Hornworms for Ducks: A Keeper's Honest Guide to a Hydrating Treat

I keep feeder insects for reptiles and amphibians, and I also keep ducks — which means I get this question constantly: "Can I toss my ducks the hornworms?" The short answer is yes, carefully, as an occasional treat. The longer answer is that almost everything written about hornworms for ducks oversells them, and a couple of the claims floating around are flat-out wrong in ways that can hurt your birds.

So here's the honest version. Hornworms are not a protein supplement. They are a hydration and enrichment treat — basically a wriggling, bright-green water balloon your ducks love chasing. Used that way, on top of a proper diet, they're great. Used as a protein source or a daily staple, they'll let you down nutritionally. And used straight off your garden tomato plants, they can poison your flock. This guide walks through all of it: what hornworms actually are, what they really deliver, the toxicity rule you cannot ignore, how to size and portion them, how to source them safely, and how they stack up against the other feeders you might reach for instead.

What hornworms actually are

Hornworms are the larvae (caterpillars) of large hawk moths in the genus Manduca. The one you'll buy as a feeder is the tobacco hornworm, Manduca sexta — a fat, smooth, vivid blue-green caterpillar with diagonal side stripes and a soft little "horn" on its rear end (harmless; it doesn't sting). You'll often see them called "tomato hornworms," but that name technically belongs to a very close relative, Manduca quinquemaculata. They look nearly identical and both feast on nightshade-family plants. For a duck keeper the species name barely matters; what matters enormously is what the worm has been eating, which I'll come back to in the toxicity section because it's the single most important thing in this entire guide.

The reason hornworms are sold as feeders at all is their growth. They are eating machines. A hatchling barely visible to the eye balloons to a finger-length caterpillar in a couple of weeks, gaining mass faster than almost any feeder insect. Commercial producers raise them in cups on a green, prepared hornworm chow (a wheat-germ-based artificial diet), which keeps them clean, toxin-free, and on a predictable size curve. That fast growth is also why size management is a constant theme with hornworms: a worm that's the perfect bite today can be too big to feed safely in three days.

Why a duck keeper would bother

Ducks are enthusiastic, messy, opportunistic foragers. They love anything that moves, and a slow, soft, brightly colored caterpillar is irresistible to them. Three traits make hornworms genuinely useful in a duck's life:

• ◆They're mostly water. That's a liability if you're after nutrition and an asset if you're after hydration — more on this below.
• ◆They're soft. No hard shell, no spiky legs, easy for a duck to grab, gulp, and digest.
• ◆They're stimulating. A scattered handful turns feeding time into a foraging game, which is good for a duck's body and mind.

What they are not is a building block of the diet. Keep that framing and you'll use them well.

The nutritional reality (and the myths to drop)

This is where most hornworm-for-ducks advice goes sideways, so let me be precise. On an as-fed basis — meaning the worm as your duck actually eats it, water and all — hornworms run approximately:

• ◆Moisture: ~85%. Exceptionally high. This is the defining fact about hornworms.
• ◆Protein: ~9%. Low. Because so much of the worm is water, there's very little dry substance, and what's there isn't protein-dense by feeder standards.
• ◆Fat: ~3%. Low. Hornworms are a lean treat, which is one genuine point in their favor versus fatty feeders.

Notice what those numbers mean together: a hornworm is basically water with a thin protein-and-fat wrapper. That makes it a hydration treat, full stop. You'll see sources claim hornworms are "high in protein" and "rich in calcium" — both overstate the case. They are not a high-protein feeder, and like nearly every feeder insect they are phosphorus-heavy with a poor calcium-to-phosphorus ratio, so they are not a reliable calcium source either. If you read that hornworms will help your laying ducks build strong eggshells, treat that with real skepticism: eggshell calcium comes from the layer feed and supplemental calcium (like oyster shell offered free-choice), not from a watery caterpillar.

So let's bury three myths right now:

1. ◆"Hornworms are a great protein boost for molting ducks." They aren't. Molting ducks need more protein from a higher-protein feed; ~9%-protein water balloons won't move the needle. Hornworms can ride alongside a molt diet as a treat, but they don't power feather regrowth.
2. ◆"Hornworms are calcium-rich for layers." No. Poor Ca:P, not a meaningful calcium contribution. Use proper layer feed and free-choice oyster shell for shell quality.
3. ◆"Hornworms can be a main food because they're so nutritious." They can't. They're too watery and too nutrient-light to be a staple. Over-rely on them and you'll dilute the diet and likely cause loose droppings.

