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Raising Megaphasma denticrus (Phasmida: Diapheromeridae) from Egg to Adult




Megaphasma denticrus (Stål, 1875)
generic name: mega (Greek) = large; phasm (Greek) = apparition, phantom
specific epithet: dent (Latin) = tooth; crus (Latin) = cross

adult male and female:



Megaphasma denticrus or "giant walking sticks" are the largest of the Nearctic phasmids (Stark and Lentz, 1986). Their "superpower" is their superb ability to camouflage through plant mimicry. Females are larger than males with one study finding that females measure around 105-135 mm while males range around 90-125 mm (Maginnis et al., 2008). Other sources indicate that females can be as long as 15 cm. My largest F1 adult females measured nearly 16 cm.

This female died naturally late the season:



Megaphasma denticrus have chewing mouthparts and feed on the foliage of trees, vines, and grasses. They are nocturnal, remaining active at night and quite still so as to be undetected in the day.

Both males and females have femoral spines on the mid and hind legs, with males having a single large spine and females having a row of small spines (Maginnis et al, 2008). Males additionally have a ridge of tiny spines inside the middle femora (McMonigle and Clausen, 2002).

If you have the privilege of encountering this species in the wild, I highly recommend that you consider practicing ethical treatment of them in order to ensure that future generations will have the opportunity to know this unusual species. To start a colony, you only need three to four adult pairs. Be prepared to keep no more than eight Megaphasma denticrus in each 4-foot-tall cage. Rearing these insects requires several large cages in order to maintain an F1 generation in which your animals are comfortable and able to thrive. If you are caring for a few adults without rearing, please consider collecting the eggs and returning them to the forest floor in their natural habitat. Should this species become threatened or endangered, our knowing how to rear them might help with preservation.

I recommend considering this species if you have plenty of space for very large butterfly cages, at least 4 feet tall for up to eight individuals. In addition, you will need suitable potted plants and cuttings to place in the cages, and you should be committed to daily care. With these considerations, you will be able to enjoy a successful rearing experience.

My initial adults were collected in a forested habitat on Quercus stellata (Post Oak), Celtis laevigata (hackberry), Prosopis glandulosa (honey mesquite), and Sideroxylon lanuginosum (Gum bumelia). Interestingly, the eggs of Megaphasma denticrus somewhat resemble the seeds of Gum bumelia.

I began with four pairs of adults in order to start a colony and I kept them in a very large mesh butterfly cage. In this article I will describe rearing these beautiful phasmids through the following sections: 1) Housing and Care, 2) Life Cycle, 3) Care for Hatching Nymphs, 4) Mating, 5) Laying Eggs and Egg Care, and 6) Behaviours.


Adult munching hackberry leaves:




Housing and Care


CAGES

The cages that I use for Megaphasma denticrus are large mesh butterfly habitats, measuring 48"x36"x36". I use one large cage for every eight adults. Each cage has full spectrum lighting on it, pointing down toward the plants, for eight hours a day. In addition, natural lighting comes in through the numerous windows so the photoperiod inside resembles that of outside. (I do not use overhead lights at night.)

The vinyl bottom of the cage is covered with four layers of newspaper, changed out regularly for cleanliness.

I place potted plants inside the cage to give my animals a place to climb and food to munch. In addition, I add cuttings daily to the soil of the potted plants and replace them each morning with fresh cuttings.

The cage is lightly misted each evening, adding droplets for the Megaphasma to drink.

Fresh water is also provided in dishes with cellulose sponges.

Adult Cages:


Nymph Cage: (the eggs remaining to hatch are in the middle on a paper towel)



Cage Cleaning

Use caution when opening the cages as your phasmids might try to sneak out. I once found one who had made it all the way to the kitchen sink to have a drink of water. Since regular cage cleaning is absolutely required (removing everything from the cage to clean), it is important to use "holding cages" for everything and everyone removed. Always have a spare cage of the same size to use as a holding cage while you are cleaning. What I do, however, is move the dirty cage to the side, set up a fresh new cage where the dirty cage was, and move all the plants and animals and food/water from the dirty cage to the clean cage.


Hospice Care

When adults grow old and become too weak to climb plants, I move them to Assisted Living and later Hospice cages where they have easy access to food and water. I place their cuttings at the bottom of the cage where they can crawl to them. In addition, I provide nectar sponges (half clear Gatorade / half water soaked in cellulose sponges).

