Singing Cicadas' Life in Summer

Poor Singing Cicadas

Two dead cicadas were in the balcony of my office this morning. One was hanging on a little tree and the other one was on the floor. It seems they flied inside and ended their lives. They looked like stuffed cicadas and fortunately were not eaten by ants.
As far as I know, they live under the ground about 7 years as a nymph and live only 7~15 days outside. What a short life!
Looks like I become the age in the middle of the birth and death so I am thinking again about the life of any creatures if I saw one of dead creatures.
I thought these cicadas were born in the same year of my boy and he just started to enjoy, learn, creating, and anything he could do with his own will.

 One on the floor.

The other one on the tree.