Beach Bugs!


October 12, 2010
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I recently returned from a wonderful trip to Galveston. It was so relaxing, sitting on the beach, listening to the waves and watching the birds. The beach is such a peaceful place and Galveston is very close to my heart because my husband and I got married there! Although I escaped with nothing but a few mosquito bites (my husband was not as lucky!), I got to thinking about bugs at the beach and the horror stories I have heard. I’ve heard about sand flies, sand fleas, sea lice; all kinds of crazy stuff. I decided to do a little research to see what was true and what was nothing but beach bug lore. I was absolutely shocked at some of the things I read, especially when Googling “sand fleas”! Most of the things I found were contradictory, inaccurate, and just plain ridiculous! The biggest problem seems to be the confusion between all of the common names. People in different parts of the world may refer to the same organism as several different things. That’s why scientists use Latin scientific names that are consistent across the world. So, here it is, the skinny on some of those beach pests we all hear about, what you should worry about, and what is no big deal!

Sea Lice

she don't use jelly
Creative Commons License photo credit: brainware3000

Well here’s a misnomer for you! I’ve never even heard of sea lice, but one of my co-workers mentioned them while I was researching. Many of you may have heard of them because apparently they can be quite a problem! It’s a misnomer because the real sea lice are tiny crustaceans that live in the ocean and feed on certain types of fish, but don’t bother humans at all. What we call sea lice are actually larvae of jellyfish that float around in clouds in the ocean. Although they are tiny, they still possess those nasty stinging cells or nematocysts. If you’re swimming in the ocean, they can become trapped between your bathing suit and skin. This is when you can be stung. The stings cause intense itching and burning which result in a rash with small raised blisters.  The rash can last anywhere from two days to two weeks, but most of the time they go away with no medical attention necessary, just lots of cortisone cream and Benadryl! Sea lice are common along the gulf coast, the Caribbean islands, Mexico and South America. Most beaches have warnings if the waters are heavily infested. The season for these pesky baby jellyfish usually runs from April through August.

Sand Fleas

It took me forever to get to the bottom of this one. I asked people I knew if they’d ever been bothered by what are known as “sand fleas”. The general consensus was, no. I read some of the most ridiculous things, however. I read that they attack your feet and burrow into your skin. I read that they attack fish and kill them. I read that they are crustaceans with wings, that feed on seaweed and also suck blood, but only from your feet. What?!?! So, this is what they really are. The common sand flea (Orchestia agilis) is an amphipod, or a small, terrestrial, shrimp-like crustacean. They burrow into the sand and they feed on decaying plant and animal matter that washes up on the shore, especially seaweed. They do not want anything to do with people. They obviously are not fleas, not even insects. However, they jump, similar to the way fleas do and they live in the sand, so hence the name sand flea. They are found all along the Atlantic coast, so you’ve probably seen them before. There is a more malicious animal that sometimes goes by the name sand flea, but more often is referred to as the chigoe flea. Tunga penetrans is actually a type of flea, but they are not like the more common cat flea that bites our domesticated pets. They are the smallest known species of flea. The chigoe flea lives in soil and in sand. They feed on the feet of warm blooded hosts such as humans, dogs, cattle, sheep and mice. When the female is ready to reproduce, she will burrow into the skin of the host, which is where she stays until after she releases her eggs, in about two weeks. After this, she dies and is sloughed off with the skin of the host. They can jump no higher than 20 centimeters, so they usually burrow into the foot or ankle. So, this is a little creepy, but don’t worry, they’re only native to the tropics, such as Central and South America.

Sand Flies

Female horse fly
Horsefly
Creative Commons License photo credit: Radu P

This is a pretty general term that can really refer to any biting fly you would encounter at the beach, besides a mosquito. This could even be a type of horsefly that is associated with that type of habitat. Most commonly, the name sandfly refers to flies in the family Ceratopogonidae. These are small biting midges, only 1-4 millimeters in length that live in aquatic habitats all over the world. Like mosquitoes, it is only the female that sucks blood to get protein in preparation for laying her eggs. The bite itself is too small to feel. It’s not until later when your skin starts to react with the proteins in their saliva that you start to feel the itch.  Because they go unnoticed, they can bite you a lot, that’s why they are such a pest! Bug spray is sufficient protection against these flies, but I never wear bug spray and haven’t been bothered by them, so I don’t think they’re much of a problem around us.

Salt marsh mosquitoes

I’m sure almost everyone has run to the car to get away from these vicious mosquitoes and their painful bites! Aedes taeniorhynchus and Aedes sollicitans are two common species found along the Texas coast. They lay their eggs in brackish and saltwater pools left over from the tides. There is no mystery about these ladies. They’re big, they’re hungry and they will come after you any time of the day whether you’re swatting at them or not. They are larger than many freshwater mosquitoes so they’re bites actually sting a bit. In other parts of the world, they are vectors of Venezuelan and Eastern Equine Encephalitis. Luckily, in our area, this is not a problem, but they are a prime vector of dog heartworm, so if you live near the beach, keep your dogs on a heartworm preventative.

