Dukkha nanas?

Primitive fears of death arise during vipassana practice at certain stages. 

That's really good stuff Nickol.  Realising the true nature of the body helps to cast off identification of the self with the body.  At first it may seem disgusting, but later it just part of the frame of reference.  So this sense of death/bones/anmiated bag of glop filled with obscene goo that you are feeling is an opportunity.  It allows you to practice mindfulness of the body at any time, for any period, even while doing other things.

Here is an extract from Thanissario's tranlsation of the relevant part of the Sattipathana Sutta.

"Furthermore, as if he were to see a corpse cast away in a charnel ground — one day, two days, three days dead — bloated, livid, & festering, he applies it to this very body, 'This body, too: Such is its nature, such is its future, such its unavoidable fate'..."Or again, as if he were to see a corpse cast away in a charnel ground, picked at by crows, vultures, & hawks, by dogs, hyenas, & various other creatures... a skeleton smeared with flesh & blood, connected with tendons... a fleshless skeleton smeared with blood, connected with tendons... a skeleton without flesh or blood, connected with tendons... bones detached from their tendons, scattered in all directions — here a hand bone, there a foot bone, here a shin bone, there a thigh bone, here a hip bone, there a back bone, here a rib, there a breast bone, here a shoulder bone, there a neck bone, here a jaw bone, there a tooth, here a skull... the bones whitened, somewhat like the color of shells... piled up, more than a year old... decomposed into a powder: He applies it to this very body, 'This body, too: Such is its nature, such is its future, such its unavoidable fate."

Edit:  If you want to formalise this, google The Nine Cemetary Contemplations.