Rhinoceros beetles, part of the Scarab family, are renowned for their distinct appearance and impressive size. They exhibit rounded dorsal surfaces and many species within this group possess prominent horns on their heads, which give these beetles their name. One notable example is Xyloryctes jamaicensis, a large reddish-brown beetle that typically measures 25-28 mm in length source.
These fascinating insects exhibit a life cycle that undergoes complete metamorphosis, passing through four distinct stages: egg, larva, pupa, and adult source. This article will delve into the intriguing life cycle of rhinoceros beetles, focusing on each metamorphic stage, their unique behaviors, and the impact they have on their surrounding ecosystems.
Life Cycle Overview
Stages of Development
The life cycle of a rhinoceros beetle consists of several stages, including:
These stages make up a complete metamorphosis process.
Duration of Each Stage
Below is a brief overview of the duration of each stage:
|7 to 10 days
|11 to 49 days, depending on the instar
|3 weeks(teneral) + 1 week (feeding) + 2 weeks(dispersal, mating)
As observed, the duration of each stage may vary. For instance, the larval stage lasts depending on the instar (there are 3 instars). Each stage plays a vital role in the rhinoceros beetle’s life cycle development.
Eggs and Larval Stage
Egg Laying and Incubation
Rhinoceros beetles mate during the mating season. Female beetles lay their eggs in decomposing matter, like tree bark or compost. Incubation typically lasts around 7-10 days. Examples of suitable breeding grounds include:
- Rotting logs
- Compost heaps
- Mulch piles
During this time, the eggs are left undisturbed to develop.
After incubation, larval stage begins. The larvae are called grubs, and they are usually white and C-shaped. Larval development goes through several life stages called instars. Key features of larvae include:
- Creamy-white body color
- C-shaped appearance
- Voracious appetite
Larvae need proper nutrition to support their development. They primarily feed on decomposing plant matter, which provides them with essential nutrients.
Through their instar stages, rhinoceros beetle larvae undergo a process called molting. Molting allows the larvae to shed their exoskeleton and grow. This process occurs several times as the larvae develop. During each molt, the larva grows in size and moves closer to the next stage of its lifecycle.
Here is a comparison table of different larval instar stages:
In summary, the eggs and larval stage of rhinoceros beetles involve egg laying, incubation, larval development, and molting. Understanding these stages can help in better knowledge of their growth and development process.
Pupal Stage and Metamorphosis
Duration of Pupal Stage
The pupal stage of the rhinoceros beetle typically lasts for a few weeks, depending on factors like temperature, humidity, and species. For instance, some species may take as little as 3 weeks, while others may take up to 8 weeks1.
Physical Changes During Metamorphosis
During metamorphosis, the beetle undergoes significant physical changes within the pupa, completely transforming its body structure. Examples of such changes include:
- Development of wings
- Formation of a hardened exoskeleton
- Growth of horn-like structures (in males)
The pupa is a non-feeding, immobile stage in which internal reorganization takes place. It remains hidden in leaf litter and soil, providing protection from predators.
Leaf litter provides a suitable environment for the pupa, as it offers a moist, dark, and insulated habitat, ensuring optimal temperatures and humidity levels for development.
Comparison of Pupal Stage in Rhinoceros Beetle and Another Insect:
|Varies (e.g., 10-14 days in butterflies)
|Leaf litter or soil
|Varies (e.g., chrysalis attached to a plant in butterflies)
|Holometabolous (complete metamorphosis)
|Varies (e.g., butterflies also have complete metamorphosis)
Adult Rhinoceros Beetles
- Eastern Hercules Beetle: One of the largest insects in the United States, males can reach 7 inches in length, with horns usually about 1/3 of the body length.
- Coconut Rhinoceros Beetle: Stout, brownish-black in color, both males and females have a distinct horn on their heads. Length varies between 1.2-2.4 inches.
- American Rhinoceros Beetle: Both sexes are large, reddish-brown, and typically 25-28 mm long (1-1⅛ in).
Males often use their horns to:
- Fight with other males
- Compete for mating opportunities
- Eastern Hercules Beetle: Commonly found in deciduous forests of Eastern United States.
- Coconut Rhinoceros Beetle: Occurs in tropical regions around the world, often causing damage to economically important wild and plantation palms.
- American Rhinoceros Beetle: Prefers wooded areas in Eastern North America.
|Eastern Hercules Beetle
|Up to 7 inches
|Deciduous forests (Eastern US)
|Tropical regions (worldwide)
|25-28 mm (1-1⅛ in)
|Wooded areas (Eastern North America)
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – A Herd of Rhinoceros Beetles!!!!
Budding entomogist with a question
My 9 year old daughter, who happens to be a budding entomologist, discovered these dead beetles at her grandfathers house yesterday and she can not identify them. She searched all her bug books and could not find anything that looked like it. She has been collecting bugs for the past 3 years, and this is the first time she has been stumped!! If you could lend a hand, she would be very happy! P.S. She LOVES your website! I can see her being on here for a few hours each night!
Letters like yours are truly the reason we began this site. Your daughter has assembled quite a herd of Rhinoceros Beetles, Xyloryctes species. Males have the prominent horns. Here is a link to BugGuide, a truly magnificent identification site which just might double the time your daughter spends online. We also love your photo so much we printed it twice the size we normally post. By the way, we are probably going to produce a calendar for 2006 and would love to use your image and letter.
Letter 2 – Atlas Beetle of Borneo
These bugs were photographed in my parents back garden on the island of Borneo, Indonesia. Any idea what they are?
