from ID Request.

Here is one web site with some information on the genus.

unlike Cactobrosis, these live communally, and they are larger in size. There are at least three species in the region, and I'm not sure which it is - M. dentata, M. doddalis, [i]or M. subumbrella[/i]. I've never learned how to tell the species apart as larvae, though it may be possible. They are among the few insects that I kill whenever I find them at my home (wasps, flies, tarantulas, scorpions - all are OK), because I am also a Cactus grower - and these critters are devestating to Cacti. They are especially fond of Opuntia (Pricklypear).

Close relative of Cactoblastis (which are red instead of blue).

Like Cactoblastis, they lay eggs in stick-like strings, attached to the spines, which mimic the spines.

The adults are stick-mimicing "Snout Moths", commonly attracted to lights through a rather long period, mostly from late spring to autumn (depending somewhat on the species.

...if you crop your pics as close to "just the bug" as possible. Only you and the editors have the option of viewing the full-size images. Everyone else is left looking at some tiny bugs in a lot of unnecessary background. :)

You can click on "edit" and simply upload cropped versions, if available. They will replace the current images.

Thanks--and welcome to BugGuide!