What hornworms are genuinely good for

Strip away the hype and there's a real, useful role left:

• ◆Hot-weather hydration. On a brutal summer day, a few hornworms deliver clean water in a form ducks eagerly take. Useful for birds that aren't drinking enough or are heat-stressed.
• ◆Enrichment and foraging. Scatter them and ducks hunt, which is good physical and mental activity.
• ◆A gentle, lean treat for sensitive birds. Soft-bodied and easy to digest, hornworms suit older birds or convalescing ducks that struggle with coarser foods — as an easy treat, not as the medicine that fixes them.
• ◆A low-fat alternative to richer treats. If you're already feeding fatty extras, a hornworm is a leaner way to reward and engage your flock.

That's the honest case for hornworms: hydration, enrichment, and a soft lean treat. Build your expectations there and you'll never be disappointed.

The one rule you can't break: never feed wild hornworms

If you take nothing else from this guide, take this: only ever feed commercially raised hornworms grown on prepared chow. Never feed wild hornworms picked off garden plants.

Here's why this isn't optional. Hornworms are specialists on the nightshade (Solanaceae) family — tomato, tobacco, potato, pepper, eggplant. Those plants are loaded with natural defensive toxins: solanine and related glycoalkaloids in tomato and potato foliage, and nicotine and tropane-type alkaloids in tobacco. The tobacco hornworm is famously tolerant of nicotine and can carry plant-derived compounds in its body. A wild hornworm is, in effect, a little tank of whatever toxic plant it's been chewing on. Feed that to a duck and you may be feeding it a dose of solanine or nicotine-class alkaloids.

This is the kernel of truth buried under the lazy "are hornworms toxic?" myth. The worm itself isn't inherently poisonous — but what it ate makes it poisonous, and a garden hornworm has been eating exactly the plants you don't want in your duck. Commercially raised hornworms sidestep the whole problem: they're grown on a clean, wheat-germ-based artificial diet with no nightshade toxins to accumulate. That's the entire reason "buy them, don't pick them" is the rule.

Two corollaries:

• ◆Don't raise feeder hornworms on tomato or tobacco leaves at home. People read that hornworms "naturally" eat tomato plants and decide to grow their own that way. Don't. If you raise them, raise them on commercial hornworm chow, or you've recreated the toxic-worm problem in your own garage.
• ◆Treat any "free" hornworm with suspicion. A neighbor's tomato-plant hornworms, worms from an untreated garden, worms of unknown origin — all of it goes in the trash, not the duck pen. The convenience is never worth the risk.

For a deeper read on the biology of Manduca sexta and its nightshade host plants, the University of Florida's entomology and nematology department maintains good non-commercial species information. When you're ready to feed, source from a supplier that raises worms on chow — All Angles Creatures stocks commercially raised hornworms grown specifically as clean feeders, which takes the toxicity question off the table entirely.

The hornworm life cycle, and why size changes day to day

To use hornworms well you have to understand how fast they move through their life cycle, because it directly drives the sizing problem that follows.

A hornworm starts as a tiny egg laid by a hawk moth. The hatchling caterpillar is barely a few millimeters long. From there it does almost nothing but eat, molting through a series of stages (instars) and roughly doubling in mass at each one. In ideal warm conditions on rich food, it goes from pinhead to a fat 3-to-4-inch caterpillar in only a couple of weeks. After that it stops eating, often darkens, and burrows down to pupate — the stage that eventually becomes a moth. As a feeder you're using the caterpillar stage, and you're racing its growth curve the whole time.

What this means in practice:

• ◆A cup of "small" hornworms becomes a cup of "too big" hornworms shockingly fast — sometimes in two or three days at warm room temperature. There is no "set it and forget it" with hornworms the way there is with a roach colony.
• ◆You manage size with temperature. Cooler temperatures (the cool side of room temperature, not refrigerator cold) slow the growth curve and buy you more days at a duck-appropriate size. Warmth accelerates everything.
• ◆Plan to use them quickly. Buy hornworms close to when you'll feed them, in a size already appropriate for your ducks, and don't stockpile them expecting them to wait for you. They won't.

Understanding this curve also explains the toxicity rule from a different angle: commercial producers control that explosive growth on a clean, prepared chow precisely so the worms are predictable, sized, and toxin-free. A wild hornworm is the same growth machine running on poison plants.

