Board Thread:Questions and Answers/@comment-8824634-20130921175839/@comment-24020550-20131006231122

Well, remember, we're talking about an alien race that we're not really sure HOW they reproduce, so it's not certain if they really even HAVE genders.

That being said, this is a piece of trivia from their page on this wikia It's probable that they're like a hive-mind since it seems all these workers doing the Prime's bidding, so it's possible that it's like the 'mother' but at the same time it's 'male' if we consider the idea of budding or offshooting in axesual reproduction.
 * It is unknown if there are male and female Kraang, but a comment made by a Kraang in "Metalhead" ("The comment that is made by you shows ignorance of Kraang. The ones known by you as 'mother'-) indicates that they may reproduce asexually, or by some other means that does not require mating.