The magnificent beetle is one of the Hercules Beetles in the subfamily Dynastinae. They are also known as Rhinoceros Beetles. Eric Eaton just provided this correction: ” The Borneo “hercules beetle” is actually an “atlas beetle” in the genus Chalcosoma. The specimen is a male, and the genus is in the hercules subfamily Dynastinae.”
Letter 3 – Australian Rhinoceros Beetles
Rhinoceros beetles from Australia
this is Chris… you posted a photo of my daughter’s phasmid last year, with a link back to my site (thank you 🙂 I have just returned from south-east Queensland, Australia (to Sydney, where I live) and collected a plethora of fantastic bug pics. However, I thought I might just share a few because I know time is short when you’re maintaining a large site! Follow the link to my article about two species of rhinoceros beetle I found.
One is considered rare (Haploscapanes australicus?), the other quite common (Xylotrupes gideon). The common one is enormous and the first photo on the site shows it sitting on my hand (for scale).
Thanks for sending us your photos and providing an indentification. We have linked back you your site where people can find more information than we are posting. We have posted the two photos of the common Xylotrupes gideon above and the single photo of the rare Haploscapanes australicus below.
Letter 4 – Black Hercules Beetle
Name this beetle
We found a remarkable beetle in our back yard and was hoping that you could help us identify exactly what type it is. We believe it to be some type of Rhinoceros Beetle. It is 2.5 inches in length and over an inch wide. We have taken several pictures and have attached two to this email. We found the beetle in our Maryland yard already dead. He had some tent worm silk covering his head, which may have contributed to his demise.
Bugguide states: “Some females are nearly black”, but it says nothing about dark coloration in the male Hercules Beetle, Dynastes tityus. We have gotten written reports of these beetles changing colors (see below).
Amazing Technicolored Dynastes tityus
I know, I know, you are swarmed with questions. But I just can’t find any answers or others who want to answer! I found a Dynastes titus. I identified it with the help of your site, thank you! I then read on other www’s how they are easy to keep as pets. I followed some pet advice, and he has an aquarium set up that I think most Rhino bugs would give their bottom horn for. However, today, he was not looking his usual coloring, which is a creamy olive with black spots. He was COMPLETLY black. Still very lively, and eating a piece of fresh pineapple soaked in maple syrup. I took him outside and put him on the ground, and he changed back to creamy olive with black spots right in front of my eyes! I had no idea that insects were capable of this sort of transformation. I made a makeshift box for him, and placed it outside for a little while. When I checked on him again, he was half under a bit of bark, and he was 1/2 black, under the bark, and 1/2 olive-y in the sun. My question is, Does he need to be the olive color? Is it a sign of some kind of deficiency? I’ve had him for three weeks, and he’s not done this before now. I am unable to find anything on the Internet about this, even on the web pages describing how to keep him as a pet.
P.S. No pictures, because my camera is in the shop. If you are not too swarmed, I will send you some as soon as I get it back. He (no name yet) is beautiful.
We know that these beetles are sometimes a mahogony color, but we are not sure what causes the changes. Our best advice is to inquire from sites that advocate raising these beetles. We don’t think the color change is indicative of poor health.
Thank you. The beetle died this morning. He still changes color even though he is no more. I think it is a temp thing.
Update from Eric Eaton: “The key here is that it was dead. Large beetles are well known for turning black after death due to becoming saturated with grease as their fatty bodies decompose. Not a pretty answer, I know, but the correct explanation:-) I have some specimens of my own to which this has happened, sometimes on only the half of the insect through which the pin passes. I can’t comment on the color-changing phenomenon the one person documents. You should contact Brett Ratcliffe at Scarab Central, the entomology department at the U. of Nebraska, Lincoln. Eric”
Update (08/23/2006) Technicolored Dynastes tityus
I just read the “Amazing Technicolored Dynastes tityus” and had something to add. Both D. tityus and D. granti, and apparently the other species in the genus, will change color due to moisture fluctuations. Whenever I remove an adult from it’s substrate it will appear very dark but will return to it’s normal coloration after a minute or so. I imagine this would be a nice camouflaging technique because a bright green beetle walking through moist leaf litter would stand out. This change is normal and is not due to temperature or any nutritional deficiencies. I have seen preserved specimens retain this darker coloration regardless of the humidity levels but Elizabeth’s beetle was changing back, which makes me think it was humidity. I found two links that mention this subject: http://bugguide.net/node/view/11562 and
Letter 5 – Broken Paypal Button fixed and Coconut Rhino Beetle found on Oahu
Aloha Daniel & crew –
In early January I donated to your page via the Paypal button.
It bounced back to me as Paypal doesn’t seem to have that email address affiliated with your page.
When this rejection occurred, I wrote you a note using the submission section of your site and it seems the email system just bounced it back.
So here I am using the two email addresses I’ve had for you.
May you get the donation button fixed. And let us know when it is working.
Here’s a link to a story about the discovery of the Coconut rhino beetle found on Oahu.
And another one –
Take care –
It is so kind of you to let us know about this problem, which probably explains why revenue is way, way down. We are copying Daniel the web master to have him check on the problem with the Paypal button.
Update from our webmaster
Hello. I fixed the bad address, probably shortly after you noticed the problem. Feel free to try it again! Unfortunately, people don’t donate very often. I wish I knew why!
Most welcome & many thanks to you both for your responses.
Saw my post on the site this morning. Will donate next month. 😉
May your words and the post today help things along in the donation department.