Breeding Cetonia aurata

N

naftaliin

L1
I want to start Cetonia aurata indoor population. These flower beetles are common here and I collected 35 larvae from an old sawdust pile in the autumn. Most of them pupated and I'm hoping to get them mating. I have 26 imagos (15 female and 11 male). I been feedeng them apple and keeping in the dark between 23 and 25 degrees C. I've read that they are active during daytime. So to breed them I need to put them in a well lit box? But I'm not sure how big of a box with substrate (decaying wood) I need to use. Some say that beetles lay less eggs when there is not enough room. I kept larvae in 750 ml boxes. Is that going to be enough for breeding? How many eggs does one isect lay? Is there any chance that larvae might show signs of cannibalism when it is too crowded? Anybody have specific experience with that insect? I'm also not sure how much time I have left because first imagos emerged already a month ago.

Greetings form Estonia!

 
I have reared Cetonia aurata in the UK. Larvae pupate in late summer and early autum and in the wild spend the next winter underground in their pupal cells, emerging in April and May. In captivity, I have had adults emerge in late summer. Despite lots of food and lots of mating, none of these laid any eggs and by the end of September / early October were spending most of their time underground at the bottom of the tank. I placed the tank in an unheated brick shed for the winter and brought it back inside in April. At this point the beetles emerged from hibernation and happily laid lots of eggs - I had over 350 larvae from 16 females in the end. It would appear that the adults do need to hibernate / pass through a period of cold before they will begin to lay eggs

I kept my adults in plastic tanks / old aquaria on my windowsill in full sunshine - they are much more active in sunshine or a warm, well lit tank. Dark tanks are no good. They will lay happily in a mix of leaf litter and old wood, though the wood should be finely chopped - large lumps are no good. Adults will eat fruit like banana or apple and are also very keen on pollen substitutes made from mixing brewers yeast and honey. For the number of adults you have a couple of large plastic aquaria 30 x 20 x 20 cm should be ok - fill them with 15cm depth of substrate. The larvae are happy to be reared together, i did not see any sings of cannibalism.

 
Very interesting. Not sure about the overwintering in pupal cells.. just found larvae last week (7th of january) in another sawdust pile and no pupal cells.

Mine emerged after being about 1.5 months in pupal cells without a cold period. And some of them indeed burrow to the bottom like you described. Had them separetly till now. Paired some of them together today. Perhaps I have to create some cold period myself after they mate. What are the temperatures in your area during wintertime?

 
I have some past experience with Cetonia aurtata too (cute little species!), and I agree with everything Matt said.

First, I have never had adults going into hibernation. The reason - living in a warm country, it was very difficult to artificially create the conditions required for a cold period (I did not have a room with temperature control at the time). Nevertheless, the beetles had a period of inactivity a few weeks after emergence from the pupa cells, they would just sit burrowed in the substrate and not go out. Maybe they are not sexually mature during this time (it is common in insects that adult females emerge with underdeveloped ovaries and require time for their eggs to ripen).
Second, I agree completely with Matt's statement regarding light for adult beetles - the more lit the container is, the better! Cetoniinae beetles like to crawl, climb and fly all the time. If the container does not allow any light to go through they will just sit there and do nothing. Light also stimulate them to mate.
Instead of supllementing my beetles' food with honey and yeast, I actually gave them pollen (bee pollen granules), bought from natural foods store. This stuff is not cheap, but flower beetles go crazy for it, and I believe it positively contributes to their longevity and reproduction. I have never tried yeast (it might do the same), I will experiment with it on the next generation of flower beetles I get.
Larvae of Cetonia aurata are not cannibalistic, but overcrowding creates other problems, like competition for food (can later result in smaller adults) or infestation of harmful pathogens that can kill the larvae.

By the way naftaliin, I like your user name!

 
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Update on my Cetonia aurata.

I can report that indeed there is a period of inactivity after adult emergence. In my case it was about 4 months. No cold period was used so it might not be necessary but can´t confirm this before eggs are laid. I kept the box with rotten wood on a windowsill (temperature around 25 degrees C). and one day noticed crawling around and trying to fly. At that point they became really hungry and started eating a lot. I used the apple and pollen diet (they indeed go crazy over pollen). Some mating occurred too! Haven´t looked for eggs yet. I might need a bigger box, as I only have about 5 cm of substrate and I´m not sure whether they will lay eggs in there.

 
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