Ants and Dragonflies

 

The year is full of seasonal events.  Some I like and some I don’t.  As I was heading home yesterday evening, the road through our nearest town was closed in preparation for the annual fall street fair.  That’s one of those events I don’t like.  When I finally pulled into my driveway, I saw a large dragonfly swarm circling the Prairie Garden.  I always enjoy the fall swarms of dragonflies and this one was partly created by another of my favorite events.  Ants were swarming.

Ants taking off on their mating flight remind me of chumming the water for sharks.  Dragonflies come from all directions to feed on the ants.  This is usually an evening event and the lowering sun lights up both ants and dragonflies.  Unfortunately, it’s almost impossible for me to capture a photo that comes close to illustrating the beauty of the interaction between these two insects.  Nobody would guess that this photo contained a couple dozen flying ants and four dragonflies.

Occasionally I’ll capture an image that is recognizable as a dragonfly.  They all appeared to be Common Green Darners.

Other photos seem more suited to proving the existence of pixies or tiny x-winged fighters cruising above the fields of Blue Jay Barrens.

The dragonflies seemed to be targeting the large queen ants.  The queen’s flight was rather slow and there was a good bet that a dragonfly would nab her before she topped an altitude of 12 feet.  I think I just caught the tail end of the swarming event.  I probably would have been home in time to see the entire swarm if I hadn't had to detour around town.  During the peek of the swarm there would have been far too many ants in the air for the dragonflies to have caused much damage.  Those last few ants would have been trying to survive a sky full of predators.

The ants attempt to reach a high point, such as the tip of a blade of grass, before launching into the air.  This queen kept running up the grass blade and plummeting from the tip back down to the ground.  That’s probably why she’s one of the last to take to the air.  Maybe it’s best for her to be eaten, so she doesn’t pass on those bad swarming traits.

The workers and winged males were very small.  I had to crawl with my face almost to the ground in order to find them.  During the search, the neighbors drove past the house.  They just waved.  I guess my behavior no longer strikes them as being odd.

Amidst all of the workers was one that carried an ant cocoon in its jaws.  I guess being late hatching doesn’t excuse you from swarming.

A Few Dragonflies

The drought has desiccated the Blue Jay Barrens landscape, so it’s fortunate for me that you don’t need open water in order to attract dragonflies.  Many travel far from water in their pursuit of prey and can be found in just about any open field.  Unlike many other animals, dragonflies are arriving on schedule and in normal numbers.  This is a male Eastern Pondhawk, a species that normally sits on the ground or in low vegetation and attacks upward at passing insects.  My first glimpse of this species is usually when I scare it from its perch.  They normally don’t fly far and are easy to track to their new landing site.

In many species of dragonflies, males and females have distinctly different coloration and patterns.  The female Eastern Pondhawk is predominantly green with a black pattern on the abdomen.  That should make it easy to both identify and sex this species, but the males begin their adult lives looking just like the females.  A view from the side would show the female’s ovipositor, but I managed to miss that view.

The male Common Whitetail looks to have its abdomen covered in powdered sugar.  As a child, this was one of my favorite species.  The white coloration is quite brilliant and makes this an easy species to spot.

Males of other species also have the powdered abdomen, but none is quite as bright as the Whitetail.  The abdomen of this Widow Skimmer looks to have more of a blush of white.  Fortunately, wing patterns quickly distinguish the different species.

The female Widow Skimmer is another of those species that differs greatly from the male.  Immature males share the female’s appearance, but the females have darkened wing tips.  Personally, I don’t get too excited about distinguishing the immature males from females.  From a management standpoint, being able to identify the species is all that’s really necessary.

Looking superficially like the female Widow Skimmer is the female Spangled Skimmer.  The eye is first drawn to the abdomen with its central brown stripe flanked by bright yellow.  The thing that automatically sets it apart is the presence of white or yellow spots on the leading edge of the wing near the tip.  These patches of color are contained within a feature of the wing known as the stigma.  In most species, the stigma is solidly colored and appears as a dark rectangle.  In the Spangled Skimmer, the stigma is part light colored and part dark and is impossible to miss.  These are all common species that I see every year, but I always enjoy their presence.

