Your scenario does not make it clear as to whether you were using the same jar on each of the three occasions. The reason why this is important to any analysis is whether you can demonstrate that you opened a sealed jar with which no one else could have tampered and thus the beetle was ipso facto in the jar at the time that it left the manufacturer.
A product is defective if when it left the manufacturer it was in a condition that is unreasonably dangerous or not fit for ordinary use. A jar that contains a beetle would violate this standard and thus most likely create some form of liability. The problem in such cases is damages. You have not indicated that you ingested the beetle or in any manner were harmed by its presence in the jar, other than that you most likely have paid for a jar which is inedible. In such product liability cases, some claimants assert emotional distress claims. Emotional distress claims are hard to prove objectively. in most cases, contacting the manufacturer and asking them to address your horror and make it right as a matter of business judgment is the best course of action, as opposed to trying to bring litigation.
Answered on Dec 04th, 2013 at 1:30 PM