Did you or somebody observe how there aquatic beetles lay eggs? They should lay eggs inside the tissue of aquatic and semiaquatic plants. If you have obseved the oviposition in your aquarium or at the laboratory, I will be pleased to communicated with you. I study egg-parasitoids (chalcid wasps) who are parasitizing eggs of aquatic and semi-aquatic beetles and water bugs, dragonflies and some other aquatic insects and even aquatic spider!. Keep in touch, Viktor ufensia @ gmail. com