Lately, there's been a lot of controversy on whether or not to use pesticides in purple martin nests in order to control insect pests such as blowflies and nest mites.  This is one of the most controversial issues I've run across in this hobby and the following is where I stand on it.


First some background:


When I first started out with hosting martins, I ran into a number of problems and at the time, I really didn't know where to turn for help.  I knew of a few people that had martins, but when I asked them about what to do, I seemed to get a different answer from each one of them.  Some of these folks didn't even know about what goes on in a martins nest because they never did nest checks.  Just put the house up and let them be.  I quickly learned that even though I was new in the martin hobby and relatively inexperienced, I knew just as much as most of them.


Being the kind of person that wasn't satisfied with the kind of answers I got, I went searching.  I got hold of some books and of course, back then the internet was new, however I did find a few web sites.  The book authors seemed to know what they were talking about as well as the authors of the internet sites, but again the information I was looking for varied from author to author or was non-existent at all.  So, I kept digging, and little by little, my knowledge increased, and I was slowly beginning to understand this hobby a little better.


Well, many martin seasons have now come and gone and I still sit, marvel and wonder about these beautiful birds.  At my home site, I'm constantly making changes, doing testing and generally trying to see just what makes these birds tick.  What things do they like and dislike?  What works and what don't?  Compartment sizes, entrance hole sizes and shapes and even things like how high should the housing be and do they like or dislike a full nest of new material when they first arrive back each spring?.  I've run into all kinds of problems and through research data from other organizations and my own experience, I've managed to overcome most of them and have a fairly nice and lively colony to show for it.  The world of purple martins is changing and the way things used to be are also changing and it's our responsibility to educate ourselves and keep pace with it. 


However... there is one issue in the purple martin hobby that nobody has taken by the hand and run with yet and that's the use of pesticides (in particular, 5% Sevin®) in martin nests to control nest mites.  When I first ran into these little critters, I was totally baffled.  Nowhere could I find any good literature about what to do about them.  As best I could tell, at that time there were three main thoughts.  


One, leave things as they are and let nature take its course.  However, my own common sense tells me that's not a smart decision at all.  These young birds had nowhere to go to escape these biting little pests and were literally being eaten alive by them and if I'm going to keep martins, then I'm going to do something about the mites.


Two, do complete nest changes, removing the old nesting material, wiping down the nest cavity and replacing with a totally new nest.  But, no matter how hard I tried, it didn't get rid of all the mites and within a short time, the process had to be repeated again and if a lot of nests are had, that could get to be a very time consuming job.  I tried the nest changes, but the mites got everywhere.  On my hands, arms, on my clothes and even in my hair.  My wife wasn't about to let me in her house with these things crawling all over me.  Plus, there were the mites that were still on the baby birds and in the nests.  All they did was lay more eggs and more mites were the results.


And three, the use of a substance called Diatomaceous Earth or DE for short.  I tried the DE just the way everyone 'in the know' at that time said to use it and as best I could tell, nothing happened.  In the days following the treatment, I saw no appreciable change in the number of mites and in the mean time, the baby birds were being devoured and I knew that couldn't be a good feeling.  There just had to be a better way to treat these pests so that they were gotten rid of once and for all.  


So again, to satisfy my curiosity, I started my digging.  What other materials could be used to control mites?  I have enough common sense to know that some materials are caustic and could be immediately harmful to young birds and I didn't want to use any of those, especially anything that 'sprayed' from a can.  Spray 'anything' under pressure is not controllable.  However, I already knew that 5% Sevin® dust was a very mild pesticide and I looked into it.  We humans use this chemical on a daily basis in our gardens and then eat those foods within a couple of days and I know that if it were the least bit dangerous to humans, it would be all over the labeling.  I talked with a chemical engineer friend of mine and he gave me a good background on the substance and said that of all the chemicals available, this was the best for general use around the house without any major after effects.  In fact, the label even told how to use it on our pets.


