Zigzag rail fences are often seen in this ranching/forest area - some are quite old and others new. They are very labor intensive which is one reason we've never done one ourselves. I'm sure there are many ways of building these fences but I'll tell you what I know. At the bottom of each corner ranchers put either a chunk sliced off a log or a large flat stone to keep the rails off the ground so they don't rot too quickly. I've heard some people also drill a vertical hole thru the rails/logs at each 'corner' and place a rebar to hold the rails together. There is a way to build a 'gate' (which is not really a gate, as such) for people but which cattle and horses cannot get thru altho it's not easy to describe and I cannot find a pic online w/a quick search. What is done is that the fence is constructed so the person has to walk in a 'V' alley which is fairly narrow. Cattle and horses do not have space to do the same and will not walk where they cannot see a clear path. Maybe someone else can describe this better. It may not be what you need as it won't keep people or small animals out. Wherever you need access to this garden you could overlap the fencing leaving a space for people to walk. The rebar idea would help keep the fence together at those ends. I think it's the mass of the log rails that will keep it secure. Wouldn't be easy to push over. If you do need a proper gate for security you could use a couple of posts in those areas and hang the gate on them. Use spikes to connect the rails to the posts in those areas (or wire them together) otherwise the posts won't stay vertical. Some physics involved in fence building when it comes to dealing with the stress at corners and gates. I haven't read this site but there are pics showing this type of fence. Here is a link that might be useful: stack rail fence

I just finished emptying my big compost bin and found that in the very middle, where the compost was completely digested, there were no worms; around the outside, where there was still some identifiable stuff, there were tons of worms. So, perhaps your compost was completely done, and the worms headed off for more food? I have never heard of worm snakes. I have lots of brown snakes (that's their name, not just a description), and maybe they eat worms, but they are rarely in the compost. Some of the worms in the compost are 6 to 8 inches long, fat, and can move like lightning - maybe you have ubercompost worms.

Rose slugs, the larva of a sawfly. Control is with hand squishing, Insecticidal Soaps, Neem oil in that order. I had them on my roses until I got the soil into a good, healthy state so the roses that grew there were strong and healthy and I've not seen them on the roses for several years. I have had them in the past on the Hibiscus, but not this year.

Without knowing your location, I'll go out on a limb with Pine Sawfly larvae (Diprion similis)?