Jennifer - You're right about them not eating the blackworms when the daphnia are available. I've been unable to get to the place I normally find daphnia early enough in the day to get a suitable amount, (or they're declining), so most of my daphnia is being lost when eaten or during water changes for the larva. I've noticed a definate increase in the amount of blackworms eaten with the lower concentrations of daphnia. And as you said, the ones that eat both definately are growing faster, as these are only found in tanks where both are fed.
I have several ~20 gallon plastic totes that I use. The biggest tote has a breeding population of daphnia and is fed blackworms once per every 2-3 days. These are the smallest larva (a. maculatum). They're also the second youngest, but only by about 1-2 weeks. None of these have their rear legs, and are all fairly small. There are 9 in here, big fungus loss during hatching. I thought the whole batch was ruined and put them in with my mudpuppy to see if he'd eat the jelly and it wouldn't go to waste, and then a week later I saw some movement and removed them as a few survivors were climbing out. The mudpuppy totally ignored the egg mass, so I guess reports that they eat amphibian eggs must be limited to frogs at the very least.
In my third tote are the youngest, also a. maculatum. These are slightly larger than the first tote; despite being approximately two weeks younger. They're also the most crowded; this is the only biggest batch and hatched most of the larva, almost no loss to fungus. There's 50 in a smaller container than the 9, yet they're all larger. More blackworms were fed to these (I couldn't get enough daphnia to ensure that they'd be well fed. They still rejected most of the blackworms, hence the small size.)
On the other end of the spectrum are my remaining tiger salamander and two large maculatums. These were from my first visit to the pond, and are the oldest. They were so early that I couldn't get much daphnia and such for them, and fed them exclusively blackworms. They also eat daphnia, but in lower quantities. These got something of a preferential treatment, and have more area per salamander. They also had plenty of daphnia present at all times previous to now, but prefer the blackworms.
Aside from the first and third totes as mentioned above, all the others have rear legs. The third has some rear development but they're small, about 10 or so have this. Only one from tote 1 has rear legs, and they're very small.
One other really interesting thing that I noticed was I went looking for fairy shrimp near Big Falls (30 minutes from the place I got all the other eggs, so I can assume a similar hatch time and temperature) and found several large larva. They were about 1.5 inches long, rather fat, and very dark. They were either a. tigrum, laterale, or maculatum, but they all lacked rear legs. I isolated one and fed him some blackworms and mosquito larva, but I noticed he's getting rear legs now. I'm curious as to whether this is coincidence or not, but the others I captured and did not feed the blackworms have as yet not begun development, it has been 2 full days of this diet.
All in all, a lot of rambling over way too much information. Those are my basic observations, I wish I'd done things more scientifically though, I might try splitting my newt larva up when they hatch and raising them differently.
Anyhow, sorry about the long meaningless post, kinda a slow night and I'm a bit hopped up on pain-killers from having my wisdom teeth removed.
