Breeding beetles

So how does it work?

The breeding and rearing of beetles in captivity entails alot of care and an equal portion of patience. Breeding beetles is not something fast – at all.

Flower beetles

I specialize in mainly African and palearctic flower beetles (cetonidae) which are usually very bright and colorful beetles, come in all possible sizes, and most of them take anywhere between 8 to 14 months to complete metamorphosis from egg to beetle.
Depending on the species and the degree of difficulty more time might be needed to complete metamorphosis, (such as for example Goliathus that needs 4 months in cocoon to complete metamorphosis and another 3 – 4 months of sleepy time in cocoon as well).

Keep in mind there are many stages to complete, and for most species of flower beetle the time spent as larva outweighs the life span of an adult beetle by 3 or 4 times!

Life cycle stages (applies to cetonidae, lucanidae and dynastinae):
egg –> larval instar stages L1, L2, & L3 –> making a pupal cell (basically a cocoon made of dirt) –> metamorphosis: larva – pupa – eclosion – beetle –> the active beetle emerges from the pupal cell.
When the beetle emerges from its cocoon it will start looking for food and start searching for a mate to repeat the cycle.
In general, the larvae eat substrate and white rotten wood and the adults eat overripe fruit, nectar, tree sap, and some scavenged protein.

rules of thumb for breeding flower beetles:

  • The substrate height should be at least 3x the length of the female for her to lay eggs.
  • The bottom 1/3 of the box should be firmly pressed substrate. This is called a mat and it’s where the female will lay her eggs. The mat may consist of regular oak/beech substrate, a powerfood such as flake soil to give young developing larvae a boost, or even inedible substrate such as peat moss to facilitate the female’s oviposition – this depends on what works best for that particular species.
  • a 12 hour light schedule (minimum). these are diurnal beetles and will be active during the day. Not enough daylight may result in a very low number of eggs. I advise installing a led spot in or on top of their enclosure. They will often bask, eat and mate right under the light source.

Stag beetles

In the second semester of 2019 I took on a new challenge and decided to take my first baby steps in the breeding and rearing of Lucanidae (stag beetles). Something completely different, but it would make an interesting experience no doubt. What seemed so appealing about stags beside the impressive mandibles was the large array in sizes and colors (much like flower beetles) that these beetles would display depending on the species, but even more so the life span as an adult. Adult male stag beetles can reach a lifespan of 8 months to a year or more!

I started my journey with Prosopocoilus giraffa keisukei and Phallacrognathus muelleri.

Things i discovered:

  • 24°C is the sweet spot for the adults to mate and the female to lay eggs. At colder temperatures they seem much less willing and sometimes even hostile towards each other.
  • The mating box can be different from the rearing box. Often a smaller box with food and less substrate for the female to hide herself is more efficient to establish successful mating. Always introduce the female to the male’s box. The male guards the food and waits for the opportunity for a female to appear and eat.
  • The larvae can be reared at varying temperatures from 20°C to 26°C. Larvae are reared in individual containers as of L2/L3 with a high protein flake soil very very firmly pressed together. If the substrate becomes too loose the larvae will often wander at the top of the container. The alternative is using kinshi (a container with mycelium used for cultivating mushrooms). I like to use 1 to 2L round bucket shaped container per individual.
  • In 2021 I decided to end my stag adventure simply by not allowing my adults to breed. As much as I love the appearance and longevity of stag beetles, I noticed they required more time and different care than cetonidae. And with the amount of flower beetles I currently have, the task was inconvenient to combine.

Rhinoceros beetles

Another group of beetles is dynastinae (rhinoceros beetles). A group which has always seemed dull and uninteresting to me. Sure they have large horns, but these are all darkly colored beetles with a nocturnal schedule. Meaning they are mostly active while we sleep, which made them less enjoyable and watchable – to me at least.
Until I was gifted an elephant beetle male by a friend in September 2019. Slightly impressed by the colossal animal, I started looking if I could find and purchase a female for him somewhere. I got my hands on an unrelated female from a good breeder in Spain and voila – my CBF1 generation could commence.

The couple turned active in November 2019 and started mating and laying eggs almost immediately. The couple passed away in February 2020, but had left me with offspring. The first part of their colossal offspring emerged in September 2021 with males measuring well over 11 cm.

Things I discovered and learned:

  • a new rearing box should be provided to the female every month
  • After the couple’s passing (feb 2020) to my great surprise their rearing box only showed eggs, not a single larva. I was absolutely baffled as I had already checked the box in November 2019 to make sure she liked what i had prepared for her and in that first week i could already see the first eggs! It appeared I had made a dynastes beginner’s mistake by not placing the female in a new breeding box each month to maximize my return. After talking to more experienced rhinoceros breeders, it was a known fact that these females lay a crazy amount of eggs, but that they also destroy many of the eggs while digging in the box. So there I was, in February, with a 3 month old breeding box that only contained eggs :’). Come March I finally saw the eggs had turned into larvae in the box and I was super relieved.
  • larvae can be reared at varying temperature from 21°C to 28°C

I personally like to rear at high temperature with a high quality substrate, so I kept them at a temperature range of 23°C (winter) to 28°C (exceptional summer peak). And used a substrate mix of 50/50 rich black soil and cetonid compost mix.

Bi-monthly weighing showed rapid growth with male larvae already reaching 100 to 118 grams in September 2020. Keep in mind these larvae were still eggs in February 2020.