Final answer:
The character prefers to spend time alone.
Step-by-step explanation:
The sentence that shows that the character prefers to spend time alone is 'Here, without fear of being troubled by the passersby, I could consult the Ammophila and the Sphex [two digger or hunting wasps) and engage in that difficult conversation whose questions and answers have experiment for their language, here, without distant expeditions that take up my time, without tiring rambles that strain my nerves, I could contrive my plans of attack, lay my ambushes and watch their effects at every hour of the day.' The phrase 'without fear of being troubled by the passersby' indicates that the character values solitude and prefers to be alone.