Well, I took a small plastic spoon and tried just a little bit of it in the infected nests and, WOW!!!  Within 24 hours, no more mites  I couldn't believe what I witnessed and couldn't wait to tell others what I'd discovered.  So, it was off to share my findings with a few folks on a purple martin forum that I frequented at the time.  Again, WOW!!!  Talk about stirring up a hornets nest.  This was one subject that really brought out the differences in people.


This issue was brought up a few times on The Purple Martin Forum and every time, it became a very passionate debate between pro-Sevin® and anti-Sevin® forces.  So much so in fact that one day, a guy by the name of Kenny Kleinpeter from Baton Rouge, LA. and myself decided to take it upon ourselves and investigate deeper into this issue.  Someone had to investigate this issue and come up with some educated information that everyone could read and see what really happened with this stuff.  (The final results are added at the end of this article for anyone else that wants to read it for themselves so they too can make an informed decision.)  The issue became so hotly contested in fact, that the Purple Martin Conservation Association has decided (although nothing to date has been done about it) to do and in-depth study themselves on the use of Sevin® for mite control in wild birds nests and the long term effects thereof.


One thing I noticed in the course of my digging and debating was that people were one of three general attitudes.  The "no comment" attitude, the "anti-Sevin®" attitude or the "pro Sevin®" attitude.  All three have their stands and their reasons why they feel the way they do, but I for one wanted to know more, hence my decision to dig a whole lot deeper into the subject.


I found that the "no comment" individuals seemed to be either on the fence or didn't want to rock the boat.  They might have monetary interests or a public image to preserve and didn't want to be seen as 'controversial'.  However, not being one that worries about public image, I'm definitely not in this group.


I also found that many "opponents" to the use of pesticides would fall back on a couple of different thoughts.  One was a particular statement on the label on the package that states, "This product should not be used in any manner that is illegal or unsafe".  Well, no kidding... In fact, everything manufactured in the U.S. has a label that says that.  It's known as a 'cover thy butt' statement so that the product manufacturers don't get sued by everybody that tries to use their product for uses it wasn't intended.  That statement is for people that try to trim their hedge with a push lawnmower, cut their arms off and then sue the manufacturer because he didn't see a label that said not to trim hedges with his push mower...or the lady that pulls into a fast food drive-through, asks for a cup of 'hot' coffee and then drives away with it stuck between her legs, spills it and burns her legs beyond recognition and then sues because there wasn't a label on the cup that said "hot coffee is hazardous".  I'm one that believes we need to use a little 'common sense' in our daily lives, a trait that is surprisingly lacking in a lot of individuals.


The second thought the opponents usually throw out is that adding anything to a migratory birds nest is illegal.  So!  So is changing out the birds nest (which is what is advocated).  In fact, any kind of tampering with any kind of native birds' nest is illegal.  So, who's really breaking the law, Sevin® users or nest changers?


Although not always, many 'opponents' to using Sevin® look at it as, 'pesticides are poisons' and don't bother to go into any more depth on the subject to find out any information for themselves.  They have a general dislike for pesticides and let it run over into this issue.  They are usually known as 'anti-Sevin®'.  Again, although not always, many of these people haven't done any background work on the issue and are only repeating something that they heard from someone else.


An then there's the folks that 'use it' but don't come right out and say it.  (Closet landlords).  They know Sevin® works, the mites are gone, the birds seem healthy and that's all that matters to them.  They're just afraid that, if they speak out in public, they'll be pounded by all the anti-Sevin® forces about its use, so they just keep it to themselves.  Their nests are mite free and the young don't have to suffer in the nests from thousands of blood sucking mini-mouths that are sucking the life blood out of them because they are powerless to get away from it.


