Archive | June, 2011

Nuptial Flight – The Sad Plight of Male Ants

24 Jun
Winged sexual male and female sugar ants prepare for their nuptial flight under the guard of the small black worker ants.

Male and female alates prepare for a mating flight while worker ants stand guard (Brachymyrmex).

Earlier this week I was treated to my mailbox colony of Brachymyrmex (no official common name, but around here we call them sugar ants*) throwing a mating flight party.  They live in the bricks of the mailbox, so the whole exterior was aswarm with the winged male and female sexuals (alates)  as well as an abundance of defensive workers, guarding the reproductives as they prepared for their flight.  I was particularly taken with the tiny frenetic males, who were adorable in their yellow-orange splendor and half-pint size.

Winged male sugar ants (Brachymyrmex) swarm in preparation for a mating flight, under the guard of workers.

Winged male sugar ants (Brachymyrmex) swarm in preparation for a mating flight, under the guard of workers.

In most species, male and female sexual ants are fairly easy to distinguish.  While both genders have enlarged thoraxes to host their wing muscles, the females, who will go on to be queens, tend to be larger, with swollen abdomens the better for mass-producing eggs.  The males, on the other hand, are essentially one-time sperm-transfer units.  They will mate (if lucky), and then die.  In this simple role, they don’t need all the complicated mental circuitry of the future queens, so they also tend to have smaller heads.  As the joke goes: Big shoulders, tiny brains:  that’s how you know they’re males.

Sexual male and female sugar ants (Brachymyrmex) with sterile worker ant.

Sexual male and female sugar ants (Brachymyrmex) with sterile worker.

*edit:*  Thanks to Danny McDonald for pointing out the the common name ‘rover ant.’  The Brachymyrmex species B. patagonicus is invasive in the United States and becoming an increasingly common nuisance pest in households.

Also check out Alex Wild’s excellent pictures on Myrmecos, including a mating pair.

Ant Farms: How to build your own formicarium

17 Jun

New page in the techniques section.  Please check out “How to build your own formicarium (cheap!)

I love keeping ants. They’re low maintenance, fun to watch, and a fantastic teaching and outreach tool. Kids and adults alike get excited to see the inner workings of a functioning ant colony, complete with queens, workers and brood. And fortunately, there are more and more resources available to the amateur ant-keeper. Unfortunately, some of these resources can cost you a bundle. I have embarked on a quest to make my own custom formicarium as cheaply as possible.

Find more help pages in the techniques section.

Little Green Men: Tree Crickets

10 Jun
A green, long-legged female tree cricket cleans her antennae (College Station, Texas).

A female tree cricket (Gryllidae:Oecanthinae) grooms her antennae.

Tree crickets are a fun, bizarre looking species of cricket in the subfamily Oecanthinae.  With their green color, delicate bodies, and strange flat wings on the males they don’t easily fall into the average person’s image of a cricket.  As their name suggests, these crickets live in trees and shrubs, where they take in an ominivorous diet of plant matter and small insects.  Because of this somewhat cryptic life history they are seen less commonly than they occur.  The best way to find tree crickets is beating trees and shrubs especially at night.  They may also be tracked by their calls, or come to lights.  The male and female pictured here turned up while sweeping brush at the Texas AgriLife field station.

A male tree cricket with wings specialized for courtship song.

Male tree crickets (Gryllidae: Oecanthinae) lack ovipositors and have flatter, broader wings specialized for courtship song.

The most interesting fact I learned about tree crickets:  When the male sings, his wing rise up, exposing a special dorsal gland that secrete a tasty snack for the female.  While she’s on top chowing down on this nuptial gift, the male takes the opportunity to mate, singing all the while.  The spermatophore that is passed from male to female remains partially extruded, so the snacking and singing serves an additional purpose.  The male must keep the female distracted so that she does not consume the spermatophore before the sperm has been transferred.

Bleeding Blister Beetles

3 Jun
A disturbed blister beetle secretes cantharidin (Elephant Mountain Wildlife Reserve).

A disturbed blister beetle (Meloidae) bleeds a defensive skin irritant and toxin from its leg joints. (Photo by Paul Lenhart)

Here’s a fantastic shot of  a blister beetle showing off its name sake (Thanks to Paul for the picture!).  When handled or otherwise disturbed (such as by a hungry predator) beetles in the family Meloidae secrete hemolymph, the insect equivalent to blood, from their joints.  In the above picture you can see the drops of yellow fluid at the beetle’s “knees.”  The hemolymph contains a toxin called cantharidin, which can cause skin irritation and blistering in humans and can be fatal to ingest.  Basically, they bleed poison.

The fellow above is male, as recognizable by the antennal kinks.  These kinks are used by males during courtship to entwine with the female’s antennae (someone blogged about this recently with excellent pictures, but I can seem to find the post*).  Only the male beetles produce cantharidin, but they pass it along to females as an extra benefit to mating.  Among blister beetles cantharidin actually functions as a female attractant.  Cantharidin extracts from blister beetles are used medically to remove warts and even tattoos.  Horses are particularly sensitive to cantharidin, and cantharidin toxicosis, caused by ingestion of alfalfa or hay products contaminated with blister beetles, can cause symptoms varying from “depression to severe shock to death.”

*Edit:  Found it!  TGIQ wins about a million points for the phrase ‘antennal foreplay.’