The tick is found in some medieval encyclopedias. It is an insect that always has its head buried in an animal to suck blood, sometimes taking so much its body bursts.

The name engulas used by Thomas of Cantimpré may be a corruption of the name anguillas, the eel, which also sucks blood (i.e. anguillas to angulas to engulas). The name thecam/theca is a corruption of caeca, tick.

The name engulas can also refer to the louse.