Fruit Fly Pun-ishment

Two scientists met at the coffee pot.  The first scientist complained with a sigh that his colony of fruit flies never mated in his glass test enclosure. Given that his experiment required several generations to complete, this was a major problem.

The visiting scientist told him that she had experienced a similar problem at her lab, and it was caused by the slick glass walls of the mating arena. The flies of this particular strain of Drosophila keep sliding off and can’t mate. “Your glass is too slick,” she told him, “but I have just the remedy!”

The second scientist asked for a bottle of table salt and some flour and water. She mixed the concoction and brushed it on the glass walls. The flies began crawling along the surface and mated immediately.

“My problem is solved,” exclaimed the first scientist. “If only I had known that flies need monosodium glue to mate!!”