When this spell is cast, the priest creates an invisible barrier to all sorts of insects, and normal insects do not approach within 10 feet of the caster while the spell is in effect.
Giant insects with Hit Dice less than 1/3 of the caster's experience level are also repelled (for example, 2 Hit Dice for 7th- to 9th-level casters, 3 Hit Dice at 10th through 12th level, etc.). Insects with more Hit Dice can enter the protected area if the insect is especially aggressive and, in addition, rolls a successful saving throw vs. spell. Those that do sustain 1d6 points of damage from passing through the magical barrier. Note that the spell does not in any way affect arachnids, myriapods, and similar creatures—it affects only true insects.
The material components of the repel insects spell include any one of the following: several crushed marigold flowers, a whole crushed leek, seven crushed stinging nettle leaves, or a small lump of resin from a camphor tree.