Females of giant water bug species glue eggs to their mates' backs via bodily secretions that act as a type of waterproof glue.

References

"Using bodily secretions, the female [giant water bug] glues the eggs to her mate's back." (Crump 2005:52)

Book
Headless Males Make Great Lovers: And Other Unusual Natural HistoriesUniversity of Chicago PressJanuary 5, 2007
Marty Crump

Living System/s