Police have asked people to be vigilant following 13 reports of business burglaries in March and further incidents in April.
Criminals have targeted cash and cigarettes inside stores and have threatened staff with violence.
Officers have said that this has been done verbally in the hope of workers surrendering goods out of fear.
In one incident a man entered a store in Hill Street, Essington, at about 1.35pm on April 11 and threatened the store worker with a weapon.
The alarm was actuated and the offender left the scene empty-handed.
Chief Inspector Giles Parsons, force lead for business crime, said: “Officers are investigating reports diligently and supporting business owners who have been affected by this wave of criminality.
“Several of these reports indicate that convenience stores are being targeted by offenders who are using threats of violence to obtain cash and valuables.
"They will usually attempt these burglaries during off-peak times, sometimes waiting for customers to leave the store before they carry out the crime.
“Business owners should ensure their premises are covered by closed circuit television cameras, both internally and externally, and maintained thoroughly to reduce the likelihood of a burglary.
“It is best practice to ensure there are at least two members of staff on shift at any one time, particularly during darker hours.
“Ensure that they have access to panic alarms and have an area which can be secured, should they need to protect themselves.”