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How to protect yourself from Screwworms

Screwworm_larvaFlesh-eating maggots – say what?

I booked our tickets for the first scouting trip to Panama.  I’m so excited!  I have been doing research into Panama for several weeks now and the more I learn, the better it sounds.  This could be a real option for us for retirement. 

It sounds awesome: bio diverse, modern, beaches AND mountains, large expat communities, US dollar currency – how could it be wrong for us?  I posted on our Facebook page asking for tips from others that have been there and got a few good ones and then….. “we know people  that went there and you have to be very careful because of these big flies” and a link to a Wikipedia page about the nasty critters (aka screwworms) shown in the picture above.  And this is from my mother!

Ohhhh, man... Well, that just burst my bubble.  I read the wiki and sure enough it included Panama.  So, I proceeded to do a little bit more research into these little nasties.  Found some recent scary news about the Screwworms in the Huffington Post article on Rochelle Harris, British Woman, Has Flesh-Eating Worms Removed From Her Ear

OK, so these things are real, now what?

Here is how to protect yourself from Screwworms while you’re traveling:

(1) Get the facts straight

Although it is true the New World screwworm is a flesh-eating fly larva that can affect humans, it was eradicated in the US in the late 50’s and in most of Central America since the late 90’s.  Panama has been considered screwworm “free” since 2001. Check out the map in Figure 3 of this Food and Agriculture Organization of the United Nations’ report for Central America eradication dates.

Now, here is the catch:  eradicated does not necessarily mean completely gone. Screwworms can be spread back from other areas.  In fact, it is still occasionally found in the US. There was a new outbreak of the screwworms in the livestock in Panama in 2006 and 2012 due to a problem with the eradication methods, but it was in its southern region neighboring Colombia. Colombia has not yet eradicated these little buggers.

"Overall, these problems seem to be similar to the ones that occurred in Panama or
Chiapas, Mexico in 2003, a temporary increase due to a glitch in the eradication
program. In the case of Chiapas, Mexico, we know there was a breakdown in the 
sterile fly technology, so that the flies were no longer firing blanks but in fact
were breeding. After some technical adjustments, the program got back on track 
quickly, which is what I suspect will happen here. If the pressure is kept on the 
disease by movement control and effective release of sterile flies, this outbreak 
should be contained."                                        from www.aribvet.net

Some parts of South America and Caribbean also still have screwworms.  So, although not common, the screwworms can be a problem if you travel to tropical places.

(2) Know what it looks likefly

The fly that is.  It is bigger than a horse fly, has red eyes and is blue-green in color. Here are a few more pictures of the screwworm fly from Bing images.  If you see them flying around, take extra care to follow these precautions.

(3) Protect open wounds

The fly lays eggs in open wounds or soft tissue.  The larvae hatch and burrow into the affected area.  So, if you have a cut or wound of any type, be sure to keep it clean and protectively covered.  The area does not have to be large, it can be as small as a tick bite, so be sure you check for those as well.

(4) Pest Repellents

This is a good way to protect yourself.  There are several types of fly repellents on the market.  Why not take one with you?  My personal favorite one is this
No Pest Strip Unscented Hanging Vapor Insect Repellent. You may also try a bug zapper such as this one: Flowtron Electronic Insect Killer. They are compact and work well.

(5) Mosquito netting

When you are sleeping, it is best to sleep under mosquito netting or rooms with screen windows and doors.  There are other things that can be done but if you’re just visiting these are your best options.  Self-closing doors are recommended, so that flies don’t have extra time to get in.

(6) Clean Environment

What do flies like? nastiness and filth. They swarm around their own food source.  So, cover all food and store in refrigerator whenever possible.  Keep meats properly stored without exposure to air.  Don’t let trash sit around.

(7) Electric fans

Electric fans are really handy for creating air curtains across the door and window openings.  Think about it, the flies can’t fly against the wind.

(8) Animals

If you have pets, particularly dogs and cats that go outside, check them often.  They are at much higher risk of getting infested than you are. If you remove the screwworm from an infested animal, be sure to wear gloves. I will spare you the details of how to do this but if you’re not squeamish, google it and see for yourself.


So, moral of the story:  don’t just believe the hype and don’t be afraid to go outside.  If everything you read were true and happened everywhere, the locals would never leave home.

Be smart about your travels – these are useful tips no matter where you’re going.  You are unlikely to have screwworm problems.

They are nasty – yes; life-threatening – no.  And isn’t the one in this picture downright cute?


Happy travels.

You may also like our posts on Safety in Mexico and Safety in Costa Rica

All original photo credit in this post to ARS-USDA



About Joanna

is a Polish American living in Arizona with her husband Tim. She is a founding partner of JTR Tech and she is proud to be a professional geek. She had dreamt of living abroad for many years. So, she and Tim created AbroadDreams.com to document the process of making their dream of moving abroad come true. They spent 2 years in Puerto Rico and several months in Spain and Poland. Now they are exploring the American Southwest.

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  1. When we lived in Malawi, Africa, we had to iron waistbands if we hung anything outside to prevent nice little screwworms in our bodies. The flies laid eggs in the clothing. Other option was to dry all your clothes in the dryer.