Scarab beetles -
The captive breeding
of scarab beetles of the families cetoniinae and dynastinae will be discussed
in this online manual. There is a general technique for rearing such
beetles which involves creation of a rearing substrate consisting of two
basic materials: wood mulch and leaf mulch. The process for
creating these two substrate components will be described early on in the
manual. The manual is divided into two sections. Section 1
concerns mainly the procurement and preparation of the materials you will
use to create your rearing substrate, and section 2 deals with the actual
biology and life cycle of the beetles themselves. The mulch ratios
and extra additives used in the final substrate mixture will vary depending
upon the species you wish to rear, and all beetle hobbyists have their
own personal variations and techniques of using it. I would like
to point out that the rearing of scarab beetles is by no means an easy
thing to teach someone, and it is actually a skill which must be learned
by personal experience. To become a real master of scarab beetle
propagation, one must often work at it for many years as one would for
a hobby such as exotic plant culture. In time, you will develop an
innate sense about things such as substrate quality, and will be able to
determine its precise moisture level and consistency just by touching,
smelling, and looking at it. The sequential instructions presented
in this manual however, will give you a good head start about what to do.
(note: If you
are seeking information specifically about Goliathus, please refer
to the Goliathus
manual for breeding/rearing info on such. Also, you can read
an excellent article by beetle hobbyist Yasuhiko Kasahara about the captive
breeding of Dynastes hercules here.)
|Section 1 -
Substrate collection and preparation:
Before you even obtain
some pairs of adult scarabs for breeding, it is always a good idea to at
least have the materials prepared that will be used to create the rearing
substrate. The materials used to rear beetles of the subfamilies
cetoniinae and dynastinae are heavily decomposed deciduous hardwoods and
old leaf litter that has aged to the point that it has become a bit soft
and moldy. When found in nature, these two materials are very seldom
of the proper consistency for ideal use as a rearing substrate for captive
beetles, and they usually must be broken down further. So, the first
section of this manual will be concerned with explaining the methods by
which one actually prepares these two materials, and uses them to create
the rearing substrate which is the very foundation of captive scarab breeding.
(a - collection
of the substrate materials)
Obviously, the first
thing you need to do is locate some sources of decayed wood and leaves.
If you have access to some deciduous hardwood forest or woodland (see
figures 1 & 2 at right), that will certainly be one of the best
places to look for what you need.
1 & 2: Shown above are some examples of the sort of deciduous
hardwood forest that are excellent places to find a ready supply of very
old, decayed logs and leaves. From these materials you can create
the mulches which will form the basic components of your scarab beetle
3: Here is an extremely old Oak (Quercus) log which is in the advanced
state of decomposition ideal for creating wood mulch for beetles.
The wood has become yellow-white with age, is very brittle, and is easily
crushed with bare hands.
4: In this instance, the decayed wood is a stump rather than a fallen
log. Note that the color of the wood is of a rusty brown hue.
Often, you will be able to determine if a log or stump is at the proper
state of decay just by looking at it. This stump is infiltrated by
the burrows of many beetle larvae and other insects, and the mushrooms
of wood fungi are present on the bark.
|Note: If you
live in a part of the world where venomous snakes and spiders are common,
use caution when exploring a wooded area.
For the wood, what
you'll be looking for are rotten, decomposing logs and stumps of deciduous
hardwood trees. These are non-coniferous trees which shed their leaves
each year, and have wood which is quite hard when in the living state,
hence their name. A large hardwood log lying on the forest floor
can take upwards of 10-15 years to become aged to the point that it will
make an attractive food for scarab beetle larvae. Wood that is fresh
is completely useless. Even an old hardwood log can be difficult
to break into pieces of a manageable size to transport home, so it's a
good idea to bring some strong tools to break up logs. Fungal action
is the decomposing agent that makes these logs suitable as a component
for rearing substrate. When the spore (microscopic seed) of a species
of wood-eating fungus lands on a log which is of proper age and moisture
content, it starts sending out tiny roots called mycelia. Over many
years, these mycelia spread and gradually party digest the hard cellulose
of which the log is made. In time, the log is transformed from a
very solid wood to one that is very soft and crumbly. In addition
to the fungus, there are other living things which help get the log into
a condition appropriate for your use. Ants, termites, and the larvae
of many beetles and other invertebrates all take up residence inside logs
and dead stumps once fungal transformation has begun, and further aid in
breaking down the wood into a suitable, crumbling consistency. One
of the very best varieties of decomposing wood and leaves to use is that
of Oak trees (Quercus spp.). Also, that from Beech (Fagus
spp.) is very suitable.
