Bananas.org - Pitaya pest..

I have a habit of checking my new plants in the house 2 times a day for the first monh or so for possible "extra cargo" that could have came in with the shipment. So, following my routine, I checked my DC, looked good, checked my newest addition of purple passion plant, nothing unusual there, check my pineapple, stressed but pest free. Lastly, I checked my 4 pots of pitaya, well, last few days I have been picking aphids off of it (first noticed on tuesday as 3 small groups congregating on 3 new growth areas which were dealt with with a vengeance) and each day since wednesday there have only been maybe 1 or 2 a day on them and were removed. BUT, lo-and-behold, checked them last night before bed and all was well, got up this morning and one new growth tip (just happened to be the one growing the best so far too) was almost completely severed all the way through. And, the cut was pretty fresh.
So, from there I proceded to check all my plants thoroughly and the room for that matter (i.e. floor, tables, chairs, everything) for any signs of anything.......come up with nothing.
Any ideas as to what might be doing this to my cacti?
Side note* other than aphids, I found 1 larvae of something, not sure what it was but I killed it. The larvae was roughly 3-5 mm long, less than 1 mm thick, very slender white with a black head, and spins silk. It looked like a super tiny white inch worm. It was very hard to see and the only reason I found it was I thought it's head was an aphid on an area of white scar-tissue.

Shaggy