The Grasshopper
The grasshopper in itself is a symbol of irresponsibility and negligence. The message of the old fable, which is alluded to in this poem, is used in it as well. It proclaims that one should be mindful of the future, of the consequences and not spend time completely irresponsibly.
Day vs. night, summer/warmth vs. winter/cold
There is a comparison between these two opposites. Day is associated with life, summer, warmth and eternity while night is associated with cold, death, winter. The grasshopper enjoys the warmth of summer, the warm days: "And all these merry days mak’st merry men". But, soon the cold and death arrives: "Sharp, frosty fingers all your flowers have topped". Summer is equaled to eternity and cold with the fate of death: "A genuine summer in each other’s breast"; "And spite of this cold time and frozen fate".
Terms and figures from Roman and Greek mythology
Considering the renaissance period when the poem was written, these allusions to Roman and Greek figures is not surprising as it is one of the elements of poetry of that era. Therefore, we have allusions to figures:" Ceres and Bacchus bid good night"; "vestal flames", "This Etna in epitome".