I'm the kind of person that likes to know as much about a subject as I can and in this case, I specifically wanted to know as much as possible, because I am dealing with a poison..  Yes, I do agree that  it's a poison, it kills insects and I wouldn't want to use anything on my birds that would harm them which is the reason I started digging for more information on it..  I dug and printed until I had mounds of paperwork in front of me and then I started reading.  (If you want to see for yourself what I ran into, just do an internet search on the word "Carbaryl" (the basis for Sevin®) and start reading).  I found all kinds of information on Carbaryl, (N-methylcarbamate).  Although I don't know exactly how Kenny did his, I'm fairly sure the same general procedure was followed.  I hi-lighted every thing that was either pro or con on the material, thus condensing it.  From that information I then sorted to fit my study, removing all the aquatic references, all the pet and vegetable references and kept the parts that referenced birds and then, once compiled, I studied it and made my conclusion.


One good thing about doing a search for myself, I found out a lot of things I didn't know before.  I found that Carbaryl was developed for the poultry industry to keep the chicken mites off of them and since I was interested in birds, I kept my study zeroed in on this direction.  Carbaryl is very toxic to aquatic invertebrates, but I'm not planning on using it near my pond.  It's very toxic to honeybees and other garden insects, but I'm not planning on using it near my honeybees, either.  Nowhere did I find anything that was detrimental to using this product on birds.  Everywhere I found disclaimer words like "may" and "possible" or "inconclusive results" or "inconclusive data".  I found nothing that claimed it was carcinogenic such as is seen on the DE bag.  If the label is read on the bag the Sevin® comes in, you'll find the typical precautionary statements having to do with humans and it even describes how to rub it on your pets, but nowhere does it say anything about birds.  In fact, in the study, very little information was found on its use for birds, even though it was formulated for chickens.


My conclusion from this investigation:  

5% Sevin®, (Carbaryl), is one of the mildest and most widely used pesticides on the market today.  It's used in our gardens for our fruits and vegetables and it's used on our pets for mite and flea control.  The methods for use are very controllable.  The quantities used can also be controlled very accurately.  The active ingredient, N-methylcarbamate, becomes inert after 3 days once exposed to humidity and light and thus becoming harmless.  (No, it does not stay in your martin houses all year long as some might think).  Plain old harmless Talcum powder is used as the substrate of which each bag contains 95%.  5% Sevin® was developed for use on birds with no or very low side affects indicated.  And although it is a poison, it is the least dangerous to us humans.  In fact, as far as poisons go, it is the least dangerous to use, period.


Now, is all of this grounds to consider Sevin® (Carbaryl) harmless in bird nests, probably not.  But at least I educated myself on the subject enough to at least know what I was talking about rather than listening to someone who didn't and was simply stating that it's a poison and "poisons are poisons" and therefore shouldn't be used period.  And I'm not one to jump on someone else's band wagon just to fit in.  I want to educate myself and then make my own decisions from the knowledge that I gain.  In fact, to gain even more knowledge about the subject, I'm doing testing in my own colony to see just how much it can be cut, (using pure talcum powder to do the cutting) to see just how little can be used and still be effective.  The Purple Martin Conservation Association is aware of my testing and I'm keeping them informed of my progress.


At present my treatment 'on infected nests only' consists of using 'less' than a level 'teaspoon' of 5% Sevin® spread on the nesting materials just inside the entrance hole of my martin nests, then tap the material so that it settles down into the material and, within 24 hours, I have "no" mite problems at all in them.  It doesn't have to be over-done to kill them and 'one' treatment per year is all that is required.  Am I telling you to use it?  NO.  If you want to do nest replacements to treat your mites, then fine, have at it.  But I have a fairly good sized colony and just don't have the time to change out all the nests that I have.


In this modern day and time, I am not so naive to think that we can get along without chemical poisons.  In fact, it's just the opposite.  Every single fruit and vegetable we buy from the market today has chemicals used on them to get them to market in the shape they are seen.  Anybody that doesn't think that statement is true is living in his or her own little world and needs to get out more.  They should follow a farmer around some day.  And, the chemicals that the farmer is using on that fruit is many times worse than 5% Sevin® dust.  


