Fighting ants and Freeloading flies

Harvester ants fight while a freeloader fly awaits the spoils of war.

I snapped this picture of fighting harvester ants in Arizona, and it wasn’t until I could see the images under the camera’s magnification that I was able to notice a few cool details.  First, please note that this is not in fact, two harvester ants fighting, but rather two and a half ants fighting.  These ladies are tenacious in battle.  Second, as I glanced through the series of pictures of this encounter I realized that one of the ants had a passenger.  (Or, perhaps, was showing off her lovely living hat.)  Paul Lenhart clued me in to the really interesting bit of biology playing out here.

Harvester ant tug-of-war, with freeloader fly looking on.

The fly riding out the fight atop one of the ants’ heads belongs to the family Milichiidae, the freeloader flies.  These very small flies are best known for the members of the family which make their living as commensals or kleptoparasites of predatory insects.  The adult flies hang out near predators, such as spiders or assassin bugs, and sometimes even ride along with them (attendance) awaiting the opportunity to sip up fluids exuded by wounded prey.

Freeloader fly rides out a fierce ant tussle.

Much like mosquitoes and blood-feeding, in many species only the female exhibits this parasitic behavior, presumably because she needs a high protein diet to lay her eggs.  Some myrmecophilous species (ant-loving) have developed such a specialized relationship they even directly solicit ants for food via regurgitation or have larvae tended by worker ants in the nest.  In some cases this interaction takes the form of a “mugging.”  The flies pursue an ant, and, if they can successfully grab hold of the head by gripping the end of the antennae, the ant will then freeze and the fly can extend its proboscis into the ant’s mouth and trigger the regurgitation reflex (Wild & Brake, 2009).  As always, Alex’s pictures are impressive, so if you can’t access the paper figures definitely check the subset in his gallery.

• See also: Gruesome leafcutter ant battle (video)

Flying Robot Bugs

House fly at rest.

A house fly takes off vertically into the air.

While snapping pictures of a fly perched beside me during a long car drive I caught a shot of it in mid take-off, as it launched straight up into the air.  I’d never given a lot of thought to house fly flight dynamics before, except perhaps during miserably failed attempts to swat them.  Attempting to learn more on the topic  led me to a fascinating article discussing the use of insects to develop flying nano-robots, aka Micro air vehicles.

Obviously, I want one of these.

A tiny, insect-inspired flying machine (photo: Wood 2008).

But instead of talking about tiny flying robots being harnessed for military purposes I thought I’d tell you some boring fascinating stuff about insect flight muscles.  The oldest insects (Paleoptera: dragonflies, damselflies, and mayflies) have muscles directly attached to the base of the wing (direct flight).  The fore and hind wings are operated independently, allowing for excellent mobility and maneuvering.  All later insects (Neoptera) have muscles that attach to the exoskeleton, and move the wings indirectly by changing the shape of the thorax (indirect flight).  Generally, the wings function together as a single unit.

Because I was bored, I diagrammed the muscles involved in indirect flight:

The dorsoventral muscles contract, pulling down the top of the thorax and causing the wings to rise.

The dorsolongitudinal indirect flight muscles contract, arching the top of the thorax and causing the wings to beat downwards.

If you have trouble visualizing how flexing the exoskeleton in these directions could lead to the appropriate wing movements, I recommend this simple experiment:  Take a tennis ball, and stick two pins in it to represent the wings.  Squeeze the tennis ball from top and bottom (dorsoventral muscles) and from front and back (dorsolongitudinal indirect flight muscles) and observe the movements of the pins.  We did this back in my Insect Physiology class, and it makes for a very striking visual tool.

Wikipedia also has two very useful animations (the direct flight diagrams is mislabeled, though, so mind your links):

• Direct Flight
• Indirect Flight

The flower and the fly

Pretty things.

I’m in the middle of prelims and also a rather prolonged fever but I thought I’d check in before November ended.

Plus now I can stare at this pretty flower and the stripey fly I saw in Argentina.  I don’t know what kind of fly it is but it’s very striking.  Looks like it’s a nectar feeder.  VanEngelsdorp and Mexner recently estimated the global value of insect pollination at US$ 212 billion, or about 10% of the global value of agricultural production (2010).  There, I even included an insect fact.

Shh, only pretty flower-flies now.

*edit* Thanks kindly to Morgan Jackson and Joel Kits in the comments for identifying this as a bee fly (Bombyliidae) in the genus Poecilognathus.  Bee flies are really really cool little flies whose young generally parasitize other insects.

