Someone PLEASE help, Is this the movie I'm thinking of???

Ok, someone please tell me if this is the movie I think it is...

I was really young when I saw a horror movie my uncle rented, and I've spent literally my entire life looking for this thing and can't find it, I have no idea of the the title or actors in it or anything, all I remember are some images from the film and a vague notion on the plot.

The other day I was watching a retrospective on Tobe Hooper's career and had seen everything there with the except of Invaders From Mars....something about it sparked my memories and made me go "Is that is?!?! After all this time, is this that movie?!?!"

So I'll describe what I remember and if its not Invaders From Mars, then PLEASE tell me what on earth this movie could be.

Ok... what I remember is a movie about aliens or some other kind of monster, they may or may not have been insect-like, but I'm fairly sure they were aliens. These things, they eat people, particularly people's heads for no real reason, its just what they do.
A kid in the movie, who I'd guess was the main character figures this stuff out and makes like a mock-up head. I guess he was into horror movie special effects, sort of like Tommy in Friday The 13th Part 4. Anyways, he makes this head, and stuffs it with some kind of explosive, like dynamite, and puts the head on a long pole, and uses it to taunt the alien monster getting it to chase him. The kid finally gets the alien to bite the head off and swallow it and of course the thing blows up and the alien is blown to a million peices.
Now here's where it gets REALLY weird.... the army is there and decides that the only "safe" way to dispose of these monsters is to bury the chunks of them that are left far apart from eachother, cause if they're too close together, they'll fuse back together into one of the monsters. So they bury the chunks of these things in holes set fairly far apart and they end up taking an entire field just to accomplish this. Well after they're done, one of the characters makes this obligalatory "That's the end of that chapter" type of comment, just as the ground starts shaking. Suddenly this GIGANTIC version of the alien rises up out of the ground, made from all the fused together parts of the previous dead ones, and stands like 4 stories tall.
And that's the end...I mean right when it stands up, the screen jumps to black and the credits roll.

I've been looking for that movie since I was 5 years old, and that's all I know about it. That and that scared the living *beep* out of me at that age. When people on the messageboard here started talking about "cliffhanger" ending, I thought again "Is this IT?!!? Have I finally found it after 20 years?!?!"

So, is what I'm talking about the Invaders From Mars re-make, and if not, WHAT THE HELL IS IT?!!?