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CAPTIVE BREEDING MANUAL FOR BEETLES OF THE FAMILY SCARABAEIDAE,  SUBFAMILIES CETONIINAE (FLOWER BEETLES) AND DYNASTINAE (RHINOCEROS BEETLES)

BY:  C. CAMPBELL

(page 2)

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(b - preparation of the substrate materials)

Assuming that you have obtained the decaying wood and leaves that you need to create your beetle rearing substrate, the time has come to further break down those materials, and turn them into a soft mulch.  The leaves, being thin and brittle will be very simple to process into a finer consistency.  The wood will likely prove to be considerably more labor intensive, and I will discuss how to break up the wood first.  You'll need a standard plastic 5 gallon (19 liter) pail (sold in hardware stores), a strong flat edged shovel, and possibly even a sledgehammer for harder, more stubborn pieces of wood.  If the wood is very dry and tough, it is helpful to submerge it underwater for 24 hours or so in a large container such as a plastic trash can.  An easy way to do this is to get a large trash can with a tight fitting lid which can be locked down on the sides.  Fill it nearly to the top with the decomposed wood chunks and secure the lid.  Make a small hole in the lid that is just large enough to pass the end of a garden hose through, and then fill the can with water until it starts flowing out the hole in the lid.  Then, let it stand for a night and a day.  You'll find the wood much more pliable and easier to break up after this water saturation treatment.  After you have taken your wood out of the water the following day (assuming that you needed to use that extra step), put enough of the decayed wood chunks into the 5 gallon pail to fill it up about half way.  Then, with many strong, fast downward chops, use the shovel to chop and pulverize the wood to the point that it consists of particles that are between the size of a grain of rice and about 20 mm.  It's okay to have a number of much larger chunks than that, but you really want most of the wood to be composed of fine particles and shavings.  This can take some time and effort to do, but it is necessary.  Wear heavy work gloves to prevent damage to your hands.  This can be a rather laborious effort if you are working with decayed wood that still contains a considerable amount of harder pieces, and make sure to take frequent breaks if you feel it necessary.  Be mindful of the outdoor temperature in warm climates, and do this work in the shade.

Pulverization of decayed wood - Image  C. Campbell
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Fig. 9:  Pulverization of the decayed wood pieces into finer particles.
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Finished wood mulch - Image  C. Campbell
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Fig. 10:  The finished product - wood mulch.
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Close-up of wood mulch - Image  C. Campbell
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Fig. 11:  A close-up view of the wood mulch.

 
Just keep repeating this process of half filling the pail with wood chunks and pulverizing them with the shovel, placing the finished product into a large storage container such as a plastic trash can.  An example is shown on this page (figs. 12 & 13) of the type of trash can with lid that works very well for the storage of mulch.  As you can see, it has handles on the sides that can be used to lock the plastic lid down securely.

 
Plastic trash can for wood/leaf mulch storage - Image  C. Campbell
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Fig. 12:  A 32 gallon (121 liter) plastic trash can filled with decayed wood mulch.  Note the side handles, which lock down over the lid when in place.  Galvanized steel trash cans would probably work fine, but I am unsure of whether zinc leaching from such metal cans could act as a contaminant to the mulch.  Therefore, it is probably safest to use plastic cans.
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Ventilation holes made in trash can lid - Image  C. Campbell
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Fig. 13:  Be sure to cut or drill some large ventilation holes in your mulch storage cans to allow the mulch to breathe.  Decayed wood and leaves are practically a "living" substance, alive with millions of microorganisms such as fungi and bacteria.  If not allowed some access to outside air, the mulch can sour and become an anaerobic sludge, rendering it quite useless for creating rearing substrate.
A can of this type costs about US$10.  Several large holes should be cut or drilled in the lid as shown (fig. 13) to allow the mulch to "breathe", continuously, otherwise your mulch can develop problems with anaerobic bacteria.  These bacteria will cause a bad sulfurous smell, and can turn your mulch into an oily sludge over time.

The next paragraph concerns your wood mulch only if you did not use the water pre-soak step mentioned earlier.  When you submerged the wood, you not only softened it, but you also pretty much cleared the wood of any unwanted organisms at the same time.  If you did not use the pre-soak to soften the wood for chipping, you'll still need to soak your finished mulch for a 24 hour period to serve this purpose, in the event that it happens to contain ants or other small animals which could potentially be pests in your beetle terrariums.  After 24 hours, you should retrieve your soaked mulch and spread it out on a large sheet of plastic to dry somewhat before gathering it up and placing it in its storage can.  Do not allow it to sit in the water for more than a couple of days, otherwise it can begin to develop a sulfurous smell from bacterial build-up.  If the sun is hot, you can dry it to about the right moisture level in one day or less, but when it comes right out of the water, it will be far too wet for immediate storage.  You may want to use a rake to periodically rotate the mulch to speed up the drying process, especially if the weather is cool or there is no sun.  Do not over-dry the mulch.  It only needs to be moist enough that you can squeeze a clump of it very hard and only have it stick together rather loosely momentarily.  If you squeeze it and a lot of water freely runs out, it is still far too wet.  You will come to develop a sense of when the moisture level is right.  It should merely be moist to the touch, not soaking wet.


