We report an uncommon case of a primary Echinococcus cyst that developed in the subcutaneous tissue of the right popliteal fossa, at the spot of a previous wasp sting, suggesting the possibility of an unusual transmission of the eggs by insects. This unusual presentation was initially considered as a Baker cyst until parasytological results verified Echinococcus hydatidosus, the larval form of Echinococcus granulosus, as diagnosis. However, the most common path of Echinococcus granulosus infection is through contact with a definitive host or by ingestion of ova through contaminated water or food. Transmission by insects should also be reconsidered in endemic areas.

Keywords: hydatid cyst , insect sting , ultrasonography