Orange Hoppers

Immature planthoppers hanging out in a fungal growth under a log.

I found these brightly colored insects tucked under a log in Arizona, where they appeared to be feeding on a growth of fluffy white material–perhaps fungi or mold.  These are immature planthoppers, members of the same group of tiny hopping green specks you sometimes run into in lawns or trees.  This was, for me, a pretty surprising place to encounter a hopper, so I looked around to see what else I could find out about these little fellows.

The lovely community over at BugGuide has tentatively identified these as members of the family Derbidae, based at least partially on the context I discovered them in.  While adult derbid hoppers, like most planthoppers, are sap suckers, the nymphs of some species feed on fungi, particularly in rotten logs.

Because these hoppers are immatures, their wings have not yet developed (you can see the developing wing buds on their backs).  Adult derbids typically have long, delicate wings for hoppers.  In fact, they are noted for gathering to perch under broad leaves, a behavior which may protect their fragile wings (U Del).

I’m calling these potato monsters

Gall aphid colony in pecan leaf.

I wrote this post up back in the spring, then accidentally deleted it and was too disheartened to come back to it for months.  But these little guys are too cool to abandon forever.  The little yellow potato monsters in the photo above are pecan gall phylloxera, a relative of aphids and thrips.  They are exceedingly tiny.  So tiny that although I observed and curiously popped open the large pecan leaf galls many times while rearing my lunas, it wasn’t until I idly took a look under a scope one day that I even realized the little insects were there.

Open and closed pecan leaf galls with gall phylloxera colony.

Pecan phylloxera have fascinating, complex life cycles.  These vary quite a bit between species, but I’ll share a general example, that of Phylloxera devastatrix, probably the most damaging pecan phylloxera.  Pecan phylloxera galls are started by “stem mothers,” who inject a toxin into the plant while feeding on young tissue.  This toxin stimulates the plant to grow a gall, gradually encasing the feeding insect over the course of several days.  Each stem mother then lays eggs in her gall, which develop and feed in relative safety.  In late summer, at the end of the gall’s life cycle, the galls split open, allowing winged asexual phylloxera to disperse.  They’re not done yet.

Close up of pecan gall phylloxera and eggs.

Not content with such a simplistic, multigenerational life cycle of barely three tiers, the asexual phylloxera find a good spot and lay some eggs.  Two different sizes, just to be more special.  The large eggs hatch into sexual females, and the small eggs into sexual males.  The phylloxera mate, and the mamas-to-be seek out a nice sheltered place…where they die.  This gives the eggs a nice, cozy refuge to ride out the winter–tucked up safe in mom’s dead body.  In the spring, the eggs hatch out of their mother and become stem mothers, which disperse to find young plant tissue and start new galls, beginning the beautiful cycle of life once again.

Damn, I love nature.

More pictures:

Gall phylloxera and eggs in an opened pecan leaf gall.

Close up of pecan leaf gall phylloxera.

Underside and mouthparts of pecan gall phylloxera.

Pecan gall phylloxera nymphs are exceedingly tiny.

References:

Phylloxera gall on Pecan, TAMU

Pecan Phylloxera, Smith & O’Day

Pecan Phylloxera, OK State

Meal Time

Crab spider devouring a web-wrapped plant bug (Miridae).

Just a random picture of a crab spider with a mirid lunch all wrapped up.  Plant bugs seem to be a popular lunch item in my neck of the woods. Of course, they’re the largest true bug (Hemiptera: Heteroptera) family, mostly herbivores, and conveniently snack-sized.

Thorn Mimics & Other Freaks of Nature

A thorn-mimicking treehopper on a branch (Membracidae).

Membracids (commonly called treehoppers) are one of my favorite bugs–and one of the few smaller insects that I will consistently take the trouble of snagging for my collection.  At the start of my journey into entomology I can recall being deeply impressed by some thorn-mimicking treehoppers pointed out to me on a branch.  They look like thorns!  They run around the branch and try to hide from you!  They hop!  What’s not to love?

Oh, and a good number of membracid nymphs have mohawks.  That’s pretty freaking adorable, right there.