This very old adult crawled to her nectar sponge and drank:


This female was in a hospice cage for 30 hours before passing away. To my amazement, she managed to lay 15 eggs in those 30 hours!



FOOD

Note: Food at different stages will be discussed further in the Life Cycle section below.

Megaphasma denticrus in captivity can be rather picky eaters; however, it's possible to find their favourite foods which will vary as they age.

List of foods that I used:

* Rose
* Ulmus crassifolia
* Salix nigra
* Celtis laevigata
* Quercus buckleyi
* Quercus stellata
* Sideroxylon lanuginosum
* Vitis mustangensis
* Salix matsudana x alba (hybrid willow, purchased online for emergency food)
* supplemental organic romaine lettuce and apple slices
* fresh water

Munching VIDEOS:

VIDEO of Megaphasma denticrus munching hackberry leaf with the nighttime music of my rearing room.

VIDEO (continued) of Megaphasma denticrus munching hackberry leaf with the nighttime music of my rearing room.

VIDEO close-up of Megaphasma denticrus munching hackberry leaf.

VIDEO of Megaphasma denticrus munching oak leaf.

VIDEO of Megaphasma denticrus munching hackberry leaf.

VIDEO of Megaphasma denticrus munching hackberry leaf.



Life Cycle


Megaphasma denticrus are hemimetabolous, progressing from egg to nymph to adult.


EGGS

Stark and Lentz (1986) offer SEM (scanning electron microscopy) images of the M. denticrus egg with a detailed description and describe the capitulum (egg cap) as the "hollow dome" type. They describe the bicoloured egg as 3.9 mm long (including capitulum) and 2.0 mm wide with an "irregular surface texture due to closely packed, fine tubercles." These ootaxonomy studies are useful in assisting with systematics.

With my initial collected adults, I began gathering eggs at the end of May, 2022.

My first three eggs collected:


The eggs I picked up averaged 4.0 to 4.5 mm:


After the first ten days, I had collected quite a few eggs, and this continued throughout the season so that I had a very large number of eggs. (For this reason, you will want to limit the number of adults you initially collect because you will get more than enough eggs from three pairs of adults.)

Eggs from the first ten days and first three weeks:


Eggs overwinter and, in my area, hatch in spring. (I think it is possible that some eggs hatch in the second spring.) I collected all of the eggs from my 2022 adults and placed them in a container on a paper towel where they spent the winter. I used a very light fine-mist spray on them every few days.



NYMPHS


one-day-old nymph:


two-day-old nymph:



Diet and Care

I had read that first-instar nymphs require willow and that without it, they will "fall over dead" (McMonigle and Clausen, 2002), so I collected some Salix nigra (Black Willow) cuttings in fall in hopes of having some leaf out in late spring. (Take cuttings of your native willow species, at least 12 inches long, in late fall and let root in water to plant in pots or simply plant directly in potted moist soil (to place inside your cages). No rooting hormone needed. Keep moist.)

To my utter shock, my first eggs hatched on February 15, 2023, much earlier than I had expected. Of course, there were no willow leaves in the dead of winter, so my first step was to panic. After completing Step One, I moved on to Step Two, which was to try one of everything I had in my yard and to order some emergency Willow hybrid starts online because they were easily available.

To my delight, I found that the information on feeding young nymphs willow lest they die was incorrect. Mine readily ate rose leaves, cedar elm leaves, and hackberry leaves, and they thrived. To a lesser degree, my first-instar nymphs would accept oak species, the hybrid willow I was able to purchase and start, and even romaine lettuce.

first-instar nymph munching on rose:


nymph munching on white oak sp.:


This little cutie has been munching rose:


Interestingly, as nymphs got older, they got considerably pickier about their food. Mine only wanted Celtis laevigata (hackberry) and Quercus buckleyi (an oak that I have growing in the yard). They were no longer interested in the cedar elm or rose that they had enjoyed in their early childhood.

nymph munching on hackberry leaf:


VIDEO of first-instar nymph munching oak leaf


Growing Up


My nymphs hatched beginning on 02.15.2023, with the last one born on 03.04.2023. Nymphs appear to moult through four to five instars before the adult stage.