Size matters: choke and impaction risk

The second-biggest hornworm hazard, after toxicity, is size. Because hornworms grow so fast and so large — a mature one can hit 3 to 4 inches — they very quickly outgrow what a duck can safely swallow. An oversized hornworm is two problems at once:

• ◆Choking. A worm too big to go down cleanly can lodge in the throat, especially for smaller breeds and younger birds.
• ◆Crop and gizzard impaction. Even if a too-large or too-bulky worm goes down, a big slug of soft tissue can sit poorly. Ducks process food with a muscular gizzard aided by grit, but they aren't built to handle a 3-inch caterpillar in one go.

The fix is simple and non-negotiable: size the worm to the duck.

• ◆Feed small to medium hornworms to ducks. Save the giants for larger reptiles, not poultry.
• ◆Cut larger hornworms into bite-sized pieces before offering them to smaller breeds or to any bird you're unsure about.
• ◆Always offer grit free-choice to ducks eating any whole prey, so the gizzard can do its job.

Because hornworms balloon in size day to day, get into the habit of looking at the worm before each feeding rather than assuming last week's size is this week's size.

Which ducks, and at what age

Most standard domestic ducks handle hornworms fine as an occasional treat — the hearty, omnivorous breeds (Pekin, Muscovy, Rouen, and similar) take them happily. The variables that actually matter are size of the bird and age, not breed per se:

• ◆Adult, full-grown ducks: Fine to offer appropriately sized hornworms as a treat. Larger birds can take medium worms; smaller breeds (bantams, Call ducks) should get small worms or cut pieces and smaller portions.
• ◆Well-grown juveniles: Can have the occasional small, soft hornworm, sized down and fed sparingly. Their diet should still be dominated by a proper grower feed.
• ◆Young ducklings: I skip hornworms entirely. Ducklings need a precisely balanced starter feed for rapid early growth, their digestion is still developing, and an oversized worm is a genuine choke risk. There's simply no upside that justifies it at that age.

If a particular bird has a health condition, is on a vet-managed diet, or you're otherwise unsure, check with an avian or livestock vet before adding any new treat. Treats are the easy thing to get wrong precisely because they feel harmless.

How much, how often: a portion plan

Hornworms are a treat, and the portion plan reflects that. The high moisture content is the practical limiter: feed too many and the first thing you'll see is loose, watery droppings, because you've essentially overloaded the bird with water and bulk.

My working guidelines for healthy birds on a complete diet:

• ◆Adult ducks: 2–4 appropriately sized hornworms per bird, once or twice a week, fed on top of their regular feed.
• ◆Juveniles: 1–2 small hornworms, no more than once a week, and only once they're well-grown.
• ◆Ducklings: none.

Layer those treats into a complete diet, never instead of it. A duck's day should be built on a complete commercial waterfowl/poultry feed appropriate to its life stage, with clean water always available, plus greens and forage. Hornworms are the sprinkle on top, not the meal.

A few feeding mechanics that make life easier:

• ◆Feed fresh and alive when possible. Live worms trigger the foraging response and are at peak quality. Discard any that have died and gone soft or discolored.
• ◆Scatter for enrichment, or use a dish. Scattering small worms in a foraging area turns the treat into activity. For arboreal-style picky eaters this doesn't apply to ducks, but a shallow dish helps if you want to control exactly who gets what in a mixed flock.
• ◆Don't leave live worms loose and unattended. A hornworm dropped in bedding can crawl off; feed what the birds will eat promptly and clean up stragglers.
• ◆Rinse before feeding. Even clean, commercially raised worms get a quick rinse under fresh water to remove any chow residue.

Introducing hornworms to a flock the right way

Ducks are neophobic about food in unpredictable ways — some birds pounce on a new treat instantly, others eye it with deep suspicion. A calm, staged introduction avoids both waste and digestive upset.

1. ◆Start tiny. Offer just one or two small hornworms to the flock, not a generous handful. You're testing both acceptance and tolerance.
2. ◆Pair it with the familiar. Drop the new worms near or alongside a treat or feed the ducks already know and love. Curiosity plus familiarity overcomes hesitation faster than a strange food sitting alone.
3. ◆Let the bold birds lead. In any flock there's a duck that tries everything first. Once one bird grabs a hornworm and clearly enjoys it, the rest usually follow within minutes. You don't have to convince every duck individually.
4. ◆Watch the next day's droppings. Because hornworms are so water-rich, the first sign you've offered too many is loose stool. If droppings stay normal after a small introductory serving, you can step up to a normal treat portion.
5. ◆Build to the routine slowly over a week or two, not all at once. By the end you should be at the steady-state portion plan: a few worms, once or twice a week.