Return of the Pond

We accumulated three inches of rain last week. That was enough to raise the well level by three feet and produce a small pool in the pond. Birds have swarmed in to use this water source for drinking and bathing.

The water is only a few inches deep, but that’s enough to transform the area from a terrestrial to an aquatic habitat. According to the long range weather forecast, we’re in for a few months of wet weather. If that occurs, developing aquatic life should enjoy another seven or eight months of open water.

It takes a while for the pond bottom to regain the appearance of a true submerged environment. Cracks that developed with the final disappearance of water a few months ago are still visible. Aquatic life will soon abound and the multitude of bottom dwelling organisms will sift through the mud until it once again becomes smooth.

Ruby Meadowhawks are the first to take advantage of the newly restored pool

Reproduction is their principle reason for coming to the shallow water. Several pairs cruised the water’s edge in search of suitable places to deposit eggs.

This species often flies in tandem while laying eggs. The male uses a special feature near the end of his abdomen to grasp the female just behind the head. He then leads the female to selected egg laying sites and directs her egg laying activities. This process also helps to protect his mate from potential rival males.

The pair will hover above the water and make occasional dips downward in order to release eggs. The eggs may be released directly over the water or they may be dropped in low lying areas that have the potential of being inundated in the future. When the population of little aquatic animals begins to blossom, the dragonfly larvae will be there to eat their fair share.

Almost UFO's

I call these almost UFO’s because I know what they are and some people could probably figure it out from the photo. The yard was aswarm with dragonflies grabbing ascending winged ants rising from the lawn and I was futilely trying to capture the event. Even if I did get a clear image, it’s impossible to capture the beauty of a dragonfly swarm glittering in the setting sun.

The dragonflies were quick to take advantage of the ant exodus. The departure of reproductive individuals from an ant colony is a short duration event. More ants in the air means fewer total victims of predation. The timing also makes it less likely that predators will be able to accumulate in large numbers quickly enough to be a major threat to the ants. I observed both queen ants and the smaller males heading into the air. From what I could see, the dragonflies targeted the queens. Queen ants must be packed with nutrients because I’ve never seen a predator pass up a queen.

The dragonflies all appeared to be Common Green Darners. As the days shorten, dragonfly swarms will become increasingly common. This was a small swarm of around a dozen individuals. I’ve seen September swarms that contained hundreds of dragonflies.

By the time I turned my attention to the ants, the queens had all departed. The males were still launching at a fairly steady rate.

The males will catch up to the females and mate in the air. Other colonies of the same species are probably launching at the same time. As I watched, the workers and remaining males suddenly headed down the grass stalks and returned underground. There’s a good chance that they’ll be back at it tomorrow evening.

More Dragonflies

Dragonflies have been swarming around the pond in tremendous numbers, but I actually encounter more different species out in the fields where they spend their time hunting. This is a female Eastern Pondhawk, an aggressive species that perches on the ground and zooms up to grab insects flying over.

I always try to take pictures of dragonflies from two different angles. Having a side view and a top view usually shows me the details necessary to make a proper identification.

Of course, I always have a few shots from odd angles. I saw this dragonfly shoot into the grass and made a quick shot just in case it got scared away before I could get a better angle. I needn’t have worried. As I moved around, I scared up a few insects that the dragonfly flew up and grabbed. At one point it actually circled my feet watching for more insects to come out of the grass. According to the text, this is a common behavior for this species.

I was really excited to get a shot of this Arrowhead Spiketail. This is a species that lays its eggs in tiny streams or springs. I’ve watched them cruise up and down the creek, but never got a photo opportunity or a good enough view for an ID. The Arrowhead in the name refers to the arrowhead shaped markings on the upper side of the abdomen.

I was crouched down beside the creek, just dabbling in the water, when the Arrowhead Spiketail came up and perched a few feet in front of me. This is the northern form of the species, recognized by the green eyes and the bright yellow markings.

There are many good dragonfly identification books available that cover all the species you are likely to encounter in a particular area. This makes it possible to identify most species you see. The problem is that many species have distinct male, female and juvenile forms, so for each species you may have to remember two or three different images. This is the female form of the Common Whitetail I showed a couple of days ago. Quite a different animal than the male.