Archive | March, 2010

Ants and Scales

26 Mar
Carpenter ants tend scales on a shrub

Carpenter ant workers (genus Camponotus) tend scales on a shrub in Argentina.

Scales (superfamily Coccoidea) are members of the same suborder of hemipterans as aphids, mealybugs, and whiteflies (Sternorrhyncha) but are just a little more bizarre.  They are the barnacles of the insect world.  These strange little insects have adapted to a point where they no longer need to move to gather food.  Their tube-like beaks are plugged into the plant equivalent of blood vessels, which carry nutrients to them.  Adult female scales thus no longer need trouble themselves with developing such trivial things as legs, antennae, eyes and wings, and are almost unrecognizable as insects.  The males, on the other hand, resemble small flies, and flit among plants in search of buxom, blob-like females to mate with.

While feeding on the phloem (or sap) of plants, scales take in an excess of sugar compared to other important nutrients such as protein.  To counter this, scales (and many other hemipterans) excrete a sugar rich liquid called ‘honeydew.’  Honeydew often attracts other insects such as ants, who drink the honeydew and sometimes tend the scales like milk cows, protecting them from predators.

A carpenter ant (Camponotus) tends scales on a grass blade.

A carpenter ant (Camponotus) tends scales on a grass blade.

Cryptic Cicada

19 Mar
A cicada camouflaged against the bark.

A cicada camouflaged against the bark.

We found cicadas like this one on trees all through our Argentina field sites.  They sing noisily, but are tremendously cryptic against the bark.  I practiced my auditory hunting skills, tipping my head every which way to locate the direction of the sound.  Occasionally I could triangulate the position of my noisy neighbor.  Trying to spot them was sort of like looking at a magic eye puzzle.  Stare long enough and sometimes you’d realize one was two inches in front of your nose.

Cicadas (family Cicadidae) are members of the hemipteran family Auchenorrhyncha.  This little fellow was a fairly small species of cicada, maybe 2-3 cm long.  Most people are familiar with cicadas for their loud courtship calls and the shed skins they leave stuck to the trees they feed on.  Cicadas spend most of their life cycle as larvae under the ground.  The most famous cicadas spend 17 years underground, emerging as adults in vast swarms before dying in 4-6 weeks.

Ambushed Wasp – The Ambush Bug

13 Mar

Wasp and ambush bug on flower.

An ambush bug preys on an unwary wasp.

Exploring an Argentinean roadside I spotted what I thought was a dead wasp on a flower.   Wondering how this wasp had come to perish so abruptly in her nectar gathering work, I looked closer.  I actually poked at her several times before I noticed the second occupant of the flower—an ambush bug enjoying a tasty wasp meal!

Ambush bugs are a subfamily of Assassin bugs, family Reduviidae.  Ambush bugs are “sit-and-wait” predators.  These highly cryptic (camouflaged) insects frequently lurk around flowers, where they pick off unwary visitors.  They have mantis-like raptorial forelegs to snatch their prey from a safe distance.   Like other true bugs (order Hemiptera, suborder Heteroptera) ambush bugs have a segmented tube-like ‘beak’ for feeding.  Ambush bugs insert this beak into a weak spot in their prey’s hard exoskeleton and suck out the fluids.