My first-instar nymphs, hatching beginning 02.15.2023, appeared to grow from around 10mm to 22-25mm.
My second-instar nymphs first appeared on 03.08.2023 and averaged around 32 mm.
My third-instar nymphs first appeared on 03.21.2023, starting at around 42 mm.
My first fourth-instar nymphs first appeared on 04.03.2023, at around 74 mm.
What might have been fifth-instar nymphs began appearing on 04.19.2023 at up to 90 mm.
Adults first moulted on 05.02.2023, with my final F1 adult moulting on 05.30.2023.

First-instar nymph:


Second-instar nymphs, younger and older:


Late first-instar vs. late second-instar nymphs:


Third-instar nymphs: freshly moulted to third instar, early third instar, and later third instars:


Comparison of first-instar, second-instar, and third-instar nymphs:


Fourth-instar nymph:


After fourth instar, things got fuzzy and I was not able to distinguish fourth- from fifth-instars (if there is a fifth instar), but this one might be a fifth-instar nymph:



Moulting

Fortunately, this species moults with relative ease compared to other insects. Of course, your rearing cages must provide plenty of room for your nymphs to develop, moult, and grow properly.

Images of Megaphasma denticrus moulting:





Moulting Series:





VIDEO of Megaphasma denticrus moulting. (Note: Video is horizontal, but the moult, of course, occurs vertically.)



Freshly moulted nymph, eating exuvia:



Megaphasma denticrus generally eat the exuvia after moulting, but sometimes the exuvia may fall or they may abandon it.

exuvia:




ADULTS

My first adult moulted on 05.02.2023 with the first mating on 05.12.2023, and first eggs laid about ten days later.

This is my first adult (male) at 12 cm:


Here is a female at 13 cm:



While my adults generally preferred to eat only Celtis laevigata (sugar hackberry) and Quercus buckleyi, as they reached senior citizen age, they chose exclusively Celtis laevigata. Please watch your animals closely while offering a variety of native plants to see which ones they prefer since their dietary preferences will change throughout their lives.



Caring for Hatching Nymphs


The greatest number of fatalities occurs at hatching. A large number of nymphs are unable to work their way out of the hard eggshell and sticky membrane.

In many cases, I was able to assist by using various tools from a dissection kit. I highly recommend that you have such tools available and be prepared to assist with the hatching process.

Tools like these may be useful in assisting with the hatching process:


Without assistance, numerous hatchlings fail:



VIDEO of failing hatching before assistance.


It's best to catch the struggling hatchling and very gently break open the egg with tweezers. Then you will need to very carefully free up the limbs from the egg membrane using the dissection tools. In many cases, you can save the nymphs.

Another very common problem is stuck eggs, which are much easier to assist with. One or both hind legs will be stuck in the egg, impairing mobility and precluding proper growth and moulting.

Newly hatched nymphs with stuck eggs:



Assisting with stuck eggs:
1. Separate the nymph you will be working on. They are very delicate at this stage and it's best to let them walk onto a paper towel and gently move them to where you can work.


2. Using tweezers, hold the egg in place in the natural position of the leg. In a few lucky instances, the nymph will be able to work his way out, but usually you will have to gently break the egg open with tweezers.

3. After the egg is broken, you will have to remove the membrane from the lower leg(s). I use needles and dissection tools for this. It can take several minutes or longer, so be patient.

4. Once you get all or most of the membrane removed, gently allow the nymph to walk up onto a plant.
This is the same nymph after being freed:


If you can't get all the membrane off, it's okay as long as the nymph can move about freely and the tarsal claws are free (for later moulting):



Egg case after successful hatching (note the missing capitulum):



Hatching and first instar are the most dangerous times for these insects. Once you get your nymphs through first instar, you should enjoy considerable success in the rest of your rearing experience. I had very few premature fatalities from second instar and beyond.



Mating

Many species of phasmids are capable of reproducing both sexually and asexually (parthenogenetically). Maginnis and Redmond (2016) examined lifetime fecundity in mated versus unmated females in laboratory conditions to determine if asexual reproduction might be "affecting long-term fitness in this species." Their study resulted in findings of 5-10% less lifetime fecundity in unmated females when compared to that of mated females based on the fact that fewer eggs are laid by unmated females. Interestingly, they found that during the first twenty days, the number of eggs laid as well as the weight of those eggs were fairly equivalent, and they note that M. denticrus in the wild might not survive predation long enough to lay eggs for more than two or three weeks. Since weight is likely a predictor of hatching success and was similar for eggs of mated and unmated females, at least in the first twenty days, the authors hypothesize that hatching rates would be similar, as well.

