Injury of Clover Root Curculios to Red Clover in New Jersey1

Abstract

A 3-year survey of red clover fields in New Jersey showed that high populations of Sitona hispidula (F.) and S. flavescens Marsham were present throughout the State and extensive larval feeding was observed on the roots of seedling and secondyear stands. Sitonids were found, by the use of a soil-filtering process, to be the most numerous of all insects attacking red clover roots. During 1956 and 1957 the average number of feeding scars produced on roots by sitonids during the larval period was 1.18 and 1.26, respectively, or an overall average of 1.22 feeding scars per sitonid. Using this figure to estimate sitonid larval populations from feeding-scar data in plots that were sampled after the sitonid larvae had completed their development and had emerged from the soil as adults, populations of 50 or more per square foot were not unusual and populations as high as 124 per square foot have been found. Estimated populations on a Statewide basis averaged about 73 sitonids per square foot.