Indeed the Chryssalid (the ******* ******** ) was an iconic enemy in UFO:EU, no mater what, everyone feared coming up against one, especially in the dark and early in the tech tree.
Perhaps change things around a little, for example make it more of a fragile creature and change the effect so that instead of injecting an egg it injects a venom that disorientates the victim for a time causing them to fire on anything that moves, be it alien, goodguy or civi, then after 5 turns the venom kills the soldier or have it cause so much health damage per turn.
It could also open up a research avenue to develop a counter toxin