I think, the the insects are least of your worries. There are much worse torments.
When you are in Grave and if you had been a good person, then you won’t even think about that, because you’ll see your place in Heaven and as for disbeliever, it is worse much torment. And do not worry about your body, because God Almighty Says:
“And the Trumpet will be blown (i.e. the second blowing) and behold! From the graves they will come out quickly to their Lord.” (Quran 36:51)
This means that, your body will be restored after it has been decayed. So don’t for this, just, stay relaxed and fulfill the job that God has given you to do and that’s it.