a live trap. Catch the cats and then do whatever you want to with them. Possibly they might have tags on them that you could trace back to an owner, or take them to an animal shelter where the owners would have to pay at least to get them back and maybe they'd think twice about turning them out again....

Go to Sam's or some other wholesale store and buy a very large quantity of cayenne pepper. Sprinkle it around the greenhouses. The cats get it on their paws which burns and when they lick their burning paws it burns their mouth. More importantly, call the local police or sheriff, show them the damage and file a complaint. Then capture the cats. The cat owners may be liable for the damage. If they aren't liable, you may be able to turn it in on your insurance. There may be a leash law in your area which may require the cat owners to keep the cats confined or on a leash. While you may not receive any compensation from the cat owners, you can file a complaint, have the police issue a citation and you can go to court to ask the judge to fine the owners for the max. Use the complaint you filed as evidence of damage caused by the cats. Take videos of the cats at their worst if possible.

Here we go again...

Catch the cats, kill the cats, sue the owners of the cats.

Guess what? You have not solved the problem!

There will be more cats, the cycle repeats.

One day someone will realize not to erect a poly covered greenhouse in a place where there are cats.

Just like someone wil realize it is a waste of time growing sweet corn or tomatoes in a place infested with raccoons! (um... me.)

One day we will not build cities that are below sea level...

Now to get really serious.

mobjack68 you say "It seems that the local cats have started to climb on the houses." what triggered this?

Is the covering new?

I have first hand experience of this very problem and NO cats were killed.

I guess the cats may be being drawn to the warmth.
Having claw holes everywhere will certainly increase your heat losses and perhaps the cat problem with it as you dont have "still air" in the cavity anymore.

Maybe a sprayer system fixed at cat height around the base of the greenhouse (facing out) with PIR sensors to trigger it would deter them before they got close enough to climb the poly?

Cats will climb anything to get to something they want, especially if they are excited. They could be chasing bugs, lizards, or anything else that catches their eye. And as someone else mentioned, they could be seeking out a place to laze in the sun. I don't know how they can handle it myself but it could be 100 degrees outside and they will still seek a place in the sun to bask.

I've trained dozens of cats in my lifetime and if one thing will work (without killing them) it is a surprise stream of water out of nowhere. They learn quickly and rarely return to whatever bad habit you are trying to break because they develop that Pavlov reflex. It may take a few times but they get the point eventually and learn to associate the house with bad karma. On the other hand, I am not sure how expensive that would be unless you kept a watchful eye and stayed armed with a spray bottle with a nice strong stream vs. an automated system. A super soaker outside would probably be more fun though! They do some neat tricks in the process of trying to get away too.

For what it is worth, you could always put up what is called a cat fence around the greenhouses. It basically utilizes PVC pipe in a manner where when they try to climb the fence it rolls and they can not get a foot hold to climb over.

There are passive controls of populations as well. There are some organizations that will neuter/spay them for free if they are feral. And they put them to sleep if they have communicable terminal diseases. It would be a time investment but no killing, no babies, very little money (I think the going rate is $10 per cat IF they charge you at all), and fat fixed cats are less likely to be ambitious enough to wander too far from where their colony is. The organization here is called friends of feral felines.

a layer of chicken wire laid over the top should do the trick. They will not be able to walk easily on it and will find it unpleasant, I think. Also see if you can figure out the attraction and eliminate that.
But do be sure it is cats (by that I mean, you have seen them). In my neighborhood I have heard cats blamed for damages caused by racoons, possums, squirrels, and even woodpeckers!

if they are feral, dispatch them with whatever means necessary. A.22 works well and you can get loads that are quite. Feral cats destroy natural populations of wildlife. They have no place in the ecosystem.

If they are housecats, try sprayer or sprinklers attached to motion sensors. They work good on deer, not sure if a cat is large enough to trip the sensor.

A motion sensing water canon will work on cats but if it is really raccoons they'll enjoy it.....

Here is a link that might be useful: DIY water canon

Cats will climb anything to get to something they want, especially if they are excited. They could be chasing bugs, lizards, or anything else that catches their eye. And as someone else mentioned, they could be seeking out a place to laze in the sun. I don't know how they can handle it myself but it could be 100 degrees outside and they will still seek a place in the sun to bask.

I've trained dozens of cats in my lifetime and if one thing will work (without killing them) it is a surprise stream of water out of nowhere. They learn quickly and rarely return to whatever bad habit you are trying to break because they develop that Pavlov reflex. It may take a few times but they get the point eventually and learn to associate the house with bad karma. On the other hand, I am not sure how expensive that would be unless you kept a watchful eye and stayed armed with a spray bottle with a nice strong stream vs. an automated system. A super soaker outside would probably be more fun though! They do some neat tricks in the process of trying to get away too.

For what it is worth, you could always put up what is called a cat fence around the greenhouses. It basically utilizes PVC pipe in a manner where when they try to climb the fence it rolls and they can not get a foot hold to climb over.

There are passive controls of populations as well. There are some organizations that will neuter/spay them for free if they are feral. And they put them to sleep if they have communicable terminal diseases. It would be a time investment but no killing, no babies, very little money (I think the going rate is $10 per cat IF they charge you at all), and fat fixed cats are less likely to be ambitious enough to wander too far from where their colony is. The organization here is called friends of feral felines.

