Archive | June, 2012

June Taxonomy Fail

29 Jun

Here’s another Taxonomy Fail for your edification and/or entertainment.  I’m not sure who first mislabeled (or at least, mis-described) this image, but it pulls up on a number of blogs and sites with the erroneous story attached.

I present:

“Mantis Cannibalism Eating Mate”

…she’s eating a grasshopper.  They *are* bother orthopteroids, but I don’t think it counts.

via Web Ecoist: Three Mate-Eating Animals

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Wiggle Wiggle Wiggle

25 Jun

Here’s one more picture of the mama wolf spider from last week that I kind of liked even though it was taken through plastic of the container:

Lycosidae mother wolf spider with babies on back.

Also, so that you can enjoy the full effect I made a little animated GIF for y’all to enjoy:

Wiggle wiggle wiggle

Spider Piggy-Back Rides

22 Jun
Lycosidae wolf spider mom with eggs

Wolf spider mother with egg sac.

I picked up this large mama wolf spider with her egg sac while out doing field work.  The trip home apparently disturbed her, because I was disappointed to see she dropped her egg sac and apparently abandoned it.  Then a few days later it vanished.  Then she constructed a refuge of webbing coated in dirt and debris and closed herself in.  A few more days later I noticed she had an egg sac again–and it was bigger than ever.   Intrigued, I sent the picture above to friend and former post-doc in my lab Shawn Wilder.  Shawn introduced me to working with fire ants and also happens to have done his Ph.D. work on sexual cannibalism in wolf spiders.

Shawn had this to say:

Beautiful spider.  It looks like the genus Hogna, most likely Hogna carolinensis (they’re one of the more common big Hogna in Texas).   I studied Hogna helluo for my Ph.D. but they’re not quite as pretty as carolinensis because helluo doesn’t have the mottling on the legs.
That’s typical Hogna behaviour.  They will build a silk-lined burrow and will eat their egg sacs if they lose sight of them and refind them.  It looks like she is trying to warm up her egg sac in the sun. That’s a mega-huge egg sac she has.  It should be very fun when the babies crawl out and onto her body because when there are tons of babies the mom has to use her pedipalps like windshield wipers to keep the babies away from her eyes!
I had managed to completely forget that wolf spider mothers carry their babies around on their backs so I was pretty psyched.  And mama spider delivered this week.
Lycosidae piggy back rides from mom.

Mother wolf spider with a back full of baby spiders.

Shawn also pointed out that the spiderlings don’t need to eat at this point.  For a week or two they ride around on their protective mother, clinging to special barbed hairs, and then gradually begin to disperse.  Every so often a few spiderlings will drop off and walk away from the mother, providing a very effective way for the young to disperse over a wide area in nature.  Of course, if sufficiently disturbed the spiderlings may scatter early–probably accounting for urban legends of wolf spiders that “explode into little spiders” when stepped on.

Lycosidae spider covered in little spiders.

Close up of mother wolf spider carrying babies.

Lycosidae newly hatched wolf spiderling on finger.

One of the spiderlings explores a finger.

Lycosidae Baby Wolf Spider

Newly emerged wolf spiderling under 80x magnification

Beetles and Parental Care

15 Jun
A bess beetle and its larvae in a rotting log.

A bess beetle tends larvae in the interior of a rotting log (Photo courtesy Paul Lenhart).

A few weeks back I did a post on bess beetles, and their fascinating social structure.  These beetles live together in family groups, communicate via an elaborate vocabulary of squeaks, and cooperatively care for the developing brood.  Paul Lenhart recently snagged this awesome photo of an adult beetle with a group of larvae and was kind enough to let me share it with y’all here at 6legs. I thought I’d take the opportunity to do a bit more research and elaborate on what I learned last time.

Initially, a male or female beetle finds a rotting log, and begins hollowing out a tunnel.  Later the beetle will accept a mate, following an elaborate courtship ritual complete with specific acoustical signals.  The mated pair then cooperates on the tunnel and defends it fiercely from intruders.  A clutch of about 30 eggs is laid in a nest of finely ground wood in the tunnel.  When the eggs hatch into larvae, the parents cooperate to feed them specially prepared food–specifically wood which has been pre-chewed, passed as feces, and partially digested by microorganisms.  When the larvae pupate, the adult beetles construct protective pupal cases around them out of wood debris and feces.

