Life history information is important in understanding structural and functional roles of macroinvertebrates in aquatic environments. Most alderfly investigations have been in the temperate regions of North America and Europe. Sialis velata occurs in 19 states, yet no life history determinations are known for the species. Populations were collected semimonthly (warm months) and monthly (cold months) in a reservoir and river in central Texas. Determinations of instar numbers, feeding habits, pre-pupae emergence, and comparisons between lotic and lentic populations were analyzed. Head capsule widths (mm) were measured for instar determinations. Gut analysis was performed to analyze feeding habits. Pre-pupae were collected using traps along the shoreline. Head capsule width data collected 20 times over a 12-month period shows at least 4 ranges occurring at each sample date and progressive increases in size over time. The lotic populations exhibited an accelerated growth rate and accelerated pre-pupa activity, probably due to increased temperature.
Species 1: Megaloptera Sialidae Sialis velata (alderfly)
Keywords: life history
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