 
Now, here's how to process the dried leaves - the leaves need to be chipped into a finer consistency just as you did for the wood.  The simplest and most time efficient way of doing this is to use an electric or gasoline powered leaf blower (such as the electric model shown in the photo (fig. 14) which has a function for turning leaves into mulch.  This allows you to reverse the air flow from the leaf blower, so you can use it as a leaf vacuum.  When  the leaves are sucked into the machine, they are chopped up nicely by the internal blades and sent into a collection bag which can then be emptied into a large container like a trash can.  If the leaves you have collected are quite damp, you'll need to spread them out on the ground to dry them for a while, as these machines are designed to suck up dry leaves, and not ones with a lot of moisture in them.  Also, take care not to suck up any twigs or sticks, because they can jam the mulching mechanism.
Electric leaf blower/mulcher - Image  C. Campbell
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Fig. 14:  A high power leaf blower which converts into a leaf mulcher.  If you want to process large quantities of decayed leaves into mulch that is of the proper consistency for creating beetle rearing substrate, a device such as this is extremely useful.  This particular model is the Weed Eater (tm) Barracuda.  In only about 20 minutes it made 32 gallons of leaf mulch from 2 bags of compacted Oak (Quercus) leaves.

 
Of course, if you don't already have a mulching leaf blower, and don't want to spend the money on it, you can just chop up your dried, decaying leaves by some other means.  If they are brittle enough, you can get some protective work gloves and try crunching them up by hand, but if you are trying to make really large quantities of leaf mulch, a mulching leaf blower or some other sort of mechanical chipping/shredding device is really the best way to go.  If you use one of these devices, make sure to wear a protective face mask to filter the air you breathe, because they can generate quite a lot of dust when chipping the leaves.  Wear protective goggles as well, to keep the dust out of your eyes.

 
The finished leaf mulch - Image  C. Campbell
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Fig. 15:  The finished product created from decayed leaves.  These leaves have been processed through the leaf blower/mulcher shown previously, then soaked overnight, drained, and dried to just the right moisture level in the sun.
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Close-up of leaf mulch - Image  C. Campbell
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Fig. 16:  A close up view of the leaf much.
Once you've chipped all of your decayed leaves either mechanically or manually, you'll have a material that's likely to be extremely dusty and dry.  Soak the resulting mulch in water for around 24 hours in the same way as was described earlier for the wood mulch.  This will both moisturize and rid the leaf mulch of unwanted organisms.  Again, a large plastic trash can works well for this purpose.  The material created from mulching 2 large plastic trash bags full of compacted leaves will fill a 32 gallon trash can to nearly full capacity.  Put enough water into the can so as to allow for some stirring of the mulch with a shovel, but do not put so much water as to overflow it.  Once you've stirred your water saturated mulch to the extent that you can see no more dry patches, you'll have a mixture of leaves that is like a thick soup.  Let that stand for 24 hours, and the next day, remove it and spread it out to dry to the right moisture level as you did after soaking the wood mulch.  You may find that the easiest way to remove it from the soaking can is to use a strong net, which will also allow a lot of the excess water to drain out as lifted.  The moisture level should be essentially the same as for the wood mulch.  It is often helpful to first spread the mulch out on a large screen to allow excess water to gradually drain out of it.  It may take a few days to do this.  Afterward, you may still need to spread the mulch onto plastic sheets to dry in the sun further.  How you dry your mulch to the appropriate moisture level all really depends on how you are doing it, and the condition of the weather.  What you'll end up with is a very soft, moist, (but not dripping wet) material.

 
(c - combining of the substrate materials)

Now that you have created the two basic components that will form your beetle rearing substrate, the labor intensive part of your work is basically over.  The step in the process I will now describe is the final step in getting your breeding substrate ready for your beetles.  Get a large plastic bin, box, or other sturdy container to use as a mixing vat.  For a general scarab breeding substrate, mix a 50-50 ratio of wood mulch and leaf mulch, thoroughly mixing it together by hand.  That's it, you've created your substrate.  For dynastine scarabs (rhinoceros beetles) it is better to have a higher wood content, around 70% wood mulch mixed with 30% leaf mulch.

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