That's an interesting feature in the forum software. Hit the back button a few times and my message reposted....

I apologize for that.

trapping cats is easy. Havahart traps work well. Put the trap up on an elevated platform to keep skunks out. You can drop them off at the nearest shelter or schezuan resturant (they taste like chicken), or you can take up tanning and the cat IS the hat... take that Dr. Seuss!

Do not release them as they will return and you will never trap them again. If you must let them go, the center strip of a busy 4 lane highway is a good place. Many animals seem to like it and find it very peacful. I often see them sleeping on the side of the road where they can get the warmth from the tar. I think the singing of the tires lulls them to sleep.

I've not had to use poly tape, would that work rather than replacing the entire covering, or is this an aesthetics thing being a business?

How about a couple of strips of duct tape, sticky side out?
or VELCRO!! It'll be tough pulling all those cats free from the side walls though. Wear gloves!

A strip of Cat strength Tanglefoot? Cat strips?

Do you have a bunch of hose that you can connect to a vacuum? I saw it on Tom and Jerry once where the cats all got sucked up into the vacuum bag. It's a hoot watching all those cat-shaped lumps work their way down the hose...

I'd think you already have sprinklers you can set up. Should be easy enough to use a motion detector to trigger them. Just be sure to shut if off before the cusomers arrive.

If there's a falconry club nearby they might appreciate a place to train...

Obviously this is a big problem for you. Is it typical though? I am putting up a GH in a field where the neighborhood cats frequent. Am i doomed? Should i start clearing them out now? I have trapped them before and taken them to the animal "Shelter" next town over, never to be seen again, but there always seem to be new ones to take their places. I may need to get a couple of traps now. *sigh*

Poppa

I hope mobjack has a kinder hear then some of the posters here do. Cats, feral or not will always be here, and it is because of HUMANS that there is such a problem, not the cats. They are doing what is instinctual to them, and to harm them because of it is cruel. I've had to learn to garden around the creatures, voles, raccoons, squirrels and feral cats; after awhile you learn what will grow and what won't. Then the 4 legged fur balls become a beautiful part of your garden instead of a destructive part. It takes a little work but in the end it's well worth it. There is some good advice here mob on how to take care of your problem without harming the cats; I hope you follow it.

Feral cats might be doing what is instinctual, too bad their instincts are too kill. What is cruel is the destruction these introduced predators do to the native inhabitants. Feral cats do wipe out populations of native inhabitants already on edge from loss of habit and pollution. Feral cats taken to shelters will be put down, every time. Feral cats are a huge environmental strain. Kill them!

Whatever you do with the cats you trap, turn up the pressure on the inflation fan a little bit as you get more holes. I have a friend with several large greenhouses and his own cats climb all over the greenhouses and he just turns up the pressure a little bit and it stays inflated just fine.
I hope my cat doesn't start doing this. My old one never did. It hasn't made the plastic give out in the wind or anything like that at his place, just a little more work on the inflation fans....

Kendal... There's an accidentally imported Asian beetle that's killing hardwood trees in New England and is spreading. The potential damage is staggering. The current solution is to cut down any infected tree and throw it through a wood chipper. Are you advocating that it's not the beetle's fault and that they are just following their instincts, hence we should leave them alone and learn to live around them? Grow things that they won't damage?

I suppose dogs that attack children are just following their instincts?

You're going to need a better argument than that.

Cats iz just cats. They are a tremendous drain on the natural wildlife. My daughter allowed a feral cat into her barn to control chipmonks. The day the Robin's nest disappeared and i saw the cat trotting to the barn with a nestling in it's mouth was the day it went to the "shelter". I trap any cat that's on my property. It goes to the "shelter" regardless of whether it has a collar or not. I have lots of nesting birds on my property. Cruel? *Shrug* I consider it cruel for cat owners to let their animals roam about destroying wildlife, spreading disease. The lesser of two evils i say.

BTW, i am a cat owner of a beautiful rescued animal kept IN THE HOUSE.

Poppa

.22 for cat. .357 for cat owner.

My cats live in the house.

Pot -> Kettle -> Stainless Steel

How do ecologically unfriendly species get introduced into habitats that are not natural to them? There isn't an issue stated here that does not relate back to the lack of forethought of the human species. Invasive species are carried around on our backs like little diseases and "bad" pets are the products of their ignorant owners.

While I agree that population control efforts are in order for invasive species, it seems to me that picking them off one by one is like putting an ace bandage on a compound fracture. Sure it may help a little in the interim but there is still a larger problem looming in the not so distant future and the potential for further damage is always there. The most effective effort is the one that gets to the very root of the problem.

Having said that, not everyone has time to go on a personal crusade and at that point it comes down to managing ones own corner of the planet. How a person does that is their business but in all fairness there is more than one way to effectively accomplish the task. Euthanasia is just the quickest and least expensive option to deal with the problem momentarily.

Did you ever find a solution? We have 4 greenhouses at our farm and the new mouse killers have started climbing on them. My husband is about to get rid of our cats but we also have a mouse issue and 3 kids who will be devastated. Any helpful info would be appreciated.

If you have power in them, why not try an electric fence as used for livestock, but made for pets.http://www.zarebasystems.com/store/electric-fence-accessories/kits