Pecan tree grub

Ok, so we moved into this house just about 4 years ago, it has a few mature trees on it (all are about 50 years old) one being this pecan tree which is in poor shape and I have been trying to save it threw correct trimming, good food, watering and what not. So this tree went from about 60 foot to 30 foot threw last 4 years of trimming some the first year and then this year we decided it would be ok to trim it again since it had rebounded so well and even gave us some decent pecans this year, we were stoked to say the least!
Well, we decided to keep the trimmings and use as fire wood in the outside pit, as my wonderful husband was spilting wood here come these grubs!
They are HUGE...my questions are:
#1. Is this grub destroying my tree from the inside out or did something deposit the eggs after the tree limbs were cut down and piled.
#2 What is it? I am not sure the orange one is the same type as the others since it has different mouth parts and legs, the white ones don't have legs. Let me know if I am wrong.
#3 How do I treat the tree for these icky things if it is infested, I would really like to save this tree.

Thanks for any help Floridaheat

YUCK !!!

The big ugly ones are some type of borer larvae. Not sure if they are after the dead wood, or if they are pecan borers. Wood boring insects are hard to control. Imidicloprid might work, but read the label before using on any kind of fruit/nut tree.

Have you inspected your tree for any signs of borers? Imidacloprid can be used to control borers but I wouldn't use it or any other systemic product if you're planning to eat the pecans. Here's an article about borers & borer control from the FL extension office that you may find helpful: http://edis.ifas.ufl.edu/mg007

ecrane3
I have inspected the tree and don't see anything unusual, even the wood untill it is split shows no signs of any damage with exception to wood peckers.
I was thinking maybe I would take a small portion of the wood put it in something that has some airation and see what those yucky things end up being.
I will go to the FL Extension site and check that out...thanks for the link.
Calalily
I will look into Imidiclprid
JoParrot
Yes, your right "yuck" try getting them not to wriggle around trying to get a photo...I didn't want to touch them!

Thanks for everyones help so far

Floridaheat, you can probably take the grubs and some of the wood in to your local extension office. If you have a good agent (we don't, ours is an idiot), he should be able to tell you what it is or at least send it out for a diagnosis.
Woodpeckers like to eat grub worms and will drill holes in trees to get to them.