Hornworm Care and Breeding

After reading many posts asking for help breeding hornwoms or lamenting over failed attempts at rearing or breeding I decided to write an instruction manual of sorts. Keep in mind this is just from my experience and not intended to be the end all be all of hornworm care and breeding.

Let us begin with the egg.

You might decide to buy eggs in order to be more economical and wonder, ok now what?

First you will want to be sure you have a deli cup with hornworm chow inside (I use chow from Great Lakes Hornworms or Mulberry farms usually). You can place the eggs on the lid of the cup and then put the cup on and allow them to hatch at room temperature or a bit higher. I keep all of my feeders in a room of the house that is kept at 75-80 degrees to maximize growth.

If you don't have a deli cup you can try to just put the eggs in a Tupperware with some screen or gutter guard (comes in a roll from lowes) Link to Lowes Gutter Guard and just be sure they can make it up to the food.

I make my own deli cups. I order cups with mesh lids and then use the gutter guard and twist ties. This also makes it easy for me to pull out the entire mesh and food when I am ready to transfer the worms to a bigger container.

The worms will hatch and climb up to the food in the cup.

I allow them to grow in the cup until they are large enough to move. I make sure to take the lid off to dump the frass everyday and also inspect the food for mold or bacteria. If you see any mold, white milky spots or a film on the food you will want to get them transferred out of the cup as soon as possible to avoid a total loss of worms. I have read that in the case of mold you can just remove the mold spot, but I don't take any chances.

If you need to slow down the growth of the worms in order to prolong the time you can feed them, you can put them in the refrigerator. I usually put them in a mini frig I have set at 50 degrees. I have read that they can go in for up to 2 days; however I have never put them in for more than a day at a time. I will put them in for a day and then leave them out for a day.

When the hornworms grow big enough to move, I then transfer them from  the deli cup to a modified tupperware container. I use the sterilite 6Qt (5.7 L) Tupperware containers that state they are for shoe storage.  Any Tupperware that is around that size should do.  I then cut out the lid and hot glue some screen to it as shown below.  I also cut some gutter guard (Link to Lowes Gutter Guard) to place in the bottom. I also put bottle caps in the bottom to raise the gutter guard up. This layer of gutter guard allows the frass to fall through and makes daily cleaning easier.

This is where I will grow the worms while they are fed off and until they are ready to pupate.

I store the hornworm chow in the refrigerator and only put enough for them to eat each day in the container. This helps to ensure the food is fresh and does not get contaminated. When I add fresh food I remove all of the old food and clean the container. Proper cleaning and maintenance will ensure healthy hornworms.

I also take out a few that I plan to feed off within the next couple days and gut load them with greens, squash, carrots and red bell peppers. They will readily eat many of your typical gut loading veggies.

If you plan to breed them you may also want to keep them on a light cycle. Longer days, around 14 hours, promote more rapid development. Shorter days, 12 hours or less, could result in them going in to diapause once pupated and this could last for months. I keep the last stage of the worms and the pupae in a screen cage with a light on top set to 14 hour days to ensure the pupae do not go in to diapause.

I usually separate my hornworms in to two groups, the ones that will be feeders and the ones I will use for breeding.

After you have grown your hornworms to full size you may wonder what to do when it is time to pupate. You might even wonder how to tell when they are ready to pupate.

The hornworms will grow to over three inches prior to pupating.

Once they reach this size there will come a time when they stop eating and start roaming around. They will then change to a lighter color and you can see the vein pulsing on their back. This is when they are ready to go in to the dirt.

There are many options for substrate, I prefer to use eco earth. Some people also use soil, moss or I have heard of just using paper towels to keep them. I have had the best experience using eco earth. When they are ready just put them in the container that has the moist substrate and they will burrow when ready.

Some may burrow immediately while others may take a day or two. I usually keep the dirt containers in a large bin as they tend to roam all over during this stage and will climb out of the container. They can roam around for a couple of days before finally staying put in the dirt.

After burrowing they will slowly begin to pupate. They will change from green to brown and eventually harden. It is very important to mist the dirt daily to ensure proper development of the moths. One major result of failing to keep them moist is stunted wing development in moths. If the moths have stunted wings they will not be able to fly and will not survive. You may also want to arrange a light as a longer day cycle (14 hrs) will result in faster moth development. If they are on a short day cycle (12 hrs) the pupae could go in to diapause that can last for months. As stated above, I keep the final stage of worm and the puapae in the screen cage that I use for the moths.

I usually dig my pupated worms up after about a week or so and transfer them to new containers of fresh dirt. I do this because I have lost entire batches due to a worm that burrowed only to die and rot or due to feces being in the soil and molding. Many times that I do this I do indeed find a dead worm in the soil.

About 3-4 weeks after the hornwoms pupate they will be ready to hatch in to hawk moths. You will want to be sure you have a cage or some other equivalent set up ready. I use a small repti breeze screen cage. I have a stick across the top to tie the humming bird feeder to and I line the walls and floor with plastic used when painting, as the moths can be pretty messy. The moths expel a liquid (meconium) when they emerge which can be messy. They can also kick up the dirt from the pupae tray while flying around. I do not put the humming bird feeder in the cage until I see a moth emerge.

The moths require the humming bird feeder in order to eat. It is best to use commercially available humming bird food from your local grocery store, hardware store or walmart. Attempting to mix your own solution could result in death of your moths.

When the moths first emerge, they will have small wings, once they climb up the screen they will sit there and puff out their wings to their full size. They do this pretty quickly, so if you see a moth the next day that has small or wrinkled wings, they likely are deformed and wont puff out to their full size. These moths will die pretty fast as they cannot eat.

Here is a moth drinking from the feeder.

Video of Moth Drinking

I also place a small potted tomato plant in the cage for them to lay their eggs on. The moths will breed by attaching their abdomens together and then the females will lay tons of eggs all over the plant and even on the cage walls and hummingbird feeder. It will be important to pick the eggs daily or they could get out of control. You can use other plants, however I have found that I get more egg with tomato plants.

The eggs will be small and green, but they are fairly sturdy and easy to collect.

Now for our hand at an artistic hornworm photo shoot.

And of course one of our boys with a hornworm

They even love to eat the Moths