How to Keep Mice & Rats Out of Stored Hay (Without Losing the Strings)

By the XES Netting team — bale net-wrap manufacturer · Updated July 29, 2026 · ~8 min read

Every hay producer knows the sinking feeling: you go to move your best second- or third-cutting bales in late winter and the strings are chewed through. Grab a broken one with the grapple and it falls apart in the air. As one HayTalk member put it, "the better the hay, the more they burrow in and chew the strings" (HayTalk: Mice Chewing the Bale Strings).

Chewed strings are the visible damage. The bigger problems are hidden: contamination and disease. Here's a practical, layered plan to keep rodents out of stored hay — the stuff that actually works, minus the folklore that doesn't.

Why it's worth the effort (it's not just chewed strings)

Rodents in stored hay cost you three ways:

• Structural loss. Chewed twine or net lets bales slump and fall apart during handling, and burrowing tunnels ruin the densest, highest-value flakes first.
• Contamination. Mice and rats foul feed with droppings and urine as they travel and nest. That's a palatability problem — livestock refuse fouled hay — and a health one. Rodents can carry hantavirus, leptospirosis, and salmonella, spread through their droppings, urine, and chewing, according to university extension rodent-control guidance.
• Wildlife that follows the rodents. A rodent buffet draws bigger visitors. For horse owners the serious one is the opossum, the definitive host of Sarcocystis neurona — the parasite behind Equine Protozoal Myeloencephalitis (EPM). Horses ingest infective sporocysts from hay, feed, or water fouled by opossum droppings, and there's no vaccine (University of Minnesota Extension). One forum member described losing a young horse to it and warned others to keep opossums out of the hay barn — hard-won advice worth heeding.

Layer 1 — Deny harborage at the site and the stack

Rodents need cover to feel safe. Take the cover away and most of them move on:

• Mow a bare perimeter. Keep a weed-free, mowed strip (aim for roughly a mowed 3-foot band, wider if you can) around the entire stack or barn. Tall grass and weeds against bales are a rodent highway.
• Clear the clutter. Old feed bags, scrap lumber, unused pallets, tires, and junk piles are nurseries. Remove them.
• Leave a wall gap. Don't jam stacks tight against barn walls. Leaving room (a foot and a half or so) lets you inspect, set traps, and keeps a hidden runway from forming between bales and wall.
• Mind your pallets. Elevating bales on pallets, railroad ties, or rock helps drainage and keeps the bottoms dry — but the void under a pallet is also perfect rat cover. Use the elevation for moisture control, then keep the perimeter open and baited so you're not building a fortress for rats. As one operator cautioned about storing on pallets, "there might be some concern with rats, so keep that in mind."

What about stacking on edge vs. flat?

You'll hear that standing round bales on end (strings off the ground) protects the twine. Some operators swear by it; others push back hard. One reported fixing 30–40 chewed bales in a single year that were all stacked on edge, arguing that mice simply climb up between the bales — whereas tightly stacked flat bales put too much weight between rows for mice to travel far, so "they might give up by the time they get to the strings." The honest takeaway: orientation alone won't save you. Tight, heavy, well-organized stacks help; the perimeter, predators, and baiting do the real work. For the full method see stacking net-wrapped bales in a barn and round-bale storage base prep.

Layer 2 — Keep it dry and up off the ground

Damp bottoms attract rodents and rot at the same time. Store on a well-drained base — rock, pallets, ties, or bridge decking — on the highest ground you have, and cover outdoor bales properly. Dry hay stored right resists both spoilage and nesting. Our guides on storing round bale hay, net-wrapped bale storage outside, and choosing a bale tarp walk through base prep and covering.

Layer 3 — Put working cats to work

Ask a room full of hay farmers how they keep mice out and you'll hear one answer more than any other: barn cats. Done right, they're the most reliable, lowest-cost control there is. The catch is that a working cat is not a well-fed pet.

• Keep them a little hungry. A common rule: a small amount of food to keep them from wandering, then cut it off when you see a mouse. "Four cats… get fed one cup twice a day unless I see a mouse, then no food for one to two days," one producer wrote. Overfed cats get "fat and lazy" and stop hunting.
• Get semi-feral, not lap cats. Shelters are full of barn-cat candidates. The ones with a bit of wild in them hunt; the couch potatoes wait to be fed.
• Numbers and turnover. A male and a female, left to their own devices, keep the population self-sustaining if coyotes or roads take a toll. Several cats on patrol is the goal.
• The "cats foul the hay" worry. Cats generally won't defecate on bales — they need loose ground to dig and cover, which stacked hay doesn't offer — so most operators report no scat on the stack. Some do note cats may urinate on hay; giving them accessible loose ground or bedding nearby, and not confining them to the stack, keeps that to a minimum.
• Bonus: no mice, no snakes. Farmers repeatedly note that once the mice are gone, the rat snakes that came to eat them leave too. (Those non-venomous snakes are on your side while they're around.)

A good farm dog earns its keep here as well — many are natural mousers, especially when you're moving the last bales out of a shed and the nest scatters.