I was fortunate to have enough males and females for sexual reproduction.

Male Megaphasma denticrus have large rounded cerci or "claspers" that wrap around the female's abdomen during mating.



I observed that mating is prolonged and pairs often remain in copula for a few hours. The first mating of my F1 generation occurred on 05.12.2023:


Here, a gentleman caller is looking on:


Mating pair with close-up:




Laying Eggs and Egg Care


Female Megaphasma denticrus drop their eggs from up in trees to the forest floor. Maginnis et al. (2008) note that females "can lay up to three eggs per hour and thirteen per day for several months."

My Megaphasma began laying eggs approximately ten days after the first time I saw them mate.

To start your colony, you will need to separate and care for the eggs. In your large rearing cages, you will find that the females drop their eggs from their position at the top of the cage and on vegetation to the bottom of the cage. You will discover eggs mixed with frass and leaves. Every two or three days, you should change out the newspaper at the bottom of the cage and separate the eggs from the frass.

Eggs to be collected will be mixed with frass and leaves:


Keep the eggs in a separate container such that they are flat in the container on paper towels and not stacked. You will want to fine-mist them every two or three days with a very, very light misting. Ensure good air circulation to prevent mould from developing. As long as the misting is very light, this should not be a problem.

During winter, store the eggs in a mesh butterfly cage and watch them very closely. Continue light misting every two to three days. Be prepared for hatchlings quite early in late winter or early spring, and be ready to add potted plants and cuttings. I highly recommend starting and maintaining potted plants indoors through winter, including rose, your native oak and elm species, grapevine, and more.



Behaviours


These guys are quite interesting to watch. They often move about quite slowly but can also scurry with surprising speed if they need to.

One interesting thing that I noticed is that these phasmids sometimes sway or rock back and forth (as do some katydids), likely a behaviour mimicking twigs blowing in a breeze.

These insects play quite nicely together and very rarely have tiffs, certainly never a row or barney. The occasional tiff is usually over an especially tasty leaf or sometimes mild annoyance when a phasmid uses his colleague as an overpass.

Most entertaining to me was watching these guys munch. I would find myself mesmerized watching the way they move up and down a leaf, creating a trail of cute little munchie marks.

This species is very easy to handle, but special care must be taken as they are delicate. If you need to move your animals, allow them to walk onto your arm or another surface and gently nudge them into the place where you want them to be. Allowing them to walk by themselves is the safest way to move them while protecting their delicate legs and abdomen. (Never hold them by the abdomen or legs.)

Successful (and ethical) rearing of Megaphasma denticrus requires the following: very large cages without crowding, a significant amount of natural foods (their preferred native plants), and being present on the day the eggs hatch and then providing daily care throughout their lifespan. With a dedicated commitment to their comfort and well-being, you will likely find tremendous pleasure in raising and observing these oversized and utterly fascinating insects.


A happy adult very late in the season:




References

Maginnis, T. L., Cool, C. L., & Muniz, J. L. (2008). Some observations on the mating behavior of the giant walking stick, Megaphasma dentricus (Orthoptera: phasmidae). The Texas Journal of Science, 60(1), 57+. https://link.gale.com/apps/doc/A213598634/AONE?u=anon~cb649a7&sid=googleScholar&xid=04b4211f

Maginnis, T. and Redmond, C. R. (2016). Sexual vs Asexual Reproduction in a Stick Insect (Megaphasma denticrus). Biology Faculty Publications and Presentations. 42. http://pilotscholars.up.edu/bio_facpubs/42

McMonigle, O., & Clausen, P. (2002). Ghosts of the Trees (pp. 30–31). Elytra and Antenna.

Stark, B. P., & Lentz, D. L. (1986). Morphology of the Egg Capsule in Megaphasma dentricus (Phasmatodea: Heteronemiidae). Journal of the Kansas Entomological Society, 59(2), 398–401. http://www.jstor.org/stable/25084789






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