Bee larvae turning into cocoons
Have spent some days off, back in the countryside, I have been try to follow their development after the 6 week period of adult life. The tubes as ever allow me into their otherwise hidden private world.
The bee larvae are no longer clearly visible, and more cocoons are in place. It is interesting that being of freshly spun silk that they appear not white, but golden brown (and moist) at this initial stage of metamorphosis.
Here is the first photo of the tubes to the left side of the box (annotated for interest):
My notes:
- In the photo of this outer cell, the pollen stock and larva is apparently gone without a trace. However on closer examination with more light, it looks like a tiny golden brown blob (a cocoon?) appears lodged between the wall line of the first and second cells, and similarly one between the second and third partition. Could then the moistness of the new cocoons allow the expansion of the bee as it goes through its transformation? My initial impressions of other cocoon sizes made me think that they were males. However the cocoon starting size is very probably a function of the larva size from its available pollen stock before it starts spinning its cocoon.
- There is an extremely large stock of nectar/honey in this back cell of three. The reflecting flash of the photo seems to have missed capturing the off-white lava that appears to still be feeding. Bearing in mind that there are several stages of larvae present, I suppose I can assume that logically, the larva will only start the metamorphic cocoon stage when all food is gone.
- This tube, four levels down, is a bit of a mystery. It looks like pollen is smeared all round the surface. [Perhaps the female bee had a bad dose of hay-fever that day before sealing the hole!?] Perhaps the stock of pollen is so great the larva has yet to munch through it. I will try and write an update.
- A newly spun cocoon.
- Newly cocoon - its near mature adult bee size is what led me to initially think that n°1 had disappeared.
- As of today (25 June) the two cells either side of n°6 have their larvae visible, see as the white parts in the tube.
- This may be a humidity issue creating a furry mould on the pollen. Several cells were seen last year when the summer was constantly wet, however to the left side there appears to be the edge of a cocoon. Like those cocoons last summer, this may not be the end of the solitary bee larva. The suspected mould may not be damaging to the young bee, nor may it necessarily degrade the cocoon.
- This is the real curiosity. I will have to check my photos, but I remember that as one of the last cells to be created, it pretty soon seemed to fill up with at least ten thinner and longer squirming larvae. However even more curiously, a week later only one very large and very ‘real-time’ wiggly larva (maybe light-sensitive) remained. Had it cannibalised its siblings? Whatever this mini-monster is, it has already gone into the cocoon phase. Perhaps it is a parasitic wasp that has fed off the work of the last bees, perhaps it was some mites which appeared hovered mainly around the paper tubes. I hope that in fact it is one of the other bee species that appeared late in the day. Update: Will post soon with pictures taken of the monstrous developments.
All these observations are possible because of my choice of clear see-through PVC tubes. Although it is environmentally unfriendly and doesn’t happily bio-degrade, they can be re-used. So I think it is serving a positive purpose here.
As I have had a bit of time today, I made one last photo of the artificial bee habitats that I am using. Or should I say, will use. The commercially bought plastic honey-comb blocks when delivered were off-gassing considerably. I placed one next to my main block when the bees were active, but none were occupied. So they will be left to winter outside - hopefully to be ready for next season.
Tags: humidity, off-gassing