Layer 4 — Traps and bait stations, used safely around feed

Predators knock the population down; traps and bait stations finish the job and hold the line. Near livestock feed you have to do this carefully:

• Use tamper-resistant bait stations only — never loose bait — around feed. Stations protect the bait from moisture and keep it away from livestock, pets, and non-target wildlife. Loose rodenticide near hay is a poisoning risk and a contamination risk.
• Space them to rodent travel. For mice, roughly 8–15 feet apart; for rats, 15–30 feet, along walls and known runways. Keep stations along travel paths but away from direct contact with feed and water.
• Inspect and refresh regularly — at least monthly, more often during an active infestation or after harvest — and rotate active ingredients so rodents don't build resistance.
• Add traps to the mix. Snap traps and electronic traps work well as part of an integrated program. Wear gloves, and remove dead rodents promptly in a sealed bag to limit disease exposure. Always follow the product label.
• Skip the folk remedies. Mothballs, urine-soaked twine, chili-pepper dips, and the like are ineffective outdoors and can be unsafe or illegal around feed. Spend the effort on exclusion, predators, and proper baiting instead.

Exclude the bigger wildlife (especially for horse hay)

If you feed horses, add an exclusion layer aimed at opossums and raccoons:

• Seal small entry points and keep barn doors and windows secure so wildlife can't get to stored hay and feed.
• Don't leave pet food out overnight, and clean up spilled grain promptly — both are opossum magnets.
• Store grain in closed, rodent-proof containers, and keep hay and feed off the ground and covered.
• Trim brush and overhanging branches near the barn that give wildlife an access route.
• Reject and discard any hay or feed that shows animal-dropping contamination rather than feeding through it.

Does net wrap or twine change any of this?

Not as much as people hope. Mice will chew "rodent-resistant" plastic twine right along with sisal when the hay is good enough. Net wrap isn't rodent-proof either — but because net comes off the bale in one connected sheet, a single chewed spot is less likely to let a bale slump the way a cut individual twine string can, and full-coverage net over a firm, dense bale gives rodents less loose surface to work into. It helps at the margins; it is not a substitute for the four layers above. If you're comparing options, our factory-direct XES Extreme Bale Net Wrap makes a tight, uniform bale that stacks and sheds water well — which is exactly the kind of dry, dense stack rodents find least inviting.

Bottom line: storage practice beats wrap choice. A dry, elevated, tightly stacked pile with a mowed perimeter, working cats, and monitored bait stations will out-protect any twine or net on its own.

A simple stored-hay rodent plan

1. Mow a bare perimeter and clear all clutter around the stack.
2. Store on a dry, drained, elevated base; leave a gap to walls; keep pallet voids from becoming rat cover.
3. Stack tight and heavy; cover outdoor bales.
4. Keep a few lean, semi-feral cats (and a mouser dog) on patrol.
5. Run tamper-resistant bait stations and traps along runways, away from feed; inspect monthly.
6. For horse hay, exclude opossums and reject any dropping-fouled hay.

Frequently Asked Questions

How do I stop mice from chewing the strings on my hay bales?

Attack it in layers: mow a bare perimeter and remove clutter so rodents lose cover, store bales dry and elevated with a gap to walls, keep lean working barn cats on patrol, and run tamper-resistant bait stations plus traps along runways away from the feed. Stacking tight and heavy helps; no single trick works alone.

Do barn cats really keep mice out of stored hay?

Yes, they're the most common and effective control farmers rely on — but only if they hunt. Keep cats lean (a little food to hold them nearby, cut off when you see mice), choose semi-feral cats over pets, and keep several on patrol. Well-fed, lazy cats stop working.

Is it safe to use rodent bait near hay and livestock feed?

Only in tamper-resistant bait stations, never as loose bait. Place stations along walls and runways, keep them away from direct contact with feed and water, space them to rodent travel (about 8–15 feet for mice, 15–30 feet for rats), inspect at least monthly, and always follow the product label. Remove dead rodents promptly with gloves.

Why are opossums a problem in a hay barn?

Opossums are the definitive host of the parasite that causes EPM (Equine Protozoal Myeloencephalitis) in horses. Horses become infected by eating hay, feed, or water contaminated with opossum droppings, and there is no vaccine. Exclude opossums from feed and hay storage, don't leave pet food out, and discard any dropping-fouled hay.

Does net wrap prevent rodent damage better than twine?

Slightly, but it's not rodent-proof. Mice chew both net and "rodent-resistant" twine on good hay. Net comes off in one connected sheet, so a chewed spot is less likely to collapse a bale than a cut twine string, and a tight full-coverage bale offers less loose surface to burrow into. Storage practice still matters far more than wrap type.

Featured photo: Bales in the Barn by Tony Atkin, licensed under CC BY-SA 2.0, via Wikimedia Commons. Inline photo: Hay store near Nutcombe Farm by Ivan Taylor, licensed under CC BY-SA 2.0, via Wikimedia Commons.