Dung Beetle

I was preparing to dip some water from one of my rain barrels when I found this beetle floating inside.  It appeared dead, but its legs moved when I plucked it from the water and it became more animated as it dried.  This beautiful beetle, Dichotomius carolinus, largest of the local Dung Beetles, was cause enough to take a break from my work to examine this magnificent specimen.

The beetle at first appeared to be adorned with pale stripes.  Closer examination revealed the stripes to actually be soil caked into grooves on the wing covers.  Dung Beetle larvae develop in the ground at the bottom of a deep burrow where they feed on a supply of dung placed there by the adult beetle.  The beetles can accumulate soil on their bodies when digging nest burrows or when burrowing out of the soil after pupation.

This is one tough beetle.  It measures just an inch or a little better, but feels like a stone resting in the palm of your hand.  If you try to hold it in a closed fist, it will use its strong front legs to force your fingers apart.  The photo shows the pose the beetle adopts when it begins digging.  Front legs try to force the soil sideways while the scoop shaped head forces lose material up and away.

All six legs are designed for digging and scooping.  Dung beetles feed on manure produced by large mammals, primarily domestic cattle and horses.  Their actions in a pasture situation are considered beneficial to the plants and soil because of the burrows and incorporation of manure into the soil profile.  Livestock also benefit by the rapid reduction of concentrated manure which results in fewer pests and parasites surviving within the manure piles.  Several exotic species of Dung Beetles have been intentionally introduced into the United States in an attempt to maximize the benefits of this group of insects.

Dichotomius carolinus is a native species and is typically not the most abundant Dung Beetle species in an area.  Most dung beetle research concentrates on grassland areas dominated by domesticated livestock, so the beetles are interacting with non-native species.  I wonder if this Dung Beetle species utilizes manure from the Whitetail Deer?  I’m sure they would have used manure from Bison, but Bison were extirpated from Ohio over 200 years ago.  The deer is the largest free ranging native ruminant in this area and hopefully produces a large enough concentration of manure to satisfy this particular Dung Beetle.  I may have to set up a couple of deer manure traps and see what shows up.

I found this neat mite living on the beetle’s body.  I’m not sure if it is actually a parasite or if it is just hitching a ride.  Each individual manure drop supports its own special ecosystem in which myriad species feed upon the manure and each other.  Some species are able to move from one manure source to another on their own power.  Species with limited mobility often use the more mobile species as transportation to fresh manure.

The mites preferred lodging was beneath the head near the attachment of the front legs.  That’s where it was when I set the beetle free.  Hopefully, both beetle and passenger found their way to fresh manure.

Living Raft

I found this raft of living arthropods floating in the overflow pool of the water garden.  Riding the surface tension of the water, they have been drawn together into a colorful wriggling mass.

At first glance, the living raft appeared to be just another collection of debris floating across the water.  There’s always something floating in the water.  Usually it’s just dust or accumulated pollen or debris from the dwarf pine that hangs over one edge of the pool.  On rare occasions there will be something strange trapped by the water, so I stop and take a look every time I go past.

The sun reflecting from the little bodies caused the whole cluster to sparkle.  Besides those creatures already forming large aggregations, there were many floating as pairs or single individuals.  As the wind moved the large group around the pool, it collected the single drifters into its congregation.

It was hard to get a good look at the raft with the wind blowing it constantly around the pool, so I scooped it up in a shallow bowl and took it to a sheltered place for observation.  The raft seemed primarily composed of various species of Springtails and Mites.  These are common creatures of the soil ecosystem that live near the surface of the soil or in decomposing plant material covering the soil.  Besides being active creatures, they can exist by the thousands in a square foot of soil surface area.  It’s no wonder that a few of them would fall into a pool of water set flush in the ground.

The various species of Springtails and Mites definitely dominated the mix, but there were other soil arthropods present.  This small spider stood free of the water and ran unencumbered over the bodies of its companions.

A few of these denizens of the soil look quite large compared to the others, but the largest was just at the one millimeter mark.  This is what’s underfoot when you walk through the fields.  They play a vital role in the decomposition of organic materials, release of plant nutrients and control of soil born diseases.  It’s not often that they come out to display themselves in such an easy to view array.  After the photo shoot, I released all back onto dry land.  I also quickly washed the cereal bowl and put it back in the cupboard, before my wife saw what I was doing.