(Describer) Titles: The Bug Chicks, and Solpugid Productions, in association with Texas A and M University. Insects and Human Society.

This episode is of great importance to me.

(Describer) A dog.

Fleas are a living nightmare for me and my four-legged brethren. Just thinking about them makes me itchy. Learn about them, please. We depend on you for help.

(Describer) Different insects are shown: including a small green one with wings, hundreds of tiny ones swarming a worm, one with transparent wings climbing a tree, a thin green one looking around, two with translucent white wings, and one crawling on a green leaf before flying off. Titles: The Insect Orders.

[Morgantj plays "Cafe Connection"]

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(Describer) Order Siphonaptera : Fleas. Taxonomy. Petting the dog....

Fleas are in the order Siphonaptera. "Siphon" means tube, and "aptera" means wingless. Now, fleas share a common ancestor with the snow scorpionflies. Remember those ones with the tiny rudimentary wings? And being wingless is an adaptation to the habitat that these animals live in. So when you see "a" in front of "ptera," it means "no wings." Now, how do we remember that fleas are in the order Siphonaptera? "Siphon," like you suck gas out of your car; fleas suck your blood; blood is your life fuel. Life fuel, that's gross. And isn't siphoning gas illegal? Only if it's not your car.

(Describer) Title: Morphology.

Fleas are tiny. They're only about a millimeter to 2 1/2 millimeters long, and they're laterally flat, like a flounder. This allows them to move easily through dense hair follicles. Fleas have three stylets for mouthparts that they use to pierce the skin and suck up the blood. Some fleas, like the cat flea, have structures called genal and pronotal combs. These are rows of unmoving spines that make the fleas look like they have little beards. These spines may protect the underlying intersegmental membrane, or fleshy necks, of the insects.

(Describer) Walking the dog...

Fleas have surprisingly long legs, especially the hind pair, and they're specially adapted for jumping. In fact, some flea species can jump over 150 times their own body length. This means someone of Kristie's height could easily jump over the Washington Monument. It's an incredible feat for an animal with such tiny, little muscles. So, for years, scientists were trying to figure out if they have a different mechanism that helps fleas jump. Turns out they do. They've got a substance called resilin inside their joints. Resilin's kind of like rubber. When it's compressed, it stores a bunch of energy. When fleas jump, that energy is released in a superfast burst.

(Describer) Title: Biodiversity and Distribution.

There are more than 2,300 species of fleas in the world, and about 325 of them live here in North America. About 90% live on mammals, and the rest live on birds. Fun fact: Cat fleas are the most common flea you'll find on dogs, and dog fleas can infest cats. There are also rat fleas, which we'll talk more about later, pig fleas, rabbit fleas; and the largest flea is the beaver flea. This is a beaver flea compared with a rat flea.

(Describer) Several times bigger.

Now it is time for "Insects in the News: Charades Edition." Ooh! Are you ready, Jess? Yes! Okay, so I'm gonna give you a couple of hints, and you're gonna tell me how fleas have been in the news lately from the hints I give you. Okay. Okay. First hint...

(Describer) Kristie moves a glass of water and smacks the table beside it. The water vibrates.

Earthquakes. No. Fleas and earthquakes? What about that? You know, the fleas, like maybe there's a ginormo flea-- No, no, no. Second hint, second hint. Ready? Okay. Okay. It's layered with music.

[humming orchestral tune] ♪ Da da-da da ♪

♪ Da-da da... ♪♪ That's to a movie.

That's a theme song. Movie? I--It is--I don't know. You don't know. Okay. I was hoping it wouldn't come to this, but I'm gonna have to do a movement hint. Oh!

(Describer) She stalks around with bent arms, her hands like claws and her mouth very flat and stretched out.

[roars] aah!

I know this one! Jurassic fleas! Scientists at the National Museum of Natural History in Paris recently discovered the largest flea ever. It used to drink dinosaur blood!

[screams] aah!

(Describer) Title: Biology and Life History.

