Archive | March, 2013

The Sad Plight of Male Ants (revisited)

29 Mar
Dead male winged ants in pile outside ant nest after mating flight.

Drifts of dead male alates.

Last fall I came upon this veritable drift of dead male fire ants, piled up along the sidewalk outside a large ant nest.  The worker ants there didn’t seem to know what to do with this sudden overabundance of dead bodies and were piling them up in heaps at the sidewalk edge and stuffing them into sidewalk cracks.

Dead male sexual fire ants on ground after nuptial flight.

Fire ants, like many social insects, mate in nuptial flights, swarms wherein thousands of winged sexual ants (alates) mate on the wing.  Afterwards, the females drop to the ground and shed their wings and become foundress queens, seeking out a place to rear their first brood.  The males drop to the ground and die.

Male alates drop to the ground and die after mating flight.

A male ant is pretty much a very streamlined sperm delivery device.  They hatch from unfertilized (haploid) eggs, they have big muscular backs for wing muscles, and tiny heads because they don’t need much in the way of brains.  Prior to their one and only flight they also void their gut contents and fill their abdomen with air to make themselves more aerodynamic (Wilson, “Insect Societies”).  After their mating flight the males may wander briefly on the ground for a period before their body inevitably shuts down and they die.

Male alates dead at the sidewalk edge.

The female alates, however, can go on to live more than twenty years.  Deborah Gordon has data on some of her long term study colonies of harvester ants going back to 1985.  Those colonies are as old as me!

Female alate fire ant explores nest hole.

Meanwhile a foundress queen sheds her wings and seeks a nesting site.

See also:

Black on Black

8 Mar
Face view of camouflaged daddy-longlegs spider.

A cryptic black harvestman blending in to the scorched bark of a tree in a post-wildfire zone in the Chiricahua Mountains in Arizona.

One interesting ecological factor to explore in the Chiricahua Mountains in Arizona is the vast areas that have been swept by wildfires in the past few years.  For example, the Horseshoe 2 wildfire in 2011 was the fifth largest wildfire in Arizona history, affecting more than 220,000 acres.  When I visited the mountains, acres of still-scorched trees surrounded by wildflowers and new growth sat side by side with untouched forest and thick underbrush making for an interesting environmental mosaic.  In some of the burned habitat I spotted the above harvestman blending in perfectly with the scorched bark–perhaps a something of a lucky break for this species?

Black daddy-longlegs spider on burned tree.

Camouflaged black harvestemen on burned tree.

Havestmen, more commonly called daddy longlegs, are a type of arachnid in the order Opiliones.  Although they are often mistaken for spiders harvestmen have very different biology and morphology, with a single pair of eyes, a wide connection between head and body, and no venom glands!  In addition, many opilionids are omnivores and scavengers, eating all manner of small insects, fungi, plant material, dead things, and even feces.  One other cool fact– paternal care has evolved in 5 independent lineages of Opiliones (Machado 2007).