Everything You Ever Wanted to Know About Hornworms

Food for Thought

In recent years, the humble reptile has moved out of the desert and into the city as a common household pet. From iguanas to corn snakes, 4.5 million reptiles are kept in homes across America alone. Now, as increasingly popular as these pets are becoming, they do require a little more care than your average cat or dog when it comes to feeding. To keep your pet reptile happy, you’re going to need to supply it regularly with live food. Fortunately, when it comes to food that moves there’s no shortage of choices.

Live Hornworms and Other Delicacies

The most common types of live food you’re going to encounter are crickets, roaches, locusts, and various kinds of worms and grubs. The question being, if a chameleon could read the menu, what would it pick? The answer for most reptiles would be ‘hornworms, please’.

Hornworms — or goliath worms as they’re sometimes known — are large caterpillars that can grow up to 3-4” long. Bright green in color, they have a soft horn on their tail (hence the name) and come in two types: the tobacco hornworm (Manduca sexta)which is the larva of the tobacco hawk moth, and the tomato hornworm (Manduca quinquemaculata) which is the larva of the five-spotted hawkmoth. Although they’re quite similar in appearance, the tobacco hornworm has ‘V’ shaped markings down its sides, while the tomato hornworm has diagonal lines — plus, the tail spike on the tobacco hornworm is red as opposed to black. Aside from that, both hornworms are equally up to the job of being a tasty, nutritional meal for your pet reptile.

Although hornworms are full of protein and minerals like most feeders, what makes them particularly appealing to reptilian customers is their high moisture content (about 85%), which gives them their distinct plump appearance. This, when coupled with the fact that they have no hard outer shell or exoskeleton, makes them easily-digestible meals, especially for young reptiles or reptiles that are feeling unwell or dehydrated.

Now, as tasty as the hornworm may be, its plump appearance has led to a common misconception about its nutritional value. It’s often assumed that the hornworm looks the way it does because it’s full of fat. In fact, nothing could be further from the truth. Of all the common feeders, hornworms are the lowest in fat (only 3%), as opposed to wax worms (21% fat), mealworms (13% fat), phoenix worms (8% fat), and butterworms (5% fat). And as with all animals, we need to be careful how much fat reptiles consume in order to avoid health issues in later life.

Hornworms vs Other Live Food

It’s important to remember that variety is essential in all diets, including the diets of reptiles. Bearded dragon food, for instance, should constitute roughly 65% live food and 35% greens when the reptiles are young, and about 40% live food and 60% greens when they are adults. However, while most greens are safe for your reptile, the same can’t be said for live foods.

Firstly, we don’t want to give our reptiles food that’s going to fight back — and some food most definitely will. Crickets, for instance, can give your beloved pet a nasty bite. Even when dealing with insects that don’t have a violent streak in them, we need to be cautious. Dubia roaches are a common feeder, and while they don’t bite, their spiny legs can be very uncomfortable to eat, especially for younger reptiles. It’s for this reason that large worms, especially hornworms, are generally considered a better choice of live food.

Live Food as Opposed to Frozen

Freeze-dried food may sound like a convenient alternative to having to raise and look after live hornworms yourself, but there are some very good reasons why this approach shouldn’t be pursued. To start with, the moment an insect or worm dies, its nutritional value starts to break down. Although freeze-drying is possible, the moment the food reaches edible temperature again, the decomposing process restarts — and there’s no guarantee when your pet reptile is actually going to eat what you have left for it. It’s far better for your pet that the food is alive and well until your reptile gets hungry. What’s more, many reptile species won’t eat anything unless it’s moving — that’s simply how they have learned to identify food. Add this to the fact that reptiles are hunters and foragers, and we begin to understand that food that creeps and crawls is going to keep a pet reptile closer to its nature in the wild and happier in your home as a result.  

Wild Hornworms or Captive-bred?

When feeding reptiles, it’s generally considered a risky idea to give them anything caught in the wild — insects and larvae can carry all kinds of bacteria and viruses. The same rule applies when using hornworms. Although both species of hornworm feed on the same plants, the tobacco hornworm has a habit of storing the toxins found in the tobacco plant, making it a potentially deadly little treat for your pet.

Captive-bred hornworms, however, are raised on a nutritional wheatgerm diet which not only makes them safe reptile food but gives them their distinctive bright green color. This color is particularly significant as reptiles seem to find it hugely enticing. If you have a pet reptile that is a picky eater or seems to have lost its appetite for some reason, brightly-colored hornworms are likely to be a good way of getting them to eat again.

Looking After Hornworms

From the practical point of view of a reptile owner, hornworms have an advantage in that raising them at home is considerably simpler than raising other types of live food. Not only that, but most people are going to be far more comfortable having a cup full of caterpillars in their home than a bucket full of roaches.  

As mentioned before, it’s not a great idea to pick up hornworms in the wild, and you are best advised to go to a reputable breeder. When your hornworms arrive, they are likely to be small larvae (depending on what you’ve ordered) and can live quite happily together so long as there is enough food for them all (incidentally, for all you horror fans out there, if there isn’t enough food, the worms will start to eat each other). Given a healthy supply of wheatgerm though, the worms will grow quite happily — and quickly. In warm temperatures (70-80°F), a hornworm will nearly double its size every 24 hours. This is fine if you’re feeding large reptiles, but if you own small or younger reptiles, it’s best to keep hornworms at around 55-65°F, which will slow their growth and make them much easier meals. Which leads to a common question — how long do hornworms live? After a larva has hatched from its egg, it will eat and grow for between two to three weeks before it begins to pupate. It’s in this final week that they will be at their most succulent and nutritious.

Conclusion: Hornworms Should be at the Top of Your Menu

Whether it be iguana or chameleon food that you’re looking for, hornworms are a great live feeder to build a diet around. With a moisture content of 85%, protein 9%, fat 3%, and calcium 4.6% it hits many of the bases needed to keep your pet reptile healthy.

It’s important to remember though that staple feeders are not food types that you can use exclusively to feed your reptiles. Variety is the key to any healthy diet. Although hornworms can make up the bulk of a diet, they shouldn’t be used on their own. You may love sushi, but how long could you eat it before you start dreaming about a Big Mac? Reptiles are the same. But if you’re looking for a solid feeder that you can build your pet’s diet around, then hornworms are a great choice. If you’re a reptile, life doesn’t get much sweeter than that.