I believe this is Laccophilus pictus coccinelloides.
Tags: arizona,butterfly roadless area roadless area,coronado national forest,diving beetle,la milagrosa canyon,la milagrosa trail,laccophilus pictus coccinelloides,night,pima county,santa catalina mountains,santa catalina ranger district,water

Thermonectus marmoratus.
Tags: arizona,butterfly roadless area roadless area,coronado national forest,diving beetle,la milagrosa canyon,la milagrosa trail,night,pima county,santa catalina mountains,santa catalina ranger district,sunburst beetle,thermonectus marmoratus,water