Do eggshells in compost attract rats?

QUESTION: Do eggshells in compost attract rats? Should I put them in the disposal or throw them away, or can I compost them? Mark M

ANSWER: It usually isn’t a great idea to put eggshells into your compost, as they take a very long time to decompose. More importantly, eggshells do attract rats. Eggshells, especially if they are not rinsed, have egg residue on them, which dries and can smell. The smell of eggs is a sure fire way to invite rats to your compost bin as if you were throwing a party specifically for rodents to attend. 

Aside from eggshells, avoid adding any cooked meat or fish products, or anything that is particularly strong-smelling like cheese and fats to your compost bin. Eggshells seem to be a personal favorite for rodents though, so be sure to keep them out of your compost, and if you’re going to use them in the garden for any reason, such as to deter slugs and snails, be sure to wash them well first, removing any trace of egg residue. 

Other than strong smells, rats may be attracted to your compost bin for several reasons. Because you use your composting system to discard kitchen scraps, it provides a food source. Properly functioning compost piles are also a good heat source. If it’s cold outside in your area, rats may be attracted to your compost pile because of its warmth Compost bins are usually kept in dark, tucked away locations, just the type of spots where rats are known to dwell.  

Luckily, there are a few simple preventative tactics that you can implore to rat-proof your compost bin and keep rats away from your compost, and your garden area in general, aside from throwing your eggshells in the trash instead of the compost. First, use a solid-sided container as your compost bin. If you are using a wooden, open-slatted bin for composting, only use it for garden waste and keep your kitchen scraps and vegetable peelings in a closed bin with solid sides and a well-fitting lid. 

Most plastic commercial compost bins are made to be rat-proof, with a thick rat-proof base. However, if yours doesn’t have a rat-proof bottom, place it on wire mesh. Rats can surprisingly squeeze through gaps that are just over half an inch (or 15 mm), so the holes in your wire mesh need to be smaller than that, and made out of a heavy-duty material. Rats have super sharp teeth and can gnaw right through chicken wire in no time. Use a galvanized light welded wire mesh that is at least a half an inch by a half an inch thick so that rodents can’t chew right through it. 

Set the bin up squarely to ensure that there is no gap between the sides and the lid to make it harder for a rat to chew a new entryway into your bin. If they can find an edge to chew on, they will eat through the plastic until they have made themselves an easy entry/exit hole in your compost bin. Rats don’t like to be out in the open, but rather prefer to stick to the sides and edges where they have some security and a protected passage to scurry across. So, if possible, place your compost bin or pile right out in the open, as far away from fences, sheds, and structures as possible to discourage them by giving them no place to hide near your compost. 

Rats also hate loud noises and surprises. So place your compost bin in a location that you pass by regularly and use a stick to whack the side of the bin loudly every time you pass it by. This will make them think twice about setting up home base in your compost heap. Survey your garden to locate places where rodents can easily hide, such as tall grass, or wildflower meadows. While ornamental grasses and wildflowers may look nice in your garden, they can be a hotbed for rodents too. Make sure your compost bin is far away from any places where rats can easily hide in the grass. 

Birds are messy eaters and can easily leave enough seed on the ground to keep a few rodents well fed. If you have a birdfeeder, consider placing a slab of pavement or some sort of flat surface beneath it so that you can easily sweep up fallen seeds that your neighborhood birds leave behind. You may prefer that the rats eat spilt seeds to feast on your garden’s goods, but the ultimate goal is to drive the rats off your property completely, so leave no stone unturned when rat-proofing your property. 

If you carry out several of these rat-proofing measures and are still having troubles with rats, you may have no choice but to invest in a heavy-duty tumbler composting system, or even to hire a pest control company to come out and lay out traps or poison. However, in most cases, just a few rat-proofing tactics will send them in search of a more comfortable habitat. Once you have taken all the necessary steps to rat-proof your garden, compost bins, and property, with any luck, the rats in your area will most likely move on to less hostile environments.