This staged approach matters more with hornworms than with drier treats specifically because of the moisture. Dumping a big first serving on an unaccustomed flock is the fastest way to get watery droppings and conclude (wrongly) that hornworms "don't agree" with your ducks. They do — in the right amount.

Situations where hornworms genuinely earn their place

Used as the hydration-and-enrichment treat they are, hornworms shine in a handful of specific scenarios. These are the times I actually reach for them:

• ◆Heat waves. When summer temperatures spike and you're worried about birds staying hydrated, a few hornworms deliver clean water in a form ducks eagerly take, on top of their normal water sources. Think of it as hydration insurance with a side of fun, not as a replacement for ample drinking water.
• ◆Foraging enrichment for confined or bored birds. Ducks kept in smaller runs benefit from foraging activity. Scattering small hornworms in a foraging area turns a passive afternoon into active hunting — good for body and mind.
• ◆Tempting a soft or fussy eater. A bird that's a bit off its feed or recovering can sometimes be coaxed into interest with a soft, eye-catching treat. Hornworms work here as an appetite spark, not as the nutritional support a sick bird actually needs — that comes from proper feed and, when warranted, veterinary care.
• ◆Training and tameness. Because ducks love them so much, hornworms (sized and portioned correctly) are a strong reward for getting birds to come when called, accept handling, or move where you want them.

Notice that none of these are "to meet a nutritional requirement." Every legitimate use of hornworms for ducks is about water, behavior, or palatability — never about protein, fat, or calcium. That framing keeps you honest about when to use them.

Can you raise feeder hornworms at home?

You can, but only one way safely: on commercial hornworm chow, never on garden plants. If you're tempted to raise your own to save money, the entire viability hinges on getting this right.

The safe approach is to buy hornworm eggs or tiny hatchlings plus a supply of the wheat-germ-based artificial chow producers use, and raise them in a clean, ventilated container at warm temperatures with the chow as their only food. Kept this way, the worms grow fast, stay clean, and accumulate no plant toxins, because they never touch a nightshade leaf.

The unsafe approach — and the one you must never take — is raising hornworms on tomato, tobacco, potato, or pepper foliage because it's "natural" or free. Do that and you've manufactured exactly the toxic worm this guide warns against. The plant defenses (solanine, nicotine-class alkaloids) end up in the caterpillar, and from there in your duck.

Honestly, for most duck keepers home-rearing isn't worth it. Hornworms are an occasional treat, not a staple, so you don't need volume; and the fast growth means a home batch all hits "too big" at once unless you stagger and temperature-manage carefully. For most people, buying small batches of commercially raised worms as needed is cheaper in effort and far safer. Reserve home-rearing for keepers who also feed reptiles and already run a chow-based operation.

A simple seasonal approach

Hornworms fit a duck's year differently by season, mostly through that hydration lens:

• ◆Summer: Their best season. Hot-weather hydration and foraging enrichment make hornworms genuinely useful. Keep portions in check so loose droppings don't compound heat stress, but this is when they pull real weight.
• ◆Spring and fall: Fine as an occasional enrichment treat. Hydration is less of a concern in mild weather, so they're more "fun" than "function" — still good, just less needed.
• ◆Winter: Least useful. Cold-weather birds need calories and warmth, and a watery, low-fat, low-protein treat does little for that. If anything, a richer treat (in strict moderation) does more in the cold. Hornworms aren't harmful in winter, just largely beside the point.

Across every season the constants don't change: clean commercial source, correct size, modest portions, on top of a complete feed.

Reading your ducks: good signs and warning signs

Whenever you add a new treat, watch the birds for a few days. With hornworms specifically:

Going well looks like: eager interest and active foraging, normal firm-ish droppings, steady appetite for their regular feed, and calm, normal behavior. A duck that hunts down its hornworms and then goes back to its pellets is a duck using them correctly.

