Borers, Grubs, Weavils or what?

About 2 months ago I cut down some Cypress trees (macrocarpa), Logs were stacked in a heap of the ground, some smaller branches were left lying around .
The other day I puled a piece of bark off a branch and found these grubs between the bark & the sapwood.
What are these and are they a problem? Are these the grubs that are normaly responsible for the holes that we find in the sap wood of old dried cypress wood?

Any info would be great
cheers,
Dean.

http://www.spray-tech.com.au/timber/borer1.jpg
sapwood

http://www.spray-tech.com.au/timber/borer2.jpg
bark

http://www.spray-tech.com.au/timber/borer3.jpg
close up of the grub, they are about 4mm in length & 2mm width

dean,i think they're just your standard wood grub that just happens to love the sap wood of macrocarpa.they don't seam to eat the heartwood and i don't find them eating any of the other logs i have in the yard.and they leave great patterns in the timber if caught early.leave it too long and they eat all the sap wood leaving only dust.hope someone else can shed some more light on them regards andrew