Why do mason bees generally lack the instinct to aggressively guard an area?
Answer
They do not live in a colony with a store of honey to defend.
Since mason bees are solitary and do not maintain a hive or stores of honey, they lack the instinct to aggressively guard a site.

Related Questions
What genus do mason bees belong to?Which gender of mason bee possesses the ability to sting?Why do mason bees generally lack the instinct to aggressively guard an area?Under what circumstances are mason bees most likely to deploy their stinger?How is the physical sensation of a mason bee sting often described?What is one reported difference between a mason bee stinger and a honeybee stinger?What temperature threshold generally indicates that mason bees become active?What is a key misconception about mason bee behavior that is entirely false?What is the primary purpose of the modified ovipositor in a female mason bee?If a sting occurs, what is the recommended first step for cleansing the affected area?