Going poorly looks like: watery or runny droppings (the classic sign of too many high-moisture worms), going off their normal feed (a sign treats are crowding out real food), or any lethargy or distress. If you see loose droppings, cut back the quantity or frequency — it's almost always simply too much water-rich treat. If you see anything more serious than mild loose stool after introducing hornworms, stop feeding them and consult a vet, particularly if there's any chance the worms weren't from a clean commercial source.

The biggest "poorly" risk by far isn't a subtle nutritional drift — it's the two things this guide keeps hammering: a toxic wild worm or an oversized worm. Source clean and size correctly, and the day-to-day signs almost always stay in the "going well" column.

Getting more out of hornworms: gut-loading and pairing

Because a hornworm is mostly water, there's a limit to how nutritious you can make one — you can't turn a water balloon into a protein bar. But two simple habits squeeze more value out of the treat.

Gut-loading, lightly. "Gut-loading" means feeding the feeder something nutritious shortly before it becomes a meal, so whatever is in its gut gets passed up the chain. Commercially raised hornworms arrive already eating their wheat-germ chow, which is a perfectly fine baseline; you don't need to do anything elaborate. The main thing is not to let them sit and empty out — feed worms that have been actively eating their chow rather than ones that have gone hungry for days. Whatever modest nutrition the worm carries is highest when it's well-fed at the moment your duck eats it.

Pairing for balance. The smarter move is to use hornworms as part of a varied treat rotation rather than alone. On a hot day, a few hornworms for hydration alongside a more nutritionally complete treat (like black soldier fly larvae) gives your ducks both the water and the actual nutrition. The hornworm does the hydration job it's good at; the BSFL covers the calcium and protein the hornworm can't. Variety across the week — different treats on different days, all on top of complete feed — beats leaning on any single insect, hornworm included.

What you should not do is try to make hornworms "complete" by feeding more of them. More hornworms just means more water and more risk of loose droppings; it doesn't add the protein, fat, or calcium that simply isn't there. The fix for "hornworms aren't very nutritious" is a different food, not more hornworms.

Portioning by breed and size

The headline portion plan — a few worms, once or twice weekly — is the right default, but real flocks are mixed, and bird size genuinely changes the math:

• ◆Large breeds (Pekin, Rouen, Muscovy and similar): Comfortable with medium hornworms, and can take the upper end of the portion range (toward 4 worms per session). Their size makes choke risk lower, but you should still avoid the full-grown 3–4-inch giants.
• ◆Mid-size breeds (Welsh Harlequin, Khaki Campbell, runners and similar): Small to medium worms, middle of the portion range. Watch droppings, since smaller-framed layers can show the water-overload effect sooner.
• ◆Bantams and small breeds (Call ducks and other small varieties): Small worms only, or cut pieces, and the low end of the portions (1–2 per session). Their petite frames and smaller throats make sizing and restraint especially important.
• ◆Mixed flocks: Feed to the smallest and youngest bird's safe limits, or hand-feed/dish-feed so a greedy big duck doesn't gulp a worm meant — and sized — for a smaller one. Scattering works for enrichment but gives you less control over who eats what; in a mixed flock with very different sizes, more controlled feeding is safer.

Across every breed the universal rules hold: clean commercial source, size the worm to the bird, modest portions, complete feed as the foundation, and grit always available.

Hornworms vs. other duck treats: an honest comparison

Hornworms aren't the only insect or protein treat you can offer ducks, and they're rarely the best one for a given goal. Here's how the common options compare. Treat these as approximate, as-fed figures — real values shift with source, diet, and life stage — but the relationships are what should drive your choices:

The takeaways that actually matter for a duck keeper:

• ◆For hydration and enrichment, hornworms win — nothing else delivers clean water in a treat ducks love this much.
• ◆For a nutritional treat, black soldier fly larvae are the smarter pick. They're the one common feeder with a genuinely favorable calcium ratio, which makes them especially friendly to laying birds. If your goal is "give my ducks something that's actually good for them," reach for BSFL, not hornworms.
• ◆Mealworms are fine but fatty — fun, palatable, easy to overdo. Portion them like the rich snack they are.
• ◆No single insect is a staple. Every option here is a treat that rides on top of a complete waterfowl feed. The point of variety is engagement and balance, not replacing the base diet.

In other words: pick the treat to the goal. Hot day or a bird that needs encouragement to take in water? Hornworms. Want a treat that quietly improves nutrition? BSFL. Just want to make feeding time fun? Any of them, in rotation, in moderation.

