Development time of the potato leafhopper,Empoasca fabae(Harris), was determined in the laboratory under conditions simulating spring in Louisiana. Development time differences between 4 leguminous host plants were statistically significant but small. All published temperature-dependant models ofE. fabaedevelopment predicted mean development time within 10% of the true overall mean. Field studies ofE. fabaedevelopment in the spring in Louisiana revealed significant but small development time differences between 2 leguminous hosts. Model predictions were generally within 10% of the true mean development time. This result was robust for 5 different sources of temperature data. Any of 3 published models ofE. fabaedevelopment are recommended for use with maximum and minimum temperature data from standard weather stations for predicting mean development time of migrant source populations. It is recommended that host-plant effects not be included.