The blow fly lays its eggs on dead animals to provide food for its carnivorous larvae as they hatch. this means that in nature, the life cycle of the blow fly is part of the decomposition process of dead bodies. The study of this phenomenon by entomologists has lead to our ability to estimate the time since death by examining which state of growth blow fly is in when found on the body. The forensics entomologist conducts examinations at crime scenes and examines the insect evidence found there to bring evidence to court cases involving human bodies. To make a determination, the scientist makes visual observations, collects insect evidence, determines the stages of development, and calculates the time if initial deposit of the blow fly eggs on the body. In the laboratory the scientist rears collected specimens to confirm the species and more accurately establish the stage of growth. They then compile their findings and make a "best guess estimate" as to how long the cadaver has been dead.