Unknown Pest - Hole in growing P. nigra culm

[Carlo]

I have several culms effected by a pest that is destoying them. I have no idea what it could be, it does a thin hole in the culm and then feed itself inside. The result is that the hole become bigger and bigger, and then the pest goes down through the nodes.
Here is a photo
http://www.bamboocraft.net/bamboo/data/527/medium/DSCF0149.jpg (http://www.bamboocraft.net/bamboo/showphoto.php?photo=4276&cat=500&ppuser=2456)

Any idea what it could be?
I have some doubt it is some kind of weevil... but never saw it

[Mark Meckes]

Hi Carlo, you would need to provide a closeup photo to get a better look at it, but from a distance it looks like the outside surface has rub marks around the hole.

Q.
Is it this year's culm or did it emerge last year?
I see it is already beginning to change to color like Phyllostachys nigra does.

Do you have squirrels in your area?
Sometimes squirrels will chew a part of a shoot when it is growing but leave the rest of it alone.

Could there have been anything rubbing on this culm when it was young and tender to make the hole?

I'm just guessing of various possible causes ...
If it was caused by a critter, they may now be long gone, though the hole can be an invitation for another critter to make this cavity their home for a while.
Generally most insects don't bother or damage live bamboo culms after they have hardened. . ... though there are some insects in different parts of the world that can cause damage.

Mark

[Carlo]

Hi Mark,
this pest attacked many culms, the p. nigra was attacked last year, but this
year it attacked p. aurea, and p castillon.
I have some squirrels in my area but it is probably the bamboo weevil.
I found some cocoons in the soil :S :@
There is a nice description of the pest on this website:

http://www.inbar.int/publication/txt/tr13/SHOOTright.htm
Xu Tiansen (1964) has reported the biology of the weevil in detail. The adult weevil is about 15-17 mm long and dark reddish-brown or black in colour. There is a vertically elongate, black spot at the centre of the protergum of the adult. There is one generation per year. In China, adults and larvae occur in bamboo stands from early April to early June and from mid April to mid June, respectively. Adults come out from the soil, where they overwinter, when most bamboo shoots in the stand are about 2 m in height. They feed on sap from the upper part of the shoots and leave vertical lines of feeding holes on the outer surface of the shoots. Eggs are deposited individually in feeding holes and take about three days to hatch. The larvae bore beneath the sheath near the nodes, and feed on branch buds when shoots get older. There are five instars in larval stage. The fully developed larvae drop to the ground, burrow into the soil and pupate in cocoons made up of soil at 8-15 cm in depth. Adults emerge about 30 days later and overwinter in the cocoons.