.  As many as 18 different life stages have been identified – from sexual to asexual, winged, foliage feeding to root feeding.  This complexity, as with so many other multi-stage, specific host-parasite relationships creates major problems in man’s attempt at developing commercial controls.  To date, this parasite cannot be controlled with any pesticide solution; the only remedy is still resistant stock that nature has developed in this host-parasite arms race.

-OZB

Strawberry Bush

Strawberry Bush
Strawberry Bush

The Strawberry Bush is a rather new one for me.  Steve and I found these plants, with freshly opened fruit capsules along the St. Francis River within Millstream Gardens CA this autumn.  Rare due to loss of preferred habitat, this plant prefers moist, sandy soils along stream banks.  Along with the St. Francois Mountain region, this plant also grows in extreme south-eastern Missouri.