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Wondered if anybody would give me another opinion on this. Kind of thinking Melitara sp, but can't find any mention of them using Hosts other than Opuntia.

Sure its not mealies?

Very. It only ate one stem, leaving intact spines around empty space, and I think the frame on the right shows the remains of its transformation from larval form. There were also digested cactus-crumbles alongside the downed stem, and they were notably ejected between the spines by whatever had been inside. Thanks for the double-check though.

Edit: Found it in a grafted monstrose Leuchtenbergia today. Seems to have left the Stenocereus rootstock alone.

It is certainly a cactus boring moth. The remains of the pupal cast remains but the moth has gone on to attack yet another cactus. I'm not sure of the genus as there are several related ones to consider. Bad news for a collection but I've only seen them in wild cacti before.
Dean

A. Dean Stock wrote:It is certainly a cactus boring moth. The remains of the pupal cast remains but the moth has gone on to attack yet another cactus. I'm not sure of the genus as there are several related ones to consider. Bad news for a collection but I've only seen them in wild cacti before.
Dean

Thanks for the response. These two plants had been sharing conditions for about 3 months, and I found the pupal casts (and thanks for the terminology) within 48 hrs of each other. No sign of more yet.

I've been skimming "Cactus-Feeding Insects and Mites" by John Mann, and I see lots of mention of reproduction as once or twice yearly events for cactus-boring moths, which may be part of why this isn't an addressed issue in cultivation, and sets my mind at ease to some degree.

Here's a shot of the waste I described previously.

Weird. I get an occasional Tortrix Moth caterpillar, but they stay on the outside and attempt to knit portions of the plant into a protective cocoon. This usually fails on succulents and they are easy to find.

My cacti (mainly Opuntia species) are all outside planted on mounds but they are parasitized by several species of moths and a cactus beetle. I have some loss of pads each year to the moths. The cactus beetles I keep under control (more or less) by carefully inspecting the plants but the moths cannot be controlled easily. I guess if I had them in a greenhouse I'd still have some problems. Systemic insecticides will cure the moth problem in the greenhouse but for me, I then would run the risk of killing pollinators so I just hope for the best each season. The problem is certainly made more difficult by the thousands of Opuntia plants on the hillsides within a half mile of my cactus mounds.
Dean

Omg!That was a mouth casing ewwwww! I can't even look at it now before i just assumed it was something else or tried to tell myself that, eww so gross, i hope u get that moth, so scary to think they'll be nesting inside yr cacti!!!

Caught one while he was still munching. A close look at the plant revealed an entrance hole and some die-off, and squishing the plant slightly got him to come out. Just thought I'd share a photo of the culprit.

I get the purple borer moth attacking my Peniocereus greggii every year about this time. They bore into the the brand new stem growth at the tips and at the base of the fruits. It looks like sap where they bore in. The caterpillars cause a lot of damage .