Insects pass their uric acid through the alimentary canal. Why?
Its not like that. Insects do not pass their uric acid through the whole alimentary canal.
Most of the insects excrete nitrogenous wastes as uric acid in the form of pellet or paste with a minimum loss of water and are called uricotelic animals.
To do this, undigested food particles in the hind gut of insects join uric acid from Malphigian tubules( excretory structures of most of the insects) to form fecal pellets. The rectum absorbs most of the water in this waste matter, and the dry pellet is then eliminated through the anus, without separate release of nitrogenous wastes as occur in most ureotelic animals.
insects have their excretroy products as nitrigenous wasyes which r present in blood . . . moreover their kidneys are present in their alimentary canal only so all these wastes are collected by blood and sent to kidney in the where they get separated and excreted , all these wastes are converted to uric acid . so insects pass uric acid through alimentary canal