Growth, Abundance and Distribution of Larval Tabanids in Experimentally Fertilized Plots on a Massachusetts Salt Marsh

Abstract

The coastal salt marshes of the eastern United States provide breeding habitats for several species of biting flies of the family Tabanidae. The larvae are found in the sod of the marsh where they spend a year or more before pupating and emerging as adults in the summer months. Many investigators have studied the distribution and density of larval tabanids in salt marshes but few have provided quantitative data on the seasonal abundance and distribution of larval horseflies. No one has evaluated the effect on them of the contamination of coastal marshes with nutrient-rich waste water. In the present investigation small areas were sampled intensively to estimate the abundance and distribution of tabanid larvae on a salt marsh, and to study the effect of experimental nutrient enrichment simulating eutrophication on larval tabanid populations. In addition, the feeding preferences of the larvae of Tabanus nigrovittatus Macquart, the major horsefly in Massachusetts marshes, and the role that cannibalism may play in regulating larval numbers and distribution were investigated.