Determining dry weight and percentage dry matter of chironomid larvae

Abstract

Reproducible live wet weights may be obtained for medium to large larvae of Metriocnemus knabi and Chironomus attenuatus after blotting them on filter paper for 1 min. To obtain reliable measures of wet weight for smaller larvae the blotting time must be reduced in proportion to the surface area/volume ratio of the larvae. Dry weights are easily obtained by oven drying at 60 °C for 24 h but drying for several days does not affect the results. A temperature of 100 °C decreases die percentage dry matter in C. attenuatus. Both species display an increase in percentage dry matter with increasing size. The extent to which the gut is filled with food has no effect on the percentage dry matter. Attempts to determine dry weight directly from preserved larvae were unsuccessful.