Where hornworms fit in a duck's whole diet

Zoom out and the picture is simple. A healthy domestic duck eats, in rough order of importance:

1. ◆A complete commercial waterfowl or poultry feed matched to life stage (starter, grower, layer/maintenance). This is the non-negotiable foundation — it carries the protein, the balanced amino acids, the vitamins, and (for layers, alongside free-choice oyster shell) the calcium.
2. ◆Clean, ever-available water. Ducks need water not just to drink but to wet their food and keep their bills and eyes clean.
3. ◆Greens, forage, and appropriate vegetables. Pasture, leafy greens, and safe garden scraps add variety and natural foraging.
4. ◆Grit, free-choice, so the gizzard can grind whole foods including any insects.
5. ◆Treats — including hornworms — in moderation, sitting on top of all of the above and never displacing it.

Hornworms live on that last rung: a couple of times a week, sized correctly, sourced clean, offered for hydration and fun. Get the first four rungs right and the treats can only help; get them wrong and no amount of hornworms will fix it.

It helps to be concrete about what those first rungs actually require, because it shows why a ~9%-protein water balloon can't substitute for any of it:

• ◆Ducklings need a high-protein, balanced starter feed (often around 18–20% protein) for their explosive early growth, ideally one formulated or supplemented appropriately for waterfowl. Their requirements are tight and time-sensitive; this is exactly why I don't feed them hornworms at all.
• ◆Growers transition to a slightly lower-protein grower feed as they mature, still nutritionally complete.
• ◆Layers need a layer feed with adequate protein plus enough calcium for shell formation, almost always with free-choice oyster shell offered on the side so each hen can take what she needs. This is the calcium pathway — not insects.
• ◆Maintenance/non-laying adults need a complete maintenance ration that isn't overloaded with the calcium layers require.

Against that backdrop, the role of a treat is obvious: it adds variety, hydration, and enrichment at the margin, while the formulated feed does the actual nutritional work. A treat that's mostly water can ride along on top of any of these life-stage diets without disrupting them — but only if it stays a small fraction of intake. The moment hornworms start displacing meaningful amounts of feed, you've traded a balanced ration for water, and the bird pays for it.

For a sibling read, I've written a parallel guide on whether hornworms are safe for chickens — the toxicity and sizing logic carries straight across to poultry generally. And if you keep reptiles too and want to understand where hornworms genuinely shine (hydration treats for dehydrated or impacted reptiles), see the nutritional benefits of hornworms for reptiles.

Storing and handling hornworms at home

If you buy hornworms for occasional duck treats, you'll usually get them as small-to-medium worms in a cup with chow. A few notes so they last:

• ◆Keep them in their cup. Commercial hornworm cups are designed with the chow on one surface and a vented lid; the worms feed and climb inside. Don't decant them into bedding or open dishes for storage.
• ◆Cool slows growth; warmth speeds it. Hornworms grow explosively at warm temperatures. If you want to slow them down so they stay duck-sized longer, keep them on the cooler side of room temperature (but not refrigerator-cold, which can harm them). Warmer rooms mean you'll need to feed them off faster before they get too big.
• ◆Watch for size creep. Because they grow so fast, plan to use a cup of feeder hornworms within days to a couple of weeks, not "whenever." A cup of perfect-sized worms becomes a cup of too-big worms quickly.
• ◆Cull the dead. Remove any worm that's died, darkened, or gone mushy — never feed those.
• ◆Wash up. Rinse worms before feeding and wash your hands after handling cups and chow.

The short version

Hornworms are a hydration and enrichment treat for ducks, not a protein source and not a staple. They're roughly 85% water, ~9% protein, ~3% fat, with a poor calcium ratio — so they engage and hydrate your birds but can't feed them. Two hard rules keep them safe: only feed commercially raised worms grown on chow (wild hornworms accumulate solanine and nicotine-class toxins from nightshade plants and can poison your flock), and size the worm to the duck (a 3–4-inch worm is a choke and impaction risk; feed small-to-medium or cut larger ones). Offer a few, a couple of times a week, on top of a complete waterfowl feed with free-choice grit and water. Do that and hornworms become exactly what they should be: a fun, hydrating, low-fat treat your ducks will sprint across the yard for — and nothing more dangerous than that.

Building out a feeder rotation? See whether hornworms are safe for chickens, how hornworms serve reptiles as a hydration treat, or browse the full feeder care library for the rest.