Here is the full list of all 19 Insect Seeker achievements.
Finish first begginer Level
Finish 50 levels
Finish 100 Levels
Finish 150 Levels
Finish 200 Levels
Reach 400 Stars
Reach 800 Stars
Reach 1200 Stars
Reach 1600 Stars
Finish 50 levels in 2 minutes
Finish 100 levels in 4 minutes
Finish 150 levels in 6 minutes
Finish 200 levels in 8 minutes
Unlock Hard difficulty
Unlock very hard difficulty
Unlock hardcore difficulty
Unlock impossible difficulty
Finish one impossible level
Use all the bonuses of a level