What is the meaning of this Shakespeare quote: "A plague o' both your houses!  They have made worms' meat of me!"?

Mercutio has been stabbed during his fight with Tybalt. Romeo had got between them and Mercutio cannot see Tybalt's sword. Mercutio curses bot the Capulet's and the Montague's for his death. The family feud has resulted in his death.