It's a sci fi show, let it go.

Sikozu Svala Shanti Sugaysi Shanu:
Don't you see? No. No! This isn't happening because it is not possible.
Dominar Rygel XVI:
Your brain isn't functioning. Do you think this is all just a hallucination? Do you like that explanation better, hmm?
Sikozu Svala Shanti Sugaysi Shanu:
No, but I simply cannot comprehend
Dominar Rygel XVI:
Neither can I. Who cares? We're here, they did it, and that's that. You consider yourself intelligent?
Sikozu Svala Shanti Sugaysi Shanu:
Yes, I do.
Dominar Rygel XVI:
Then stop behaving like a child.
Sikozu Svala Shanti Sugaysi Shanu:
I am not a child!
Dominar Rygel XVI:
No, you're an infant! You've studied but you haven't experienced. You know nothing of life!
Sikozu Svala Shanti Sugaysi Shanu:
And you do?
Dominar Rygel XVI:
I've been around long enough to know how ignorant I am. I don't assume the universe obeys my preconceptions. Huh! But I know a frelling fact when it hits me in the face!
My counter argument is that I'm offended.

I was curious about this too when viewing the episode. Some questions come to mind:
Could you have a planet with other species so similar to ones on Earth without insects not having evolved at some point?
Maybe they used to have insects but they exterminated them or they died out?
Would convergent evolution make species similar to insects?

Yeah, umnot expecting too much straight science or verisimilitude from Farscape.
Repeat to yourself "It's just a show. I should really just relax."~MST3K
Church | State .

Yes that planet

I wasn't aware that the Ku Klux Klan was in Farscape
oh, you mean the CLAN planet. From A Prefect Murder.
Talyn! You're fahrbot!

Adaptation and evolution means that if that planet never had insects it would be adapted to life reproducing without insect assistance. Besides, insects are not the only way plants are pollinated.