The reproductive biology of the leech Helobdella stagnalis (L.) in Utah Lake, Utah

The reproductive biology of the glossiphoniid leech Helobdella stagnalis in Utah Lake, Utah was studied for an 18-month period from June 1970 to December 1971. In this lake it was found that the overwintering adult leeches produce two broods of young in May and June. Evidence is presented to support the idea that the same individual can produce two broods. Two complete cycles of gametogenesis also take place. Continuous water temperatures were recorded at the study site to correlate with reproductive activity. Gametogenesis appears to be temperature dependent with the first generation of sperm taking 4 months to be produced in the fall and winter months while the second generation of sperm is produced in 6 weeks during the spring. Egg production follows a similar pattem.