Movie that i cant remeber?

when i was lil i watched this movie i remeber bits and pieces but its about these slug type things i think there slugs and it attacks ppl and kills them and with each person killed it grows bigger but theres this boy who is strange he never talked and i rember him always carrying a lunch box when him and the slug meet the boy turns into this yellowish alien and attacks the slug thing and they explode does anybody remeber this movie if u do plz help me with its name its not a old movie maybe made in the last 20 yrs thank you.