A survey of aquatic and terrestrial malacophagous insects associated with snails was carried out during 2016-2018 in Sharquia Governorate. Four terrestrial snails and three aquatic snails were collected.  Terrestrial snails were more abundant on clover, wheat, lettuce and faba beans.  Aquatic snails were abundant in rice fields.  Three aquatic and three terrestrial malacophagous insect species were found associated with the above-mentioned snails. Petrostecus barbarous; a terrestrial arthropod; showed individual and gregarious predation on land snails under laboratory conditions. The predatory activity of this species was studied on Monacha obstructa snails and its eggs. The predator became more voracious in case of gregarious predation as well as on snail eggs. Gregarious predationof Pt. barbarous on M. obstructa snails increased with increasing temperatures. Results suggested the possible role of Petrostecus barbarous Dejean as biological control agent against harmful snails.
 Key words: Malacophagous insects, biological control, molluscs, Petrostecus barbarous, Sharquyia Governorate, Egypt
A survey of aquatic and terrestrial malacophagous insects associated with snails was carried out during 2016-2018 in Sharquia Governorate. Four terrestrial snails and three aquatic snails were collected.  Terrestrial snails were more abundant on clover, wheat, lettuce and faba beans.  Aquatic snails were abundant in rice fields.  Three aquatic and three terrestrial malacophagous insect species were found associated with the above-mentioned snails. Petrostecus barbarous; a terrestrial arthropod; showed individual and gregarious predation on land snails under laboratory conditions. The predatory activity of this species was studied on Monacha obstructa snails and its eggs. The predator became more voracious in case of gregarious predation as well as on snail eggs. Gregarious predationof Pt. barbarous on M. obstructa snails increased with increasing temperatures. Results suggested the possible role of Petrostecus barbarous Dejean as biological control agent against harmful snails.