22: A small 2.5 pint (1.18 liter) pressure sprayer which is useful
for regulating the moisture level of terrarium substrate. Most models
have an adjustable nozzle which will allow you to find a misting setting
which works well for your particular situation.
23: Rearing substrate which is of just the right moisture level for
rearing scarab beetles. The substrate should be carefully monitored
for signs of desiccation on a regular basis, and should be kept moist at
all times through all life stages.
24: A close-up view of the rearing substrate. Be careful not
over moisten your substrate, as one which is too wet can be just as inappropriate
as one which is too dry.
|(c - temperature
for the breeding / rearing terraria)
Most tropical scarab
species do best at a temperature of between 75-85 degrees Fahrenheit (24-29.5
degrees Celsius). Keeping them too cold will either make them sluggish
or even kill them, because their metabolic processes won't work properly
at lower temperatures. They are exothermic (cold-blooded) animals,
and their body temperature stays at approximately the same temperature
as their surrounding environment. For species from cooler parts of
the world such as North America, the temperature can be allowed to drop
lower than 75 degrees Fahrenheit at times, and in fact some species which
come from high elevation forests in cooler climates need a seasonal variation
in temperature to properly complete their life cycle.
(d - lighting)
Having an overhead
fluorescent tube light for your breeding terrarium can be helpful in encouraging
normal breeding activity in some varieties of scarabs, most notably, the
cetoniines (flower beetles), which are active by day. Direct lighting
is not considered to be very important for dynastine scarabs (rhinoceros
beetles) which are mainly active at night. Also, it is not necessary
to light terraria which are for growing larvae only, as the larvae live
buried in the substrate, and thus lighting is of no significance to them.
(e - humidity)
The substrate should
be kept moist, but certainly not soaking. A pressure sprayer is useful
for maintaining the balance of moisture in your breeding / rearing terraria.
Various sizes of these devices can be purchased in the gardening section
of most hardware or department stores. If you have many terraria
to spray regularly, get a 2 gallon (7.60 liter) model. If you have
only a few terraria, a smaller size sprayer such as the one shown in the
photo (fig. 22) will suffice. Whatever you use for spraying water
in your terraria, make sure that the vessel has not ever been previously
used for spraying insecticide or any other chemical which may have left
residues that could prove harmful to your beetles. The substrate
should be somewhat damp to the touch (see figs. 23 & 24), but if you
can squeeze a clump of it in your fist and get water to run out of it very
freely, it is probably too wet.
|In general, spray
the surface of your substrate when it starts to look rather dry.
A hard crust may form on the surface which can be rather misleading.
This crust can conceal a very most layer just beneath the surface, so always
break this crust first to make sure that you aren't actually moistening
a substrate that is already moist.
(f - feeding (adult
Most cetoniine and
dynastine scarabs will happily accept soft fruits such as banana in captivity.
A few species like pear or apple.
|Give them a fresh,
adequately sized slice of such fruit each day if you can. Every 48
hours will suffice, but feeding them a fresh piece each day is recommended
because the beetles tend to make a pulpy mess of the fruit, and it starts
spoiling VERY fast in the high humidity of the breeding terrarium.
To supplement the beetles with any protein requirements they may have,
you can sprinkle a quantity of ordinary flake fish food on the surface
of the banana slice or other fruit. Also, some species will eat apple
sauce, again with fish flake fish food mixed in for nutritional enrichment.
This can be a much less expensive alternative to fresh fruit if economy
is an issue. Slight misting of the terrarium and beetles occasionally
will supply moisture needs for both the insects and the substrate.
Just mist the terrarium if the environment starts to look a bit dry.
(g - first appearance
of eggs and young larvae)
If you start out
working with adult beetles as opposed to larvae, and have prepared your
substrate and breeding terrarium as I have indicated, you should start
seeing eggs or young larvae within a short time. Usually, you can
get your beetles to deposit eggs within just a few weeks of having introduced
them to the terrarium. Mating (see fig 25) may be observed
almost immediately, but the females may take some time before actually
starting to lay eggs. A few weeks or even a few months are sometimes
needed before egg laying, or "oviposition" starts taking place.
25: A mating pair of C. caucasus. Actual mating in this
and most other species of scarabs can take between 10-20 minutes.
Mating beetles are often rather difficult to disturb, and generally will
take little notice of movement in and around their terrarium. Using
their highly sensitive lamellate antennae, males locate females by the
pheromones which they emit. Like most other arthropods, scarabs utilize
a specialized structure called a "spermatophore" for the transfer of spermatozoa.
This structure is simply a sealed packet of spermatozoa which has a tough
yet flexible outer layer. Male dynastines sometimes deposit spermatophores
on the substrate surface as they produce them, especially if they do not
have access to mates. After mating, the female may not necessarily
deposit her eggs immediately. Time is needed for her eggs to become
fertile. Dynastine species such as Chalcosoma burrow deep
into the substrate to oviposit, whereas many cetoniines simply deposit
their eggs nearer to the surface.
|The female beetles
may burrow deep into the substrate to lay eggs, or may deposit them near
the surface, depending on species. Large types, such as those in
the subfamily dynastinae, nearly always oviposit their eggs very near the
bottom of the substrate. As always, the substrate surface will need
to be misted occasionally to prevent the lower layers from drying out.
The amount of misting will vary depending on the humidity of the air in
the room, but usually it will need to be done every two or three days if
the humidity is low. Avoid over watering, otherwise the lower substrate
can become rather saturated, even when the surface appears quite dry.
Over watering can prove fatal to the eggs. Continue to make sure
that the adult beetles are given fruit as needed, at a frequency of at
least every two days, or daily if possible.
26: A newly hatched C. caucasus larva and un-hatched egg shown
beside a US 25 cent piece. Larvae this young are extremely susceptible
to damage, and should not be handled directly. If moving sensitive
larvae or eggs such as these is for some reason necessary, do so by scooping
up the substrate upon which they are resting, rather than attempting to
pick up the larva or egg itself. Also use extreme care when covering
them back over with substrate. The larva shown is called the "1st
instar", and through the course of its development, it will increase in
size and weight by hundreds of times.
|A few weeks after
introducing the beetles to the substrate, you can very carefully dig down
into the substrate and check for the presence of eggs or young larvae.
Cetoniine scarabs tend to deposit eggs in the upper and middle layers of
substrate, although this is not always the case with some of the
larger species. Because the dynastines oviposit near the bottom,
it is often best to not disturb this area for a considerable time, 6 -8
weeks in some cases. The eggs are quite delicate, and often susceptible
to rupture if handled. It is important to move the substrate around
quite gently, as the eggs and young larvae are easily injured. At
this point in time, the larvae would likely still be quite small if present
at all. Again, keep in mind that it may take as long as 6-8 weeks
before any larvae appear, as the oviposition +egg incubation period varies
depending on the species. Bear in mind also that the beetles may
not necessarily begin laying eggs immediately after mating. The eggs
of course vary in size depending upon species, up to 1/4 of an inch (6.35
mm) in the case of large rhinoceros beetles such as Chalcosoma,
and are generally light in color. Continue feeding and maintaining
the adult beetles as always.