According to Greenberg, 'Electric Insects' was the preferred euphemism which Crumb used to describe the attack helicopters being symbolically referenced by the music being played contra-tonally by high pitched violins to a rapid tempo. According to Robert Greenberg, the opening threnody is symbolic of the attack helicopters used predominantly during the war in Vietnam as a principal instrument of warfare preferred in American combat operations in the field.

The work, as a threnody, is written as an ode or lament for the progress of the Vietnam War. The work references the second movement, Andante con moto, from Schubert's 'Death and the Maiden' String Quartet. The piece is notable for its unconventional instrumentation, which calls for electric string instruments, crystal glasses, and two suspended tam-tam gongs. Crumb numerically structured the piece around 13 and 7, as numbers traditionally related to fate and destiny. The Latin phrase in tempore belli, in time of war, written into the score by Crumb is a reference to the Vietnam War taking place at the time when Black Angels was composed. It was composed over the course of a year and is dated 'Friday the Thirteenth, March 1970 (in tempore belli)' as written on the score. 66304, copyright 1971), subtitled 'Thirteen Images from the Dark Land', is a work for 'electric string quartet' by the American avant-garde composer George Crumb. Black Angels (Edition Peters, New York, no.

Black angels crumb