In the various forests of the realm, there can be found an arachnid that is commonly called a Black Widow. Such spiders are usually found in large numbers, preferring areas that are cool and dark.
 
They will eat other large insects, small mammals, and the occasional humanoid using thick webs to bind them and use their lethal poison to finish the job.  The black widows can vary from six inches, upwards to three feet in size.
 
To secure this poison, we use decoys that the widows attack, depositing the raw serum. When full, my apprentices collect them and process that into a superior form of poison that can be used for any number of studies. This allows me to bring this substance to those seeking to study it. Corked and sealed in a vial, to preserve its potency. Sufficient for all magical potions, magical studies, and spell components.