The crotch hugger needs extremely long to mate. After inserting himself, he folds over and grabs around the abdomen. He stays attached that way for a day or two, humping away and spurting his seed from time to time. To get on with their duties, scientists just put on labcoats and carry them around all day. You can sometimes see a scientist sitting at their messhall table obviously having a hard time keeping it together. Also some humping motion under the coat.