5 & 6: Some further examples of well decayed wood that is suitable
to be made into rearing mulch. If a log readily shatters to the core
when given a hard kick, it's definitely at the right level of decomposition
to serve your purpose. For logs and stumps that are well decayed
on the inside yet retain a hard outer layer of wood, a sledgehammer or
pickax will prove useful in breaking the wood up into more manageable pieces.
|In general, decomposing
material from all species of deciduous hardwood trees can be used, but
one should generally avoid the use of coniferous (needle-leafed) trees
such as Pine (Pinus) and Cypress (Cupressus). The reason
is because the wood of these trees contain resin and oils which are toxic
to scarab beetle larvae. Thus, the many commercially available forest
products such as pine bark mulch and cypress wood mulch are quite useless
to the beetle hobby. If you live in an area of very old growth coniferous
forest, and find a log which has obviously been decomposing for an extremely
long time and has become exceptionally soft and crumbling, it can be used
so long as you cannot detect any resin smell upon close examination.
If it has a strong fungal smell when moistened, then you can be reasonably
sure that it has reached a stage of decomposition that would make it suitable
for scarab beetle larvae. The main concern with coniferous wood lies
with the presence of resin. Very old and rotten conifer logs and
stumps lack this compound, as it gradually evaporates out of the wood during
the decomposition process.
7: A huge and very old Cottonwood (Populus) log whose degenerative
state is not especially apparent from an external point of view.
However, there is a lot going on inside it, as is evidenced by the numerous
mushrooms of "shelf" fungi which have sprouted from its sides. Shelf
fungi are one of the most commonly encountered varieties of wood-eating
fungi in the woodlands of North America. Given time for a bit more
decay, a decomposing log of this size will yield a vast supply of rotted
wood for use in beetle breeding.
|It does take many
years for this to occur, however, so only use conifer wood which you are
quite sure is extremely old and decomposed. Some types of conifer
wood, such as Cedar (Cedrus) never really become suitable for use,
as their wood is so dense and strong that it can withstand the forces of
decay for many decades, remaining completely hard and intact.
If you can get access
to fine shavings or sawdust from hardwood trees however, that would be
suitable, but it would still be fresh and un-decomposed, and some alteration
would be necessary using commercially available fungal cultures.
Making your own decomposed wood using fungi is a process complex enough
to warrant its own section in this manual, and so it will be discussed
at some point in the future after I have gained experience with it.
For now, I will continue to describe the means by which one makes rearing
substrate by simply using materials gathered from nature itself.
8: A typical compost pile, consisting primarily of layers of leaves,
grass clippings, and various other plant materials. A compost pile
can be a convenient way of maintaining a ready supply of decayed leaves
throughout the year. The feeding activity of bacteria and many other
small organisms all help to party break down the leaves and get them into
a condition suitable for creating the decayed leaf mulch which is one of
the two main components of scarab rearing substrate. An added bonus
of a compost pile is that by creating such an accumulation of plant material,
you can often attract the native scarab beetles which you may find interesting
to captive rear.
|As for the decomposing
leaves, I think you'll find this a much easier material to find and collect.
Deciduous hardwood trees such as Oak (Quercus), Beech (Fagus),
Elm (Ulmus), Maple (Acer) and many others are all suitable.
It is best to use leaves from species which have rather large leaves, because
this will end up amounting to a greater quantity of the leaf mulch which
will be created from them. It is possible to use rather freshly fallen
leaves once they have been on the ground for several months, but if you
can get leaves that have been "composting" for a couple of years and have
obvious signs of decay, that will be even better. To quickly gather
old leaves for transport, I just rake them into large piles and then stuff
them into ordinary plastic garbage bags, compressing them periodically.
To always have a ready supply of decomposing leaves year-round, you might
want to consider creating a special compost pile for leaves only.
A small space enclosed with fencing or wooden panels will work well for
this purpose. All you need to do is keep the leaves in a somewhat
sheltered area to prevent them from being blown away in the wind.
See the example in the photo at left (fig. 8).