Grasshopper and Spines

A grasshopper perches on a spiny plant.

Spotted this guy striking an artistic pose on a spiny plant at an Argentinian field site and had to snap a photo.

A male lubber grasshopper (family Romaleidae) of genus Staleochlora. More on these guys next week!

Your insect vocab of the day is ‘arolium.’  This is the pad visible between the two claws at the end of the front leg.  This structure acts as a suction pad, producing a sticky secretion that enables the insect to climb smooth surfaces.  Not all insects (or even all grasshoppers) have this structure.

Sweep Netting

Sweep netting in a field of flowers (Welder Wildlife Refuge).

New page up in the techniques section.  Please check out my discussion of sweep-netting as an insect collection technique.

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For more techniques for insect collecting and rearing, see the techniques section.

Roach Revisited

A field roach in Argentina

A pretty little Argentinian field roach in the family Blattellidae.  We have these guys in the US, too, but you won’t find them infesting your kitchen.  These guys stay outside and feed mostly on flowers.  Unlike many roaches, they are diurnal (active during the day), and frequent flowered fields and clearings.  Roaches have always been the bug that freaks me the heck out, but apparently I’m fine with them so long as they stay out doors.  Although there are over 4000 known species of roaches only 7 of them are considered severe pests.  Most ‘wild’ roaches inhabit environments away from interactions with humans.

An easy way to distinguish roaches (order Blattodea) from other insects is the large, shield-like pronotum, which is often expanded to cover most of the head.  The pronotum is the upper surface of the insect’s prothorax: in this case the large, yellow-bordered ‘plate’ just behind the head.  This character is distinct even on wingless roaches, such as juveniles or the Madagascar hissing cockroach.

Science part’s done now.  The roach-squeamish may be excused as I head into anecdote time.

Entomology is fun.  As I experienced in Argentina, the reaction of a group of entomologists, on seeing cockroaches on the walls outside a restaurant, is to pause and discuss the species of the roach before heading on in to dinner.  Most normal human beings consider this atypical behavior.  Of course, there are levels of eccentricty, even within the field.  For example, my labmate Paul and I took a break between courses to head back out and take photos.   (These may show up here later.  Are you excited?)

And then Paul (an avid collector) surpassed us all by sticking a few in a ziplock bag where they remained in his pocket during dinner.  Appetizing!

Doggy bag of roaches!

Spreading Insect Wings

A spread luna moth, with spreading board in the background.

New page up in the techniques section.  Please check out my step by step photo guide to spreading insect wings.

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For more techniques for insect collection and rearing, visit the techniques section.

Ant Picnic – Acrobat Ants

Acrobat ants (Crematogaster) feast on a katydid.

I discovered this grisly scene by following a trail of acrobat ants across the red brick courtyard of our Argentinean hotel.  Hundreds of worker ants trekked nearly 20 meters from their nest to the scene of the massacre where they joined their sisters in chewing through the katydid’s tough exoskeleton to burrow their way into the soft tissue beneath, carving up their kill to bring food back to the nest.

Acrobat ants (genus Crematogaster), are typically arboreal, or tree-nesting, ants.  Their petiole, or waist, connects to the top of their heart-shaped gaster (the third body region of ants).  This allows them to flip the gaster up over their backs, both for balance while navigating their tree habitat, and defensively like the stinger of a scorpion.  Acrobat ants wield their venom in a defensive spray rather than a stinging injection.  This is an effective weapon of chemical warfare against other arthropods and small organisms, but generally passes unnoticed by humans.  Their mandibles can still deliver a pinch, however, and they will attempt to follow a bite with a spray of formic acid into the wound.  Although I took this picture in Argentina, acrobat ants are relatively common across the United States.

In the Mound – Termites

Termite workers carry brood to safety in an opened mound.

Opened up this mound of termites in a cow pasture in Argentina.  The landowner there was extremely nice and showed us all around his property in our quest for fire ants.  In Argentina, where fire ants are so much less prevalent (albeit native), they hardly even know what you’re talking about.  The big pest species are the carpenter ants that make huge rock hard mounds everywhere that wreck the plows and cause holes that break the cows’ ankles.

Like ants, termites (order Isoptera) are social insects with a caste system in which individuals with different tasks express different body forms.  Termites have both a queen and a king, who may live as long as 20 years, an virtual infinity compared to the short-lived male and female workers and soldiers.  Workers forage or care for the eggs and larvae (the small white termites in the picture).  Soldiers have large jaws and extra thick ‘skulls’ to reinforce the head capsule against the power of the enlarged jaw muscles.  In the picture this is visible as darker heads from the reinforced exoskeleton.

Close up of termite workers.

Mantis Meal

A mantis munches on a struggling skipper.

The frantic fluttering of this skipper caught my eye at one of the Argentinian field sites.  The mantis that had snatched the little butterfly had only got hold of one wing, and couldn’t quite seem to manage to get her lunch under control.  After a valiant struggle, and some munching on the wing, she eventually lost her hold, leaving the mantis hungry, and the skipper crippled on the ground below.  Being a bug is not much fun.

Quite a number of insects have independently evolved raptorial forelegs for capturing their prey, but mantids (order Mantodea) are by far the most well known for this feature.  Raptorial means ‘grasping’ or ‘adapted for seizing prey’ — think of the talons of birds of prey (raptors) or those of the cunning velociraptors from Jurassic Park.  The opposable spines on the mantid’s front tibia and femur fulfill a similar purpose, and their long reach and speed make them dangerous predators in the insect world.  Mantises have even been known to lurk on hummingbird feeders and pick off the unwary bird.