March of the Zombie Flies

OHGODTHEY’RECOMING

I don’t actually know what was going on with these creepy decayed blowfly carcasses.  If you haven’t noticed, that top one is missing its head and the bottom fly’s wings and eyes are flaking away.  I found these and a half dozen more stuck fast to a sandy overhang by the Red River this past Entoblitz.   It kind of looked like a still scene from Attack of the Zombie Flies.

Why were they congregated there?  What killed them?  Personally, I suspect a bacterial infection or pathogenic fungi.  Many such parasites can actually alter the behavior of their hosts, causing them to seek out situations and habitats that help the pathogen grow better or infect new hosts.  There’s even a little bit of evidence that pathogens may be able to manipulate human behavior: a few studies indicate that people infected with Toxoplasma gondii (often carried by cats) may be more risk-prone.  The protozoan parasite may alter the behavior of its intermediate rat host to increase the chances of predation by cats, allowing the parasite to complete its life cycle (Berdoy et al 2000).

So, anyway, I’m going to go with mind-controlling fungal infections on this one.

That, or aliens.

Thoughts?

When Bugs Bite Back

A horse fly perches on a tree.

The family Tabanidae derives its name from the latin word tabanus, meaning “horse fly.”  I’ve noticed that observing which orders and families of insects take their latin names from actual latin or greek words for the insects (e.g. roaches, lice, ants) tends to give an idea of which insects have historically made the biggest nuisances of themselves.  Chalk these biting flies up on that list.

I like horse flies because they turn the tables on entomologists.  I have had several experiences wherein it was unclear just who was hunting whom.  It generally winds up with me flailing wildly with my net while running in circles to try to stay out of reach of the fly.  The lady fly is, after all, on the lookout for a tasty blood meal to grow her eggs with, a meal she will secure by slicing open a wound with scissor-like blades on her proboscis.  She’s also way faster and more agile than me.  It’s extremely disconcerting.

Horse and deer flies can be distinguished from other flies by their large eyes, their enlarged third antennal segment, and by the pair of “Y” shaped wing veins that enclose the wing tip.  Male horse flies, which do not blood feed, generally have eyes that meet in the middle of the head, unlike the lady in the picture above, whose eyes are set apart.

As a side note, my backyard is suddenly full of stable flies, a house fly-like muscid fly which rabidly attacks my ankles when I venture outside.  Ow.  If I’m overcome with masochism I’ll even try to get pictures for y’all.

Nooooooooo (Attack of the Carpet Beetles)

Bee fly with eyes eaten out by dermestids.

Here’s a sight no insect collector wants to encounter in the collection boxes.  I was sorting a mixed box of pinned specimens when I found that this fuzzy bee-mimicking fly had met a second untimely fate  (the first being the fate that led him to be pinned in my collection).  As you can see, the large bulbous eyes that occupy most of the bee fly’s head are, um, no longer occupying.  In fact, they’ve been rather neatly eaten away.  Apparently, bee fly eyes are delicious.

Dermestid damage in an insect collection.

With mounting horror I sifted through the collection box and found all the signs: tattered insects, scattered frass, and (the smoking gun) cast off larval skins.  One hairy skin stuck to the wing of a tiger moth whose hollowed out abdomen had apparently made a tasty treat.

Cast off exoskeleton of a carpet beetle larva (Dermestidae).

Dermestids.  Oh, joy.  Is there any insect that is more unwelcome in an insect collection?  (Actually, my friend Paul had an unpleasant experience with a voracious colony of fire ants, but that’s another story.)  These guys, often called carpet beetles or hide beetles, are dietary specialists on dry, high-protein organic materials.  Everything from dandruff to leather to natural fiber carpeting may become their food source.

Carpet beetle close up (80 times magnification).

This not only makes these beetles a damaging household pest, it makes them both dangerous and very useful to to people who work with dead things.  When they’re not uninvited guests, dermestid beetles are frequently used to “clean” skeletons, removing hide, flesh, and all.  If you’ve every watched the show Bones, you may be familiar with Zack’s colony of “flesh-eating” beetles kept for this purpose.  (Zack: You can’t kill them.  They have names.)

The scaled exoskeleton of a varied carpet beetle (Anthrenus verbasci).

These particular guys were varied carpet beetles, a fairly common indoor pest.  Examining them under a scope reveals that these tiny, nondescript little blobs are quite striking.  The beetles are covered with tiny, multi-colored scales in orange and white and black and their rotund little bodies, with legs retracting into grooves, mak them look something like carnival balloons.  Pretty adorable for something that can leave a trail of carnage and destruction in its wake.

The legs of the carpet beetle can tuck back into grooves.

