Male beetle showing cephalic horn
Archive for the ‘Beetles’ Category
Male beetle side view
Tuesday, January 12th, 2010
Eclosion – Chelorrhina polyphemus
Sunday, October 25th, 2009The first male Chelorrhina polyphemus has eclosed and is now dormant within the confines of the pupal cell. The remains of the pupal skin can be seen pressed against the side. This species often forms their cells against the walls of the enclosure which allows a good view of the pupation. The lower image shows a male C.polyphemus pupa nearly ready to moult – the cephalis horn is visiblas a curved process underneath the pupal skin.
Artificial pupal cell
Monday, September 21st, 2009The worst has happened - I checked on the tub today and there were tunnels everywhere. The larvae did not like my repair to its cell and has decided to abandon ship. Sources say they wont bother to build another cell so making an artificial one is the only option, and chances of a proper moult are now slim.
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Goliathus L3 in foam cell
Luckily there is a florists nearby with a ready supply of Oasis foam. Apparently there are two kinds, for wet and dry flowers. I asked for the wet kind. It is very easy to sculpt, however I dont think getting the two halves to match exactly is possible. If the larvae didnt like my fix to the crack in the original cell then I dont think it will be very impressed with this one, but it isnow the only hope. I cut round a paper egg shape to the size of what remained of the original cell, and used this template to sculpt each halve. When finished the original cell didnt quite fit into the new one, which should be about right making up for the thickness of the cell. The sides were smoothed out and cleaned of particles. I also washed the larva prior to placing it into the cell – seems like a cosy fit so I will just leave her to it. Not forgetting some elastic bands to make sure she stays in there! At least this way if it works I will be able to see the different stages of development, and will have an idea as to how the others are doing, assuming they are making similar progress.
Goliath Beetle Pupal Cell
Thursday, September 17th, 2009
Comparison between Goliathus and Pachnoda pupal cell size
Finally one of my Goliathus larvae has decided to begin the long process of metamorphosis, after reaching L3 stage in March. I was not expecting this stage to last 6 months, and was beginning to lose hope that they would pupate. I dropped the rate of feeding to one pellet every 2-3 weeks for the last three months and turned their heating off the temp was a steady 21-23C over the summer. With winter closing in I will soon turn their heating on and monitor the humidity more carefully. Although the larvae went yellowish, they never seemed to enter the ‘wandering phase’. However, yesterday I excavated the substrate in one of the tubs and to my excitement was the long awaited ‘mud-egg’ of a pupa. The size of it is enourmous, especially compared to the pupal cell of Pachnoda sp (see image).
I excavated the complete cell to check that it was intact,and overnight a crack developed in the side of the wall, which is so thin the structure seems very implausible. I could just about make out the shrivelled larva inside, and I painstakingly mended the crack by glueing large pieces of grit over the crack with a non aqueous adhesive. There is a chance this will have disturbed the larva, especially the fumes from the glue, but leaving the crack open would invite in mites and inevitably spell disaster. Fingers crossed the repair will hold, and the larva will not be too disturbed by this. I have buried the cocoon back into the substrate but left the lid slightly loose to allow more air flow.
To be on the safe side I will not disturb the other three larvae for at least three weeks, in case they are building their cells too. They were all active a few days ago so best to leave them alone. Perhaps Goliathus orientalis take longer to pupate, or it may be more likely I did not have the conditions quite right. It also might be worth noting that at least three of my Chelorrhina polyphemus are now pupating in the same room. They too belong to the Goliathini tribe so there may be some interspecific chemical communication going on. Anyone having issues convincing their Goliathus to pupate might also benefit from housing them near L3 C.polyphemus?
Newly Moulted Larva
Saturday, June 27th, 2009Below is a recently moulted L2 Megasoma elephas.
Dynastinae (Rhinoceros beetle) larvae are more bristly that Lucanid or Cetoniinae (flower beetle) larvae. The network of bluish veins under the skin are also more prominent. The orange dots are spiracles (breathing holes) which move further apart as the larvae feeds and expands. This stage in the beetle’s life cycle is purely for feeding, maximum weight gained here will allow for a larvae adult body size. Even though the larvae have to shed their skin to grow, the soft abdominal tissue can swell to several times its oroginal size. The head capsule cannot grow and so mush be shed during development – This is why newly moulted larvae apear shrivelled and squashed but with a proportionately massive head.
