Lectoblixes are a species of blix. They age quickly, and survive by draining the youth of others. In Secrets of the Dragon Sanctuary, Torina Barker reveals herself to Kendra as a Lectoblix. Held captive with Kendra are several of Torina's elderly victims. Out of 'kindness' she allowed them some years left to live, but others she absorbed all youth from until they perished from old age.
However, lectoblixes have a weakness. When a lectoblix tries to drain a unicorn, they exploded as the amount of youth and purity inside a unicorn obliterates them. This was demonstrated when Torina attempted to drain Bracken.