Interestingly, young adult beetles cooperate with the parents to help care for their siblings.  The mated pair can have several clutches of eggs over the course of a year, and will often court and mate again in the nest when the initial brood has pupated.  Newly eclosed young adults require several weeks or even months for their adult exoskeletons to fully harden and darken to black.  These young adults are called “teneral” or “red” beetles, and remain in the tunnel, feeding larvae, helping to construct pupal cases, and defending against intruders.  Evidence suggests they may sometimes remain even after reaching full adulthood, assisting their parents and siblings.  Eventually, these beetles migrate from the log to join a mate and start their own family.

(Schuster & Schuster, 1985)

Luna Moths: THE FINAL CHAPTER

8 Jun

Spoiler alert: Moth form was attained.

I have to say I am both flattered and abashed that several people have taken the time to ask me what wound up happening with the luna moths I was rearing.  I hope I can distract you all from the tardiness of this post with a MASSIVE PHOTO DUMP.  Of course, most of these photos were taken with my phone, so, half credit?

A luna moth cocoon wrapped in leaves.

I left for a weekend research trip and returned to find all but one of my surviving caterpillars had spun themselves up in silken cocoons, also taking advantage of leaves, branches, paper towels, and just generally whatever was available.  Most of my cocoons were showed no further signs of life, but two remained rather terrifyingly lively–rattling and shaking around like jumping beans when disturbed.

The mystery of the empty cocoon.

Taking the advice of experienced luna moth rearer Shawn Hanrahan, I slipped paper clips into the cocoons and hung them all up in my office to await further developments.  Possibly, I didn’t think this through very well.  A  couple of weeks later I tapped one of the active cocoons hello only to discover a hollow shell with no sign of the adult moth.  Presumably it was off on an adventure in the lab.

Shed caterpillar and pupae skins.

Cast off skins inside the empty cocoon.

Of course I opened up the cocoon to check out the cast off skins.  When a luna caterpillar spins its cocoon it briefly be comes a “prepupa,” shortening and losing the ability to walk.  A few days later it sheds its skin (the caterpillar shed at the bottom of the picture) and becomes a pupa.

Cast off pupal and larval exoskeletons.

The large red-brown pupa looks much like any other lepidopteran pupa.  The developing wings and antennae are visible wrapped around the top of the pupa, while a wiggly abdomen is responsible for the movements and rattling of the more active cocoons when disturbed.  After about two weeks (unless it is overwintering) the pupa molts again, and cuts its way out of the upper end of the cocoon using serrated spurs near the base of its forewings.

Tattered male luna moth recovered after lab adventure.

I did eventually recover my wayward vagabond.  He turned up a few days later, tattered from his adventure, no longer with the energy to fly. Adult luna moths live only a few days to a week, long enough to mate and reproduce.  They survive entirely on energy stored as hungry hungry caterpillars–adult moths don’t even have mouthparts.

Row of hanging cocoons, some with exit holes.

Having learned my lesson with one adventurer, I moved the other cocoons into a glass terrarium.  Above, you can see the cocoons hung up in a row by their paperclips.  Several have emergence holes at the top.  I didn’t manage to witness any emergences; they take place early in the morning, giving the moth time to pump up its wings before the evening flight period.

Luna moth hanging from its cocoon.

The moths not only have to get their wings straightened out, they also have to void their liquid meconium–basically all the stored wastes from their transition from caterpillar to butterfly.  This staining reddish brown mess is the reason you should never hang your luna moth cocoons over carpets or anything difficult to clean.

Luna moth on cocoon with fully inflated wings.

My lunas have been emerging one by one every few days over the past couple of weeks.  They make for a fun surprise.  Male luna moths can be distinguished from females by their antennae, which have broader, more plumose fans, in order to help them detect female moths.  They also exhibit different behaviors.

Female luna moth on wall.

Upon emerging and settling in to their new form, female luna moths typically find a perch, and spend evenings emitting a special male-attractant pheromone to help potential mates find them.  Males meanwhile, disperse in search of females, whom they can detect across great distances.

Underside of a male luna moth.

In  one impressive experiment, 26% of male Indian luna moths were able to locate caged females when released more than 6.5 miles away.  What this translates to in a terrarium is that female moths left overnight will sit and chill, but male luna moths will flap around and tatter their wings to pieces….Not that I’m speaking from experience or anything.

Ta dah!

Startling conclusion: I sucessfully reared moths to adulthood! Many of them with out significant trauma!  I declare the luna moth saga a success…and move gratefully on to less time-consuming insects to rear and observe.

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