Sand Fleas Are Real! (But They’re Not What You Think They Are…)

June 15, 2016
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Well, it’s summer time again and millions of people will be spending lots and lots of time outdoors. They will go to the lake, they will go to the beach, they will have picnics and barbecues and luaus. All the while, they will be joined by many unwanted guests — of the arthropod kind!

Many people think about the summer in Houston a little like this:


Cartoon by Gary Larson

Bugs, or arthropods, are everywhere, and our favorite time of year to play outside just happens to be the prime of most of their little lives. Every year I hear horror stories about bugs, particularly about the beach. Perhaps it’s because creatures that inhabit such an environment are so foreign to us. The oceans are the earth’s last known frontier, and animals that live inside or near it might as well be aliens to most of us!

We are so lucky to live in the age of having information at our fingertips. Want to know something? Just Google it! The almighty “internets” can’t be wrong! But anyone is allowed to write anything about any topic they desire, so the almighty internets are sometimes wrong.

If you want to go to the beach, and you Google, say, sand fleas, you’ll very likely read articles that will keep you away from the beach for good! So allow me to fill you in on some of these mysterious critters that call the beach home.

Arthropods are the most abundant and successful animal life-form on the planet and they can be found surviving and thriving in almost any environment. Naturally, they enjoy the beach as much as we do. The warm temperatures, that nice ocean breeze… If you walk along the beach at any time of day, especially the morning or evening, you will see all sorts of activity — mussels that have been unearthed by the waves wiggling back down into the sand, little crabs skittering around, flies buzzing about, and perhaps seaweed washed ashore, covered in small creatures.


Sand hopper, a crustacean in the order Amphipoda and the family Talitridae. Many different genera have a similar appearance.

These herbivorous creatures are most likely what we sometimes call “sand fleas,” though they are actually land hoppers or in beach environments, sand hoppers. You may have heard terrible things about these little guys, that they suck your blood, leaving awful welts, or even that they burrow into your skin to lay eggs. None of these things are true of sand hoppers. They are crustaceans, cousins to the insects, with five to seven pairs of legs and two pairs of antennae. Other well-known and delicious crustaceans are crabs, shrimp, lobsters and crawfish. Sand hoppers belong to the order Amphipoda and sort of look like a cross between a giant flea and a roly-poly. They mostly live in water, but some species are terrestrial and live in damp areas. They are scavengers that feed on rotting organic matter, so a nice pile of washed-up seaweed looks really good to them. They can hop, but that’s where the similarities with actual fleas begin and end! They do not suck blood, and in fact they want nothing to do with you. If you approach them, they will jump away, the obvious origin for their common name.


Mole crab (Emerita analoga) digging in the sand.

Another crustacean incorrectly called a sand flea is a tiny little crab called a mole crab — AWWWWW!!! (Oh wait, am I the only one who thinks it’s cute?) They are filter feeders, meaning they filter plankton from seawater. They burrow down into the sand where the waves break on the shore, and they’d also prefer to stay away from humans.


True sand fleas are native to central and south America and Africa. They lay their eggs in mammalian flesh, leaving a bad infection on the hands and feet.

Now, the true sand flea, the one that is an actual flea, is a nasty parasitic insect. But, they don’t inhabit North America. You can, however, find them in Central America, South America and Africa. Sand fleas, also called the chigoe flea, are the smallest known flea species (about one millimeter across). They burrow into mammalian skin to feed and may cause an infection known as tungiasis. But this is only really an issue in areas of poor sanitation. So please folks, don’t worry yourself over sand fleas.

2006 Frank Collins Leishmaniasis is transmitted by the bite of infected female phlebotomine sandflies, injecting the infective stage (i.e., promastigotes) from their proboscis during blood meals.  Promastigotes that reach the puncture wound are phagocytized by macrophages ,and other types of mononuclear phagocytic cells, and inside these cells, transform into the tissue stage of the parasite (i.e., amastigotes), which multiply by simple division and proceed to infect other mononuclear phagocytic cells.  Parasite, host, and other factors affect whether the infection becomes symptomatic and whether cutaneous or visceral leishmaniasis results.  Sandflies become infected by ingesting infected cells during blood meals.  In sandflies, amastigotes transform into promastigotes, develop in the gut, (in the hindgut for leishmanial organisms in the Viannia subgenus; in the midgut for organisms in the Leishmania subgenus), and migrate to the proboscis. See PHIL 3400 for a diagram of this cycle.

Sand fly (Phlebotomus papatasi), but the name can refer to any species of biting, blood-sucking insect found in sandy environments.

The only arthropods that may feed on you at the beach are things that will feed on you everywhere else, mosquitoes, and biting flies (sometimes called sand flies). Unfortunately, I don’t have much to say in defense of mosquitoes you’ll find at the beach, especially salt marsh mosquitoes (Aedis sollicitans), they’re kind of the worst! They’re large, fast, and pretty relentless. They breed in inter-tidal pools of brackish water and the eggs can lay dormant for years waiting for water!


Sand midges beside a dime and a pencil point to show their relative size.

Other flies that feed on you at the beach are small midges, commonly known as “no-see-ums” (yes, really), and just like mosquitoes, only the females feed on blood in preparation to lay eggs. The most you’ll get from these are classic signs of a bite, small red bumps that itch. A good bug spray containing DEET, or even some that contain effective essential oils such as lemon and eucalyptus, are effective at repelling all of these types of insects.

So if you’re heading to the beach this summer, don’t forget the sunscreen, don’t forget the bug spray, but leave the entomophobia (fear of bugs) at home. You have nothing to fear!

Authored By Erin M Mills

Erin Mills received her undergraduate degree in Entomology from Texas A&M University in 2004, and after a short tour of the pest control industry, joined HMNS as the Cockrell Butterfly Center's Insect Zoo Manager in 2005. Over the years she expanded the butterfly center's live arthropod collection, developed the ever popular "Bugs on Wheels" outreach program, and continued to establish her role as HMNS's insect expert. In October of 2016, she achieved her long time goal of becoming the Director of the Cockrell Butterfly Center and in January of 2021, she joined the team at HMNS Sugar Land as the Director of Nature Programming. Erin leads hikes in Brazos Bend State Park and provides fun, hands-on nature-based experiences at HMNS Sugar Land. As a Board Certified Entomologist, Erin has extensive knowledge of insect identification, ecology, plant relationships, husbandry, really any insect-related topic!

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