Mimic

Mimic is an entertaining sci-fi horror movie about a new species of cockroaches that are developed by Dr. Susan Tyler and her husband Dr. Peter Mann in order to stop a dangerous epidemic. The killer cockroaches are supposed to kill all cockroaches who are the carriers of the virus and then die themselves afterwards, but instead of dying the new species just continue to develop until it becomes an even greater threat. What makes these creatures particularly dangerous is their ability to mimic people's appearance, hence the title.

Don't mess with nature seems to be the underlying moral of this movie as it is in movies like "Deep Blue Sea" and "Jurassic Park".