These little guys are incredibly diverse.  Here’s a picture that’s not mine:

Variation in treehopper morphology (Photo credit: Prud’homme et al 2011).

Not only are there thorn-mimics and brightly colored aposematic hoppers, but also feces and even ant-mimics.  The treehoppers that look as if they have sprouted entire mutant ants from their back are some of my favorites.

Now, I was taught that this structural diversity came from variations in the pronotum, but it turns out membracids are even more interesting than that.  Recent research has provided evidence that the helmet structure is actually a novel appendage, entirely unique to the genus.  This structure is apparently something like a modified third wing, the presence of which may be a result of mutations to the Hox gene complex.   (This is the same group of regulatory/developmental genes that can cause mutant flies to sprout legs in the place of antennae and such.)  A very cool example of evolution in action!

See also: Ants & Hoppers

The Mummy – Aphids and Parasitoid Wasps

The remains of a parastized aphid ("mummy") complete with parasitoid escape hatch.

My labmate Collin found mummies in his aphid colony.  It was kind of exciting, although maybe not up to horror movie standards.  Mummies are what happen to aphids when a parasitic wasp injects them with an egg.  As the wasp larva grows inside their bodies, feeding on their hosts, the still living aphids swell into pale, bloated, unmoving forms on the leaf surface.  Eventually, adult wasps burst from their hosts, leaving behind the kind of gruesome sight pictured above.

Close up of cotton aphid (Aphis gossypii) feeding on a cotton leaf.

For comparative purposes, here are pictures of a healthy, live aphid, as well as the shed skin of an aphid following a molt.  For a frame of reference these guys are about a millimeter or two long.

Cotton aphid exuvia (cast off exoskelton) on a cotton leaf.

Special thanks to Collin McMichael for helping me with the digital microscope photography.  And thanks also to someone who featured a how to on manual focus stacking in photoshop a while back.  I cannot find this post again for the life of me.  There was a picture of an ant with a parasitoid I think.  It was awesome.  I have been wanting to try this technique for a while, so it was fun to experiment.  I should probably get a shot with the legs in better focus in the future.

(Extremely) Flat Bug

Adult and nymph flat bugs on bark underside (Aradidae).

One interestingly little bug family that I have occasionally stumbled across while peeling back bark is the flat bugs, family Aradidae.  As their name suggests, these bugs are notable for their extremely flattened body morphology, an adaptation to their lifestyle under bark and in crevices of wood.  These guys are hard to spot, being cryptic both in body and lifestyle, but, as an example of morphology pushed to the limits, they are impressive to observe.

A flat bug shown on a finger for scale (Aradidae).

Because these bugs are of little economic importance (they are rarely agricultural pests) little research has been done on them.  Nonetheless this is a diverse group which is found worldwide.  Most flat bugs feed on fungi in decaying wood, and some are attracted to the pheromones of bark beetles, which may help them to locate food sources.  These bugs tend to be found in gregarious groupings.  Probably the best gathering of information that I have found on aradids is Steve Taylor’s info page, complete with some great pictures.

Side view of the aptly named flat bug (Aradidae).

Gender Identity – Milkweed Bugs

Distinguishing markings on the abdomens of a female and male milkweed bug (Lygaeidae: Oncopeltus fasciatus).

So one random factoid I encountered while researching milkweed bugs last week is that you can distinguish males and females by the markings on the underside of their abdomens.  Females have a black stripe and two black dots, while males (the smaller sex) have two black stripes.  I didn’t have a male to draw comparisons against last week, so I tracked down a neighboring lab colony of milkweed bugs and sure enough, boys and girls!  (Thus resolving any future crises I may have involving the gender identification of milkweed bugs.)

I had originally wanted to photograph a mating pair, but apparently they found being repeatedly flipped onto their backs disruptive.  I finally resorted to sticking them in the freezer for a few minutes, after which they gave a very good impression of being dead (slightly too good an impression).  Luckily they eventually perked back up and I got a few photos.

