Amateurs who breed stag beetles have much interest on how to raise bigger adult insects. How to raise bigger adult insects means how to raise bigger larva because the size of the adult insect is determined by the size of larva and never changes once he/she becomes adult. As you can imagine, this is due to exoskeleton of stag beetles.

Many trials have been made to raise bigger larva. As I posted on “How to breed larva“, breeding using flake wood or a wood were major method at its early stage. However, from late 1990s “mycelium bottle” has been recognized as the most effective method to raise stag beetles. The mycelium bottle is only effective for limited stag beetle species, but it spread fast in Japan because the bottle was highly effective to raise Dorcus hopei binodulosus, which has been the most famous stag beetle species in Japan.

Photo: Mycelium bottles in a stag beetle shop

◆ What is the mycelium bottle?

A mycelium bottle is a product filled with flake of hardwood (typically sawtooth oak) in which mycelia are spread. The mycelium bottle was firstly developed in the field of fungiculture and applied to the stag beetle breeding in 1990s. The mycelium bottle is produced by following procedure. 1. add water and additives to the flake of the hardwood. 2. sterilize it by heating. 3. inoculate and grow fungi (Pleurotus cystidiosus or Coriolus versicolor etc.) in it.

◆Birth of the mycelium bottle in stag beetle breeding area

Amateurs noticed that Dorcus hopei binodulosus in the wild grows bigger in woods decayed by Coriolus versicolor. In 1992, Mr. Inoue, who was working for a mushroom growing company posted his thoughts on a monthly journal of entomology how Coriolus versicolor may help Dorcus hopei binodulosus.to grow (Ref.1). In short, Coriolus versicolor degrades lignin, which is one of the components of wood, and convert it into nutrition available for the stag beetles. It was natural that this thought was applied to the breeding technology. I could not find the evidence, but Mr.Inoue’s company was said to be the first one that provided commercial mycelium bottle in 1992.

◆Establishment of method how to utilize the mycelium bottle

Although multiple companies started selling mycelium bottles, amateurs faced higher death rate of larva in the mycelium bottle. Dr.Morita was the person who tackled into the problem and shared his stable and effective method to amateurs. He started his study how to raise Dorcus hopei binodulosus in the mycelium bottle (he used Pleurotus cystidiosus) stably and effectively. He collected data from over a hundred of larvas each year and posted his data on a monthly journal of entomology in 1997 (Ref.2). He regularly shared his method obtained from his study and helped other amateurs to breed bigger Dorcus hopei binodulosus.

◆What did the mycelium bottle bring

The mycelium bottle is recognized as stable and reliable method to raise big Dorcus hopei binodulosus. The development was certainly a technical breakthrough. The largest group of the stag beetle have been constantly raised by the mycelium bottle. Also it made breeding big Dorcus hopei binodulosus easier and lowered the price of the stag beetle. Even children can breed big Dorcus hopei binodulosus using it now. Additionally, the contribution is not limited to Dorcus hopei binodulosus. For certain stag beetle species, the mycelium bottle is the only method to breed so far.

Amateurs will continue to seek for even more effective breeding method. How do you think what would be the next to the mycelium bottle?

1. A monthly journal of entomology, Aug. 1992

2. A monthly journal of entomology, Jun. 1997