My Tests with 5% Sevin®:

If anyone wants to see the results of a 2 year test that I did myself, take a look here. My Sevin Testing


Oh, and for anyone that believes that Diatomaceous Earth (DE) works in the control of nest mites in martin houses, you're only kidding yourself.  Stop to think about it for a minute.  It's abrasive and supposedly works by cutting the exoskeletons of insects.  If that's so, imagine what it does to the lungs of baby birds that have to breathe it all day because they're practice flying in their compartments and dust is flying everwyere.  Plus, the label on the package says that it "may" be a carcinogen and that means, cancer causing.  So really, who's doing the most harm?



Sevin® Investigation:


The following are the results of the investigations that Kenny Kleinpeter and myself did on the 5% Sevin® issue and they are here for everyone to read and educate themselves.  Again, I'm not telling anyone to use Sevin®.  That's your decision.  But at least take the time to educate yourself about it before making any kind of decisions.



INTRO:  The Great Sevin® Debate


Well, folks, here it is -- pro and con -- all laid out. This is not a scientific study. It's the work of two (somewhat) normal guys searching for truth and trying to make informed decisions. Factors like common sense, instinct, risk and prayer entered into what we present to you. Please, take it for what it is, two opinions. I would guess that most of us, intellectually would fall somewhere in the middle ground and have to move, emotionally to one side or the other.


All of our data will be turned over to Louise at PMCA. It is our hope that it will be helpful to them as they study the problem more scientifically and reach a decision that we will follow and further the cause of a troubled species, the Purple Martin.


Thank all of you, too numerous to mention, for your knowledge, passion, debate and civility. Pro or con, we all have the best interest of these birds at heart.


-Chuck Abare and Kenny K


Kenny Kleinpeter




It is an awesome responsibility to lure a wild creature into our midst and try to provide for it. While I've heard otherwise, knowledgeable people have told me that martineering is "no big deal, all you have to do is put up a house", I know that there's a lot more to it. While we may claim to know when "our" birds are happy or sad and apply other "human" characteristics, they are complicated creatures that have very different sets of problems and solutions. Problems such as temperature, predators, nesting competitors and, the most insidious, parasites serve to make their lives miserable. We can do much for them. We can design or modify housing to make them cooler in the summer and warmer in the winter. We can build guards against predators and traps for competitors. We can also protect them against parasites; in fact, we can do too much for them in this area.


It's bad enough that 90% of birdhouse owners do nothing management-wise to help their birds. They are lucky if they are producing enough martins to prevent population decline. It behooves the remaining 10% of us to work efficiently and intelligently to produce absolutely all of the birds possible within the constraints of our individual designs and capabilities. Controlling parasites mechanically (nest replacement) and naturally (judicious use of DE) is all I've ever had to do. Granted, different areas deal with different pests, but the landlord should start without chemicals. Indeed, with reasonable checks and practices of nest replacement, chemicals may never be necessary.




The federal law that governs pesticides is called FIFRA -- the Federal Insecticide, Fungicide and Rodenticide Act -- passed in 1947 to regulate "economic poisons". The U.S. Department of Agriculture (USDA) administered FIFRA from 1947 to 1972. While the USDA handled the pesticide industry, no testing was required. In 1962, Rachel Carson's book, Silent Spring, exposed the irresponsibility of the USDA and documented the destruction that pesticides were causing. In 1970, the Environmental Protection Agency (EPA) was created. In 1972, FIFRA was amended to require testing before pesticides could be registered and marketed. Pesticides already registered by the lax USDA were to re-register by 1975. The pesticide industry has managed to extend that deadline to beyond the year 2000! The EPA has also allowed pesticides to be sold with "conditional registration." 1


It is obvious to me that the chemical industry has control over the politics of protecting our environment. Just because a chemical is sold does not mean that it is safe -- this goes for humans as well as purple martins.




