Which type of cockroach is known for overwintering outdoors and entering homes through floor drains?

The Oriental cockroach is known for its behavior of overwintering outdoors and is often found entering homes through floor drains. This species thrives in cooler climates, which allows it to survive winter conditions outside. When temperatures drop, Oriental cockroaches seek refuge indoors, particularly through areas such as floor drains, where there may be moisture and organic matter that provide food and breeding sites.

In contrast, other cockroach species, like the German and American cockroaches, typically have different survival strategies and habitats. The German cockroach is more commonly found within buildings and does not usually overwinter outdoors, while the American cockroach prefers warmer conditions and tends to dwell in outdoor environments or basements. The Australian cockroach, while also a species that can be found outdoors, is less associated with wintering behavior in northern climates.

Thus, the behavior of overwintering outdoors and the tendency to enter homes via floor drains distinctly characterizes the Oriental cockroach, making it the correct answer.