Unless you are to target underground for the wurms, you merely find many insectoids and reptile like creatures. They do not carry supplies for the other troops however, only enough for themselves to signify their status as expendable units. Especially when you consider what is happening in the second wave, they definitely have just enough to complete their job.
Duplicants come in, shapeshifting to reach their targets faster and attacks them through blades.
Phyrexian Hulks as well come into play here, as brutes, similar to their Guardian counterpart, but more for actual melee attacking instead of standing there.