Biometric parameters

A database on biometric parameters (case length, case width, anterior case surface) is necessary for the computation of hydraulic parameters such as Reynolds number and drag which describe case performance in the flow; weight and volume data are necessary for obtaining density of larvae and cases. In total, there are five larval instars in Limnephilidae, with mineral, cylindrical cases becoming longer and wider with each subsequent larval molt; for the biometrical database, we took larvae sampled in their alpine habitats and preserved in 70% Ethanol. Fresh weight of 72 final instar larvae in their cases belonging to thirteen Drusinae species were measured on a laboratory balance (to the nearest mg). For obtaining volume data of larvae plus cases (to the nearest 0.01 ml) a burette filled with water was used. For each individual specimen we removed excess conservative fluid with filter paper and took the difference between volume readings without and with larvae. Aspect ratios Γ were calculated by dividing mean case length L by anterior case width 2R. Length and width data (to the nearest 0.01 mm) were measured under a dissecting microscope using an ocular micrometer. Calculations of the projected frontal surface areas were based on maximum (anterior) case diameters. For submerged weight reduced by buoyancy, the volume measurements of larvae plus cases were multiplied by the density of water at 10 °C and subsequently subtracted from fresh weight. The corresponding biometric data for the five larval instars of Allogamus auricollis (Pictet 1834) and fifth instars of Potamophylax cingulatus Stephens 1837 as well as velocity data acting exactly at the moment of dislodgement (drift entry) were taken from Waringer (1989, 1993) and supplemented with additional unpublished measurements. The biometric database is included in Tables ​Tables11 and ​and22.

Case metrics and hydraulic parameters for the five larval instars of Allogamus auricollis (Pictet, 1834) (A.a. 1–A.a. 5) and for fifth instars of Potamophylax cingulatus Stephens, 1837 (P.c. 5) at the moment of dislodgement (drift entry) of dead larvae (in cases), combining data given by Waringer (1989) with unpublished data

For calculations, a friction coefficient of 0.69 (Waringer, 1989) was taken

Basic biometry of selected lotic Limnephilidae larvae showing instar, fresh and submerged weight, the percentage of submerged weight with respect to fresh weight, volume, projected frontal surface (± 95% CL), and aspect ratio