This cache is located on the Red trail. The Vashta Nerada are microscopic life forms that are harmless in small numbers, but in large swarms they are deadly. The Doctor encounters them in the largest library in the universe, one that encompases an entire planet. During some sort of accident, the library is quarentined and 4022 people are lost. 100 years later, the Doctor and his companion Donna Noble visit to find an archeologial study in the process. It's soon realized that they are all in great danger.
The Vashta Nerada are compared to pirahna, but they "swim" through the air and tend to stay in the shadows. The name actually means "the shadows that melt the flesh." The creatures can even get inside space suits to devour their prey. While they are feasting, they keep the victim alive to move around. A tell tale sign that a person has fallen victim is that they cast two shadows. Once this has happened, there is no saving them. There is no grand plan for this lifeform, it is just a creature surviving.
The Vassar Farm property is open from sunrise to sunset. Coordinates for parking and trailheads can be found on GC54JTT (Little Blue Box) Dogs are allowed and must be leashed. There is a trail map on a kiosk as the main parking area or on their web site at http://farm.vassar.edu/map/ Bikes are allowed, but NOT on the Dark Blue, Green, or Black trails. I wouldn't recommend the use of bikes on the Yellow or Red trails either unless you consider yourself an excellent rider.