I certainly had my fair share of them at the beach, which is what got me thinking about other parasites that may be lurking at some of our favorite vacation destinations. My conclusion: wear bug spray and heed any warnings at the beach and you should be in tip-top shape. You’ll hopefully leave with nothing worse than a minor sunburn and relatively few mosquito bites! Until next time, happy bug watching!

Erin M
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 Director of the Cockrell Butterfly Center. She is constantly striving to improve the butterfly center and how it serves and educates the public about the wonderful and amazing world of insects! As a Board Certified Entomologist, Erin has extensive knowledge of insect identification, ecology, plant relationships, husbandry, really any insect-related topic!

11 responses to “Beach Bugs!”

  1. Laura says:

    Talking about insects as vectors for diseases, sand flies are also. Of the top of my head I know that they can spread Leishmaniasis (or as I call it, melting face disease – it’s pretty horrible). They also apparently carry Chandipura virus (related to Rabies). So good to use insect repellent if you are going anywhere with them.

  2. Alaina says:

    Thank you for the great info! I’d love to share this on our site. Is it okay if we reblog? 😀
    Anyway, bugs have never kept me from the beach, but I really don’t enjoy mosquito bites.

  3. Cheyennne says:

    In your first section on sand lice, you stated that they were tiny crustaceans. Directly after that you stated that they are jellyfish larvae. Jellyfish are Cnidarians, Crustaceans are Arthropods. These are very different phyla. So just to avoid confusing the public further, sea louse are a type Crustacean, which is in the phylum Arthropoda. There are many different types, but they are all in the family Caligidae. As far as I can find, jellyfish larvae (whether you consider this the planula or ephyra stage) do not parasitize humans.

  4. Erin M. says:

    Hi Cheyenne,

    I certainly know that crustaceans are arthropods ( um, I study arthropods) and that jellyfish are cnidarians. I was not stating that they are all the same thing. I can see how you might misunderstand what I was saying there. What I was trying to explain was how common names that are generally accepted for certain animals can be given to others as well. So, while sea lice are actually the crustaceans, some people in certain regions also refer to the immature jellyfish as sea lice. I also never stated that any of the above parasitize humans. I’m not a professional writer, so I may not have worded that first section in the best way possible. Thanks for reading!

  5. Mary says:

    I loved this thanks for the info
    I feel so much better about my vacation now because I have been getting bites on my leg and I was wondering what they where from THANK YOU

  6. Kinglind@telus.net says:

    We have found abundant little bugs – beigy white with black eyes 1-2 dozen legs and a crispy shell that attach to you while swimming over sand and eel grass in very warm waters south of Tulum. They seem to dig in a bit and we need to brush them off when we come out of the water. Any idea?

  7. Larry Shultz says:

    A particularly obnoxious species of horsefly is the : https://en.wikipedia.org/wiki/Tabanus_nigrovittatus
    It is found in the Newburyport/Ipswich area and on Cape Cod, both in Massachusetts.

  8. deluxe_fox says:

    i want to know the thing that lives under the sand at my beach. I don’t always step on one but often enough to have learned there is some kind of THING that lives beneath the sand (usually above the high tide mark but not always!) and if you tread on it just right, and the soft part of your foot touches it, it STINGS you with something that is mildly painful for about twenty minutes, maybe half as painful as a bee sting – and then itches like crazy for weeks afterwards. Location – Two Rocks, Western Australia. (as if all the snakes weren’t enough!)

  9. Scott says:

    Trying to figure out what get the heck bit us up last night at Crystal Beach in Galveston we were laying in the sand at night around 11 o’clock had no problem but then all the sudden we started being bit by something have bites all over my back that look like mosquito bites or chigger bites it was so bad we had to leave can’t figure out what it was any idea

  10. Erin M. says:

    Hard to say! Most likely it was not chiggers, you don’t feel those biting you. The saltmarsh mosquitoes in Galveston are really bad and their bites sting! That would probably be my best guess!

  11. Ray Simpson says:

    The sea flea that every one talks about are called Sandy Loppers.I have seen millions of them.One of our local beaches near Berwick-upon-Tweed named the “Sandy Beds” One evening I climbed down onto this beach,the sand was alive with them they feed on dead sea weed that has been buried by Winter Storms also dead things that get washed up.They don’t attack humans. They are small shrimp like with two black eyes on the side of their heads and can swim very fast in water.

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