The EPA's success is based entirely on its labeling laws. Companies spend millions of dollars and several years testing products 142 different ways according to EPA guidelines.2 When EPA approval is given to market a product, strict directions for usage, determined from those tests, are stated on the label. Everything an end user needs to use a registered pesticide properly and safely is on that label. That label is a legal document that we are obligated by law to follow. The first thing you read under DIRECTIONS FOR USE is this statement: "It is a violation of Federal law to use this product in a manner inconsistent with its labeling. READ ENTIRE LABEL. USE IN ACCORDANCE WITH LABEL PRECAUTIONARY STATEMENTS AND DIRECTIONS." Strong words. Just what does that mean? It means that it is illegal to deviate from the label to any degree in using the product. Only specific uses listed on the label are allowed. Penalties include Civil ($500 for first offense, $1000 for subsequent offenses) and Criminal (misdemeanor, fined $1000 and/or imprisoned for 30 days).3


The majority of us are law-abiding citizens who place faith and trust in our governments to make intelligent decisions regarding our lives. I estimate that 20% of us lack that faith and trust to some degree. In these cases, it is important that we intelligently understand what's at stake when we circumvent the law and apply these chemicals as we see fit.



Carbaryl (Sevin ™) is said by the EPA to be "one of the most widely applied insecticides in the US," since use began in 1959, with 10-15 million pounds used annually. There are two reasons for its popularity: low oral and dermal toxicity for mammals and its broad spectrum of insect control. Carbaryl breaks down readily into less toxic byproducts. It has low toxicity to birds and no precautionary language for birds or fish is required by the EPA. It has extremely high toxicity to honeybees, aquatic invertebrates and certain estuarine organisms. It is moderately toxic to fish. The EPA has approved carbaryl for use against insects on several fruit and vegetable crops, plants and trees. It is also approved for use on poultry and pets and indoor use.4


It is evident that carbaryl is a relatively safe pesticide. That is, it is safe for humans. The fact of the matter is that sufficient testing has not been done in order for the EPA to approve it for use with birds other than poultry. Purple Martins are not poultry. Poultry are defined as domesticated birds.




Environmental contamination by pesticides gained attention in 1962 with Rachel Carson's book, Silent Spring. Finally, after public outcry, pesticides like DDT began to be banned. Besides being very strong, more dangerous is their persistence - staying chemically active for long periods of time. An amazing fact is that the United States produces more DDT today than it ever has. It is exported to countries like those in Latin America where migratory birds winter. Actually, we consume the imported produce that these banned pesticides are used to produce! Overall, the world produces over 5 billion pounds of pesticides annually. Where does it all go? In short -- nowhere.


It is estimated that 67 million birds are directly killed from pesticide poisoning every year. This is a very conservative estimate as most deaths go undetected. Diazinon was the first insecticide specifically restricted because of thousands of bird deaths. It was used to kill insects on lawns and golf courses. Millions of pounds are still used in the United States every year. About 40 active ingredients in pesticides have been found to be lethal to birds. About 25% have been banned (only in the U.S.). Most birds are exposed by ingestion, such as mistaking a pesticide granule for a seed or by consuming contaminated prey. Pesticides can be absorbed through the skin or breathed when flying through aerial applications. Sub-lethal effects include: eggshell thinning, deformed embryos, slower growth rates, decreased parental attentiveness, reduced territorial defense, lack of appetite and weight loss, lethargic behavior, suppressed immune system response, greater vulnerability to predation, interference with body temperature regulation, disruption of normal hormonal functioning, and inability to orient in the proper direction for migration. Each of these sub-lethal effects can ultimately reduce populations as effectively as immediate death. Pesticides can also affect birds indirectly by either reducing the amount of available food or altering habitat.


Purple Martins and other Neotropical migratory birds are potentially exposed to more pesticides than resident birds. While we have, at least started to clean up our environment, Latin American countries have not. Pesticide contamination is often cited as one of the factors in declining numbers of migratory birds but there is little evidence to support this claim. It is difficult to determine the role of pesticides in causing death or reproductive failure. It has been shown that acephate, an organophosphate, can interfere with an adult bird's ability to orient itself in the proper direction for migration. Who knows how many vagrants are sighted for this reason? When fat reserves are used up, like during migration, pesticides are liberated within the body to cause death. No one knows how many die during this time. We accept the fact that only half of young birds survive to return each year. Who can say what part pesticide poisoning plays in this fact?5


Until priorities can afford to be shifted from protecting (but still being able to feed) humans to protecting all animals, we must educate ourselves to the possible dangers of pesticides and practicing alternative pest control methods. Buy organically grown products and support organizations that work to reduce our dependence of pesticides.