Luckily, the damage was fairly limited (the two specimens pictured here were by far the worst off) so I can consider the whole incident with amusement and interest.  The pictures were fun.  The collection?  Is cycling through the freezer.  Only dead bugs welcome in these boxes.

Pointed carpet beetle with hand for scale. (Thanks to Loriann Garcia for providing the pointed specimen for the impromptu photo shoot.)

—

A/N:

Can we talk for a minute about the fact that I took all these pictures with my cell phone?  Forget hoverboards; we are living in the future.  Right now.

It would never have occurred to me to point an iPhone down a dissecting scope without Alex Wild’s recent post over at Myrmecos.  Clearly, I had tons of fun with this.  I highly recommend it.

Maggot Art Live

Here’s a video I put together of the “maggot art” I talked about earlier this week.  Enjoy!

 

Maggot art, etc.

Maggot art with Chrysoma rufifacies, the hairy maggot blow fly

Two new pages up today in the Techniques section.

I’ve started a collection of cool insect-related techniques as I happen across them around the internet:

Techniques from Around the Web

I also had a lot of fun doing maggot artwork at an outreach event and I put together a “how to” post on that.  Check it out!  The pics are all taken with my iPhone but they turned out great:

How to Paint with Maggots

Maggot art makes a nice item to sell or give away at events, and it also provides a fun, hands-on outreach opportunity that people of all ages can enjoy. It’s great to watch people go from “Ew!” to “Ooh!” as they see a disfavored insect make something pretty and interesting. Don’t forget to talk to people about the role of maggots in the ecosystem, the life cycle of flies, and the usefulness of maggots in cleaning wounds. The maggot artwork also makes for a nice souvenir to take home, and hopefully encourage people to talk about what they learned with even more people.

Pollinator

Pollen-covered fly feeding at a flower (Presidio la Bahia, TX).

I noticed recently that when I see pictures of flowers without bugs on them I find myself thinking that they are lacking, as if the photographer has left something out of the composition.  Yes, that’s a lovely flower– but it would be more interesting with bugs.

Look how pretty that fly is up there.  Much better.

I can’t see the subscutellum, but I’m going to place this fly as a tachinid anyway, using my go-to “look how bristly it is” method.  I’m a lazy taxonomist.  Tachinidae is an interesting family, as its members are parasitoids of other arthropods.  House flies and fruit flies lay their eggs on rotting meat or fruit.  Tachinids lay their eggs on or in another living arthropod (most commonly caterpillars).  The young maggots feed on their living host from the inside, Alien-style.  Adults live more mild-mannered lives, feeding on flower nectar, pollen, decaying material, or nothing at all, until the time comes to find a host for their young.  A beautiful, science-fiction circle of life.

Tag:  Bugs on flowers

Bloodsuckers

A mosquito fills her belly with a blood meal.

One weird aspect of becoming an entomologist is that my basic, instinctive reactions to many events has changed.  I’ve mentioned before admiring cockroaches at a restaurant, and  my own particular research has gotten me quite cozy with fire ants.  Apparently, I will also pause to photograph the mosquito sipping blood from my arm as well.  (Bonus oddness:  While I was photographing the mosquito above, a fellow grad student called dibs on it for his collection.)

Mosquitos are flies (order Diptera) belonging to the family Culicidae. The family name is derived from latin ‘culex,’ basically referring to little flying insects  (think ‘midge’ or ‘gnat’).  In their adult form mosquitoes are primarily nectar feeders.  Only female mosquitoes take blood meals, and then only in order to nourish developing eggs.  In the picture above, you can see the fine piercing stylet being used to withdraw blood, as well as the protective sheath which has been folded back in a U-bend.

The mosquito also has the honor of being the first insect I saw on my trip to Argentina last winter.  It was waiting in the rental car for us:

Mosquito in car window (Argentina).

This proved to be especially portentous since Argentina was rife with concern over dengue fever, a dangerous mosquito-borne disease that has been making a comeback in the urban centers of Argentina.   The signs we saw most often carried the slogan ‘entre todos contra el dengue’  (all of us against Dengue), and directed people to eliminate standing water (where mosquitoes breed) and be alert for symptoms of the fever.

Posters warning of mosquito-transmitted dengue fever in Argentina.

In fact, the mosquito is the deadliest animal in the world, causing (through the transmittance of disease) more than 2 million human deaths per year.  (Oddly enough, the biggest cause of human deaths by large animal may be the hippopotamus.) Just as diseases can be transmitted from human to human by the use of unsterilized needles, the mosquito’s needle like proboscis can vector diseases from person to person, all without any harm to the mosquito itself.

Mosquito feeding in Argentina