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

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

Macro Monday – Grey Treefrog

Grey Treefrog
Grey Treefrog

While hunting for interesting arthropods to shoot this summer at the wetlands of SNR, I cam across a large number of younger Grey Treefrogs.

Grey Treefrog
Grey Treefrog

Some folks might get confused by the green coloration of the young Grey Treefrog, however this is likely due to the younger frogs being fond of denser vegetation.

Grey Treefrog
Grey Treefrog

-OZB

A Few Flighty Flies

Robber Fly
Robber Fly

I find the flies to be one of the more interesting groups of insects and I was constantly on the lookout for new species to photograph this summer.  There is such diversity in the flies, from size to form and function.  There is still so much to learn about some flies, including some rather common species that researchers have still not described where or on what the larval forms live.  To start, here is a closeup of a true giant of the flies, a Robber Fly (Family Asilidae).  The Robberflies are true predators, with an intimidating beak that they use to inject neurotoxic and protein-dissolving cocktails.

Trichopoda pennipes
Trichopoda pennipes

The photograph above showcases a fly that should be a favorite of gardeners and farmers.  Flies in this family (Tachinidae) parasitize a number of different insects and this species specializes in many of the plant-feeding true bugs like Stink Bugs and Leaf-footed Bugs.  The generic name can be translated from Greek to mean “hairy foot” and the specific name “pennipes” means feather.  This namesake feature can be seen on the rear legs of this fly in the photograph above.

Thick-headed Fly
Thick-headed Fly

The Thick-headed Flies are extremely interesting and a joy to watch.  These guys not only mimic bees and wasps, but they also parasitize the hymenoptera by depositing their eggs on the stinging insect, sometimes attacking the host to place their egg.  The eggs hatch and the larvae become internal parasites of their host.

Geron Bee Fly
Geron Bee Fly

The minuscule Bee Flies in the genus Geron parasitize moth caterpillars.  The adults of these flies feed almost exclusively on yellow-flowered Asteraceae.

Scorpion Fly
Scorpion Fly

Don’t be threatened by the sting-like structure that this Scorpionfly (Family Panorpidae) has arched over its back.  This is simply the male genitalia and is quite harmless.  Scorpionflies primarily make a living by scavenging on dead insects, and like many flies, exhibit elaborate behaviors to attract mates.  These flies will perform various dances in front of females and will often provide a ripe insect carcass as a prenuptial gift.

So Long!
So Long!

Finally, here is a rather different view of a Greenbottle Fly.  I hope this helps to describe some of the fascinating diversity in form, function and behavior that can be found within the Diptera.  These are but just a few of the easier to find and photograph!  I hope to continue my exploration of these fascinating insects next year.

-OZB

Eastern Gamma Grass

Eastern Gamma Grass
Eastern Gama Grass

Today I am sharing a few photos of Eastern Gama Grass (Tripsacum dactyloides), an interesting plant that grows in abundance at Shaw Nature Reserve.  This warm-season grass has a C4 metabolism and can grow in a wide variety of habitats.  Due to its use as a forage crop, man has introduced this perennial plant across the Americas.  Gama Grass is a distant relative of maize, separating approximately 60,000 years ago.  The inflorescence of the plant can be seen above.  Whereas maize has its male and female flowers borne on separate spikes, Gama Grass carries its flowers on separate sections of the same terminal spikes.  You can see the exposed anthers towards the upper 75% of the spike, while the developing seed are located in the lighter green sections nearest the stem.  The photograph below shows a closeup of the exposed stigmas, waiting for the wind-borne pollen.

Gama Grass Stigma
Gama Grass Stigma

In the final image, you can see a grape vine using a Gama Grass spike for its support.

Architects
Architects

-OZB

A Few Skimmers

Blue Dasher Male
Blue Dasher Male

The skimmers (Family Libellulidae) are the largest family of the Odonata and contain some of the most widely known and conspicuous dragonflies.

Slaty Skimmer Male
Slaty Skimmer Male

Much like a flycatcher within the world of birds, the skimmers typically sit and wait on a perch and fly to catch an insect.

Widow Skimmer Female
Widow Skimmer Female

These photographs were taken at a small pond at Shaw Nature Reserve this summer.

Widow Skimmer Male
Widow Skimmer Male

-OZB

Garden Fleahopper

Garden Fleahopper
Garden Fleahopper

These tiny ones are ubiquitous in a number of habitats and host plants, reach 1-2 mm in length as adults and are pests to a number of agricultural crops.  This brachypterous (short-winged) female was photographed on a Maypop vine (Passiflora incarnata) at Shaw Nature Reserve in the northern Ozarks of Missouri.

Garden Fleahopper
Garden Fleahopper