What is this insect (possibly a cockroach)?

Question

I'm looking to identify this insect, found inside a (basement) bathroom by the sink. Wondering if it's perhaps an oriental cockroach / water bug, but the images don't look quite the same, and the bug didn't run from the light like most cockroaches would. The size is also wrong - this one was only about half an inch long, approximately 13 mm.

Note: this is the second odd bug we've found inside; the first looked like a wood roach (but now I'm second-guessing that identification).

I'm located in the northeastern US, in Massachusetts. Both bugs were found in the late evening, if that matters - between 8 and 9 pm.

Answer 1

The bug pictured is not an Oriental coachroach but a female Uhler's Wood Cockroach (Parcoblatta uhleriana). And according to wikipedia:

Parcoblatta uhleriana, the Uhler's wood cockroach, is a species of Parcoblatta native to the United States and Canada. It is a forest species also found in disturbed and urban environments. The male of the species flies freely, while the female does not fly

Identification

This species can be narrowed down to the family Blattodea (Coachroaches and Termites). Due to the flat, oval-shaped bodies with six legs and long antennae.

From there, the genus is easily determined as the genus Parcoblatta, better known as North American Wood Cockroaches. This helpful article describes wood cockroaches:

Their body color ranges from a light reddish-brown to dark brown. The outer edge of the “shield” immediately behind the head is paler in color; these pale edges continue onto the wings of the adult males. Wood cockroaches have long antennae and legs; the legs have distinct spines along their length

Determining an exact species is a little bit more tricky. As there are four different types of wood cockroaches that live in the Massachusetts area:

• Virginia Wood Cockroach (Parcoblatta virginica)
• Pennsylvania Wood Cockroach (Parcoblatta pennsylvanica)
• Western Wood Cockroach (Parcoblatta americana)
• Uhler's Wood Cockroach (Parcoblatta uhleriana)

Fortunately, because the bug pictured happens to be a female there are a few discerning features that aid to narrow down the species. The shiny black color and separated tegmina are two features that instantly classify this bug as being Parcoblatta uhleriana:

Females are readily distinguished from allied species by their short, separated tegmina and shining black color, while males are more difficult to separate from P. fulvescens and P. virginica.
Source: https://en.wikipedia.org/wiki/Parcoblatta_uhleriana

Confirming Media

Here is an Oriental Cockroach (Blatta orientalis), note the similarities and the differences:

Image one referance: https://www.inaturalist.org/photos/78245311, Photo 78245311, (c) Sequoia Janirella Wrens, some rights reserved (CC BY-NC), uploaded by Sequoia Janirella Wrens Image two reference: https://www.inaturalist.org/photos/305200867, Photo 305200867, (c) Dave Eib, some rights reserved (CC BY-NC), uploaded by Dave Eib Image three reference: https://www.inaturalist.org/photos/37765231, Photo 37765231, (c) Katja Schulz, some rights reserved (CC BY), uploaded by Katja Schulz

Answer 2

This is guaranteed to be a cockroach. The head shape, antennae structure and pronotum (the little plate on top just behind that partially hides the head), as well as the 2 cerci at the tip of the abdomen and the overall flattened shape are all classic roach anatomical traits. It may be a nymph of a winged species, given the spike-like structures in the metathorax look a lot like underdeveloped wings. That said, it does seem different from an oriental cockroach, especially given the strange shape of the mesothorax, even if the overall appearance and behavior seem rather similar (oriental cockroaches can grow to up to an inch, are similar in color and have wings, but don't fly and are not particularly fast or good at climbing). Them not immediately running away from light isn't exactly a guarantee that they're not roaches, as members of many different cockroach species won't always book it the moment they're exposed to light, potentially an initial freeze reaction to try and remain unnoticed by not moving (which makes it all the worse when they feel they're not safe and suddenly start running away).

(an oriental cockroach - picture from planetnatural.com)

It is guaranteed to not be a waterbug. Those guys aren't cockroaches, but a species of aquatic insects related to stink beetles. they have piercing/sucking mouthparts, lack antennae and have a different limb structure, specialized for swimming and grabbing prey, while this bug has a limbs structure more similar to a cockroach and better for moving fast on land.

(Waterbug and cockroach compared - picture from family handyman)

This side by side comparison of an American cockroach and what seem to be a giant waterbug or a similar species shows it well: The water bug has large raptorial front limbs and lacks antennae. Its head is also more visible overall.