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Entomology (Study of Bugs)/bites from being in lake water


Hi, I hope someone can help.  We have a holiday home on the edge of a water-skiing lake in England.  Our children are constantly in and out of the water and 2 weeks ago started getting covered in what looks like mosquito bites (over 80 bites on each child)

We have been advised the owners of the lake that it may be something called swimmers itch.  

There is a lot of weed in the lake and in some areas it looks really dirty, can larve cause a bite?  Is there anything that the lake can be treated with to help this stop happening again?

Dear Adele - This indeed sounds like a classic case of 'swimmers itch', caused by the larval stage (cercaria) of a parasitic worm that infects birds, especially waterfowl. These cercariae die very soon after penetrating human skin, and this appears to be what triggers an allergic reaction that results in the itchy papules on a victim's skin. Fortunately, there does not appear to be any lasting effect. Risk of swimmers itch appears to be greatest in shallow waters on hot, sunny days, and there is no effective control, but it does not appear to be all that common in Britain. See and for more detailed information.

Hope this helps,

p.s. - When my wife (a native of Dorset) and I visit England, we stick to the seacoast for our water exposure!

Entomology (Study of Bugs)

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Ed Saugstad


Will accept most questions in general entomology, including those related to medical entomology, taxonomy, ecology, arthropod surveillance, and pest management. If you are requesting a 'mystery bug' identification, PLEASE either attach an image to your question, or post an image on a web page (such as Flickr) so that I can look at it, as verbal descriptions frequently are insufficient for a definitive identification.


21 years in the U.S. Army as a medical entomologist; duties varied from surveillance of pest populations (including mosquitoes, cockroaches, ticks, and stored products pests) to conducting research on mosquito-virus ecological relationships and mosquito faunal studies. Ten years as a civilian analyst for the Department of Defense, primarily on distribution of vector-borne diseases worldwide. Limited experience on surveillance of agricultural insects in North Dakota and Indiana.

Entomological Society of America, West Virginia Entomological Society, Society for Vector Ecology, National Speleological Society, West Virginia Association for Cave Studies.

American Journal of Public Health, Contributions of the American Entomological Institute, Japanese Journal of Sanitary Zoology, Journal of Economic Entomology, Mosquito News, and Mosquito Systematics.

B.S. in entomology from North Dakota State University in 1963, M.S. in entomology from Purdue University in 1967.

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