Cactoblastis cactorum 

At the 2015 Easter Camp my attention was drawn by a photographer to larvae on a pear cactus genus Opuntia. These two photos were taken late in the afternoon.

 

 

The larvae are about 2 cm long.
The next morning  the larvae were gone. Evidently they had burrowed into each of the leaves
and were enjoying a meal.
 
All the images that follow are copied from Wiki Commons and gratefully acknowledged.

 
Cactoblastis cactorum moth 




The Cactus cactorum  moth




Lays an egg stick on an ear. The stick is small and mimics a cactus spine.











The emergent larvae may initially be cream or pink eventually brown and  black.
What happens next is explained in Wikipedia:
Larvae will typically spend two months within the host cactus during the summer, and approximately four months during the winter. Mature larvae exit the cactus pad to form cocoons. They pupate under debris on the ground at the base of the plant. As soon as the moths emerge, they search a mate, and usually reproduce three to four times within their lifetime. The average longevity is nine days for females and eleven days for males. During this time, the female moth does not eat; she uses all of her energy to travel up to 10 kilometres (6 mi) in search of dense cactus patches for reproduction. The male moth devotes his energy to maximizing his mating opportunities. Males mate between two to five times, and wait two to three days on average between mating events.

The full article is at:
http://en.wikipedia.org/wiki/Cactoblastis_cactorum#Reproduction_and_lifespan