Dorcus titanus palawanicus L3 female
Saturday, June 27th, 2009
Dorcus titanus palawanicus (female L3)
Here the largest of my Dorcus titanus palawanicus can be seen tunnelling against the sides of the jar (850ml). The head capsule is now large so she must be in early L3 – there is a small yellow patch vivible inside the abdomen which is characteristic of female Lucanidae and is probably the developing ovaries. I will soon be transfering the larvae into 2Litre plastic sweet jar-style containers which should do for the rest of their development. They are currently living in unsupplemented decayed wood flakes, however I may prepare the new jars with a mixture of flakes and sawdust colonised with mycelium. My problems are that the pressure cooker will only take one large jar of substrate, and also that I cannot find containers over 1litre that are suitable for pressure cooking. All of the ‘oven bags’ I have tried get too britle, develop tiny holes and get contaminated.
Growing larvae
Sunday, June 21st, 2009
Above is the same larva as the previous post after 28 days. I have replaced half the substrate after two weeks when there were a lot of droppings visible. Also I have added a few moist dogfood pellets with each substrate change. Currently this larva is in a 5 litre shoe box style container with two other smaller larvae. There seems to be plenty of space for the three of them at present as long as I continue to replace the substrate at the current rate (50% hardwood mulch + 50% composted leaves). The droppings are so large I might use a sieve next time to make the process more efficient, also I am sure the pellets will make for a good plant manure.
Note the cephalic capsule has turned a much darker colour and is no longer as wide as the body.
In a compost heap near you…..
Friday, June 19th, 2009Museum Newsletter March 2009
Scarab lifecyle
How would do you feel about finding a squirming, pulsating, wrinkly, off-white maggot gluttoning its way through your compost heap?
Well, 5000 years ago such creatures were not only revered and respected, but they were worshipped as deities, denziens of Egyptian mythology and axioms in theories of the cosmos. For these revolting wrigglers have a ‘rags to riches’ life cycle, each destined to metamorphose into a brilliant shining scarab beetle. Not only do the grubs resemble mummies in general shape and colour, but they cocoon them selves into a subterranean sarcophagous-like tomb when they pupate. Here the pupa takes on such a golden cadaverous pose that this may have been the inspiration for human mummification.
Scarab beetles (family SCARABAEIDAE) are a huge family with more than 30,000 members and includes not only some of the most colourful, but contenders for the largest insects alive today. The bottom left of the above figure shows the late stage larvae of a goliath beetle (reared by the author), and to the right of it an adult specimen, one of RAMM’s impressive Coleoptera collection, of which at least 400 are scarab beetles.
The larvae feed continuously on decaying matter, moulting three times and swelling until movement is sluggish and their head only just protrudes from a collar of fat. At this point the larvae will gather droppings and leaf litter and begin building its pupal cell. Inside this earthen chamber the larvae moults once more, dropping the old skin to become the strikingly shaped pupa. Without mobile legs, the pupa can only rotate inside the cell to keep fluids moving inside whilst its organs rearrange themselves in a soup of enzymes. After a certain period of time the pupa will shed its skin and the final winged adult form is taken. The iridescent wing cases now expand against inside shape of the cell built by the larvae months previously to meticulously predetermined specifications.
Familiar scarabs include cockchafers, rose beetles and the elusive bee beetle, named for its black and orange stripes and fuzzy underbelly. An urban compost heap might provide the ideal habitat for larvae, but gardens are scattered amongst impenetrable concrete and sprawling roads. Scarabs have crawled the earth for 65 million years before the invention of pavements: next time you see a bedraggled beetle contending with tarmac give it a break and fling it into a flowerbed – or Khepri, the solar god of resurrection will have your guts for garters!
Chelorrhina polyphemus
Sunday, May 24th, 2009This is a recently moulted 2nd instar larva:
