Blow flies are usually the first insects to come in contact with carrion because they have the ability to smell dead animal matter from up to away. Upon reaching the carrion, females deposit eggs on it. Since development is highly predictable if the ambient temperature is known, blow flies are considered a valuable tool in forensic science. Blow flies are used forensically to estimate the PMImin (minimum post-mortem interval) for human corpses. Traditional estimations of time since death are generally unreliable after 72 hours and often entomologists are the only officials capable of generating an accurate approximate time interval. The specialized discipline related to this practice is known as forensic entomology.