Milkweed Bugs

A female milkweed bug (Lygaeidae: Oncopeltus fasciatus)

I love Texas–when I’m not complaining about the heat–because you can find insects virtually year round.  In December I was playing with earwigs and now it’s January and already the fire ant mounds are popping up everywhere like spring flowers.  (Working with fire ants has severely warped my perceptions of this event.)  I found this large milkweed bug (Oncopeltus fasciatus) sunning itself today in the balmy 70 degree weather.  Bugguide.com lists these fellows as active only from May to October, at least in North Carolina, which is apparently because North Carolinians have an odd phenomenon known as ‘seasons.’

Ventral view of a female milkweed bug (Lygaeidae).

Milkweed bugs belong to the true bug family Lygaeidae, the seed bugs.  Like other members of the family, milkweed bugs make their living feeding on nutrient rich plant seeds, in this case usually the seeds of the eponymous milkweed plant.  (Yes, this entire previous sentence was an excuse for me to use the word ‘eponymous’.)  They use their tubular mouthparts to pierce the walls of seed pods, feeding on the seeds within.

Like that other famous milkweed feeder, the monarch butterfly, the bright, warning coloration of milkweed bugs warns predators that these bugs sequester toxic compounds from the plant in their bodies, making them distasteful.  Milkweed bugs can be fed a variety of other seeds, although interestingly they habituate to food types and it often takes several generations for them to make a switch.  Milkweed bugs in the lab are generally fed sunflower seeds, shelled or cracked since their mouthparts can’t pierce the harder husks.

In the Life of an Ant

Elongate twig ants (Pseudomyrmex gracilis) nesting in a windowsill

Last spring I had the pleasure and entertainment of some of my favorite ants setting up camp in the exterior lining of my front window.  Pseudomyrmex is one of the groups of ants that truly displays the close relationship to wasps in their form.  I have never been stung, but I’m told it’s fairly painful.  Luckily, like many insects, they are not particularly aggressive towards humans unless truly provoked.  In general these ants responded to my getting too close with the camera by dropping off the wall to the ground, a fairly common escape behavior.  It was fun to watch the workers as they hauled home their catches and try to identify the prey item.

A twig ant (Pseudomyrmex) preys on a plant bug (Miridae).

Mirids (Miridae), commonly(and rather vaguely) known as ‘plant bugs’ were all over the place at the time, and seemed to be a fairly common catch.  My personal favorite was the small critter seen below, whose large curved jaws identify it as a neuropteran larvae, one of the net-winged insects.  It’s likely a lacewing larvae, but–as a number of antlions had set up pits in the sand below the window–I am personally fond of the idea that this is a case of ant eating antlion.  Sweet revenge!

A twig ant returning to the nest with its neuropteran prey.

Predator or Prey

A leaf-footed bug nymph in profile (Coreidae).

Look at the picture above and the one below.  You may notice a resemblance to some of the insects I’ve talked about in my most recent posts.  However, despite their similar appearance these bugs are actually two different types of insects from two very different families.  The insect above is an herbivorous leaf-footed bug (Coreidae), while the bug below is a carnivorous assassin bug (Reduviidae).  In fact, many leaf-footed bugs and assassin bugs in the field bear a striking resemblance to each other.

Assassin bug peering over a leaf (Reduviidae). The stridulatory groove can be observed on the prosternum.

How to tell them apart?  Those same sucking mouthparts that classify them both as hemipterans.   These beaks, or rostrums, may both be designed for sucking fluids but they also tell us something about the kind of food each bug eats.  Leaf-footed bugs, and other coreids are exclusively plant eaters.  Assassin bugs and other reduviids are exclusively predators.  As a rule of thumb, the beaks of herbivorous insects are longer than those of carnivores.  This is because most herbivorous insects need to pierce deep down into the tissue of plants to reach the sticky sap.  Predatory insects, on the other hand, have short stabbing knives of beaks to quickly pierce their prey and inject toxic digestive chemicals.

As you can see, the leaf-footed bug in the first picture has a beak reach most of the way down it’s body.  The beak of the assassin bug in the second picture is much shorter.  In fact, among reduviids this beak is the most diagnostic trait for identification.  The beaks of reduviids tuck under their heads and fit into a small notch in their sternum, or chest, called a stridulatory groove.  Reduviids can rub their beaks across the rough surface inside this groove to  create a rasping noise (stridulation) to warn off predators.