2 1×6= 126 legs

(138- 126)÷(8-6)=6 (only)-Just the number of spiders.

2 1-6= 15 (only)-Only the total number of dragonflies and cicadas.

Assuming that 15 are cicadas, then the wings are 15 pairs, and the number of dragonflies is more.

23- 15=8 (only)

15-8=7 (only)

A: There are 6 spiders, 8 dragonflies and 7 cicadas.