Suppose I have an insect species name (say Carabus nemoralis) would it be possible to obtain even an approximate body size for this animal? Traitbase / EOL seems to have some information, but not necessarily body size.
Brose, Cushing, Berlow et al: Body sizes of consumers and their resources
Here, we try to reduce such limitations by documenting body size ratios for 16,863 consumer–resource links. The data includes body size ratios from terrestrial (n = 12,398 links), marine (n = 2355 links), freshwater (n = 1,983 links) and soil (n = 51 links) ecosystems.
The data set provides, where available, information on consumer and resource taxonomy, their common names, measurements of their body sizes (average as well as minimum and maximum body length or weight), the geographic location of the study, the habitat studied, the feeding type of the link and the species’ metabolic categories (see below for a detailed description).
Links to the data files on that page.