Hilchos Issurei Mizbeiach 6:11

If most of the flour is wormy, or if most of the wheat is wormy and flour is made from it, it is unfit for the altar. If the greater part of a single kernel is wormy, there’s a doubt as to whether it may be used. If meal remains in the flour, it is unfit.

Hilchos Issurei Mizbeiach 6:12

The flour is checked as follows: The Temple treasurer sticks his hand into the flour. If meal sticks to his hand as he removes it, the flour is unfit until it is sifted again. Flour from wheat that grew in an arid plain, in a trash heap, in an orchard, or on land that was not left fallow and worked should not be brought, but if it was brought, it is fit.