Flea larvae can live on pet bedding, carpet, and outside in the soil. When inside, they feed off of adult flea poop, which is basically digested dried blood, and pet dander. When outside, they feed off of organic debris in the soil. Now, adult fleas are obligate blood feeders, and they stay on one host for their entire life span. So how does a flea find a host once it's pupated into its adult form? Like most blood feeders, they're attracted to carbon dioxide given off by the host. They're also stimulated by vibrations in the ground when a host walks by. If they jump when they sense vibrations, it increases their chances of landing on a host.

(Describer) Title: Metamorphosis.

Fleas are holometabolous and undergo complete metamorphosis. This means they have four stages: egg, larva, pupa, adult. In complete metamorphosis the larvae look completely different from the adults.

(Describer) Title: Human Impact. With the dog...

About 62% of U.S. households include a pet. So even if people don't know a lot about entomology, they at least know something about fleas. The last time we were at the vet, we took the opportunity to talk with a vet tech about flea prevention. Will you tell us how we can protect our pets and prevent flea infestations?

(Describer) McKenzie W.:

What people should ideally do is keep their pets on a monthly flea preventative prescribed by doctors-- so, your topicals or, you know, medications--year-round because a lot of the misconceptions is that people think that it's just in the warmer months, but really it's throughout the whole entire year because they come in and lay eggs in your bedding, and in their bedding, and in your carpets. Okay. So it's really good to keep it on them year-round. Excellent. In developed countries nowadays, fleas are really a pet owner's problem, but in the past fleas played a role in some of the largest disease pandemics in human history-- the Black Death, the plague, the Great Mortality, the Great Pestilence. Whatever you want to call it, it's bad. The pathogen is a bacteria called Yersinia pestis. The host is rats, most commonly the black rat, Rattus rattus. The vector is the Oriental rat flea, Xenopsylla cheopis. Yersinia pestis is a bacteria found in rats. In the wild, the bacteria just sort of circulated between the fleas and the rats; but in urban areas, where rats were living in and around human dwellings, humans became a host as well. Add in poor hygiene, and this is how it spread so quickly. The Black Death of the Middle Ages started in Asia and quickly traveled along the Silk Road and killed millions of people as it moved west to Europe. The plague of the Middle Ages had reoccurrences all the way through the 17th century. And it's still an active disease all around the world. There are a handful of cases reported from the U.S. every year.

(Describer) Title: Collection.

Collecting fleas is really easy compared to other insect orders. Just head over to your local animal shelter or vet and ask if you can take a few off their hands. They'll be happy to oblige.

(Describer) Title: Mythology and Culture.

After all of the gloom and doom of fleas, we decided to end on a high note-- flea circuses! Okay, the phenomenon of the flea circus is said to have started with watchmakers who were trying to show how adept and agile they were, working with tiny watch parts. As the art form grew, flea circuses were broken into two kinds: those with live fleas and those who mimed fleas. OMG, I have always wanted to do this. We are going back to your theater roots.

(Describer) With a tiny tent and ferris wheel...

So we were totally gonna make a flea circus for you guys. A live one, not a dumb mimed one. We even got fleas from the local animal shelter and everything. But they all died. Well, there was one that was alive, and we tried to keep it alive by feeding it on Kristie's arm, but then we found out that a guy three hours down the road contracted plague, so we thought it might be a bad idea. You thought it was a bad idea. Safety first, Kristie. Anyway, Kristie pricked her finger and smeared her blood all over a microscope slide to keep it alive. But all it did was the backstroke, and then it died. Kris, is there anything I can do to cheer you up? You can maybe sing the fun song. [humming "The Man on the Flying Trapeze"]

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(Describer) Kristie moves a little toy car and pretends a flea walks on their little tightrope.

[both humming "The Man on the Flying Trapeze"]

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[imitating jumping sound] pow!

(Describer) She pretends it hops onto the ferris wheel.

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(Describer) Titles: Writen and prodced by Kristie Reddick, Jessica Honaker. Videographers Kristie Reddick, Jessica Honaker. Accessibility provided by the US Department of Education.