Observation of Two Cockroaches

I believe I may have mentioned the roaches in our apartment.  A few days ago I happened to see a couple of them doing something I really hadn't expected.

They were bathroom roaches, and when I spotted them they were high up at the juncture of wall and ceiling.  I'd gone in there to take a shower, but I could hear that one of the neighbors was already running one, threatening a hot water shortage, so I was going to wait a few minutes and hope they didn't take too long.  But I wasn't the only one who could hear the noise.

The two roaches were a large female, about half an inch long -- I could tell the sex because she was hauling around a distended ootheca -- and a smaller bug, about a quarter of her length.  What caught my attention was the way they were huddled together: the small one was right up close to the larger one, face to face, and the larger one's antennae twitched and flicked around the smaller one, while the small one's antennae continually tapped and brushed the larger one's antennae and face.

When the shower from next door stopped running, the large female's antennae relaxed, making slower sweepes around the little one.  I stood on the toilet to get a better look, and the antennae snapped to frantic attention again, relaxing only slightly when I stood down.

When I started my own shower, the noise spurred the roaches to further action.  Very slowly and carefully, the large one began backing up, continually stroking the air around the little one and keeping it within her antenna radius, and the little one followed until they had backed up to a little pit in the ceiling stucco.  The large one then prodded the little one into the small hole, until it was almost entirely hidden inside, and then stood over the hole, still whipping her antennae around virogously.  They remained like that until I left.  When I looked back in a short while later, they were both gone.

It's difficult to interpret this behavior without falling into overly anthropomorphic language, but at the very least it's a more complex interaction than I expected from roaches, and finding a pit to hide the smaller bug in is more goal-oriented processing than I would have credited previously.  And of course, for all I know, as soon as I left she could have eaten the little one.

I set out a sort of roach trap, a pickle jar with some aromatic food for bait and a bunch of crumpled paper for hiding places, in the hope that if I provided a preferable place for the pregnant female to brood, I could trap and release her outside the apartment and away from people houses.  It didn't work, though.  She's clearly too clever for me.