What does "it" refer to? From where do you imagine that these pests will come from?

If you use clumping litter, you just remove the clumps and turds daily without changing the rest of the litter and the odor control is much better than for non-clumping litter. I recommend the unscented kind because the odor of some kinds of scented clumping litter is almost as obnoxious as the odor of cat urine to some people. If it doesn't say "unscented" or "fragrance free" on the box, it is scented (It is like the manufacturer is trying to fool you.) . The only other disadvantage to clumping litter is that it sticks more to cats so you will find pieces of litter wherever your cats travel. Not a lot, but it is noticeable. Anyway, cat litter is not going to attract pests.

I'm a little puzzled by the rationale for starting wildflowers indoors at all. By their very nature wild flowers are hardy (if they are native to your region). They would be prime candidates for winter sowing or outdoor sowing in spring. In fact they would most likely be far sturdier plants if begun outside as nature intended. I'd keep the indoor seed starting equipment for things which really need it, such as tender annuals.