"Species needs" or species being refers to the notion employed by Karl Marx that humans fulfill themselves -- both individually and collectively -- through the labor we perform. Here, Marx defined Labor broadly as any act performed in or on Nature. It is our relationship with the external world, our ability to turn nature into other things (our ability to produce) that defines us as subjects, or human beings.  However, when labor becomes alienated, humans are no longer fulfilled by their work, and the individual becomes disconnected from her "species being."