I have had tremendous success using diatomaceous earth (DE) and practicing nest replacement. While locations and different weather produce different pests, I think it important to start with a natural, chemical-free method and gradually incorporate stronger methods that are supported by federal and local authorities and do not violate the law. Your county extension service are excellent starting places.


I apply DE once before nesting begins and again after egg laying. I replace nests with cedar chips after the hatchlings are 10-15 days old. I have seen very few mites in any of the other houses I treat. Of two houses that I monitored but did not replace nests, one had a mite infestation. ____________________


NOTE:  Sorry but the links that originally accompanied this article no longer work so they have been removed.





Chuck Abare




Purple Martins are very adaptable creatures. If they hadn't been able to make the shift from nesting in trees to human prepared nest sites, they would not be nearly as numerous. Because we have attracted them, we have a responsibility to provide the best care that we can for them. We build housing that protects them from outside factors like weather, predators and nest competitors. We even supply calcium-rich eggshells or grit to supplement their diet. One area that is under debate is the prevention of pest infestation. Mites, lice, ants and blowflies can make the birds miserable at best and even manage to kill hatchlings. By having the birds in such close proximity to each other causes the pest problem to explode. In effect, we have caused the problem, so we must solve it. Nothing is nearly as effective as 5% Sevin™ Dust. Careful dusting at the onset of pest infestation effectively eliminates them. A one-time application solves the problem for the breeding season. Data from the EPA clearly shows that this pesticide is safe. Certainly, the risk of chick mortality is greater from pests than from Sevin™. Research needs to be done to find the most efficient (minimum) dosage and application techniques so that we minimize the risks to the birds.




Landlords who use pesticides are concerned as to the legalities of their usage. Technically, it is illegal to use diatomaceous earth (DE) or anything else for that matter on a wild bird nest. Realistically, prosecution would not be likely as we are aiding the birds by our actions. The key is making sure that the smallest amount necessary is used in order to minimize the risk.



The EPA's own data from their Integrated Risk Information System (IRIS) shows just how safe Carbaryl (Sevin™) really is. In order for Carbaryl to even affect a human, 5.48 mg/day. It has a moderate to low mammalian toxicity. It is not considered to be an oncegen (tending to cause tumors). It is a weak mutagen (tending to cause mutations) and available data indicates that it has only low teratogenic potential (causes extreme malformations or monstrosities). Carbaryl is not expected to contaminate groundwater. While it is extremely toxic to aquatic invertebrates and honeybees, it has only low toxicity to birds. An important aspect of Carbaryl is how quickly it breaks down and is rendered harmless. Its insecticidal properties are lost after 3-10 days. Most animals, including humans, readily break down carbaryl and rapidly excrete 75% of it in 24 hours. Data suggests that there is low to very low toxicity to birds.1




Most landlords are using a teaspoon of 5% Sevin™ Dust applied under the nest at the first sign of nest mites. It would be worthwhile to try using a 2% dust in some gourds to see if a smaller dosage would be sufficient. Also, when to dust or spray may be important. Wet solutions have been applied to cavities before nesting will success. Could dusting also be done that early? These are questions that need to be answered.




The presence of pests on Purple Martins and in their nests is a serious health risk. A quick and serious solution must be found for these birds that need our help to survive. A 5% Sevin™ Dust seems to be a most effective and low risk method to solve the problem. Just as laws make it technically illegal to make nest replacements, return fall out hatchlings to their nests and, even to use DE, a sense of reason and common sense should allow us to properly care for this exceptional bird. As long as a minimum dose is effectively applied, it surely is in the best interest of the Purple Martin.


1. Sevin: A Controversial Insecticide by Winand K. Hock


This Page Created and Maintained by Chuck Abare