They call it pine straw and sell it in large quantities in the south. I haven't seen it offered for sale in PA. If the hill is badly eroding you might need something better than pine straw to keep it in place. How bad is the erosion?

Our local Agway store sell pine needle straw in large bales. Check your local garden store or nursery, if they don't have it I am sure they can tell you where to buy it. I use it every year for certain beds.

I don't know where one would buy it, but we make our own. My husband runs over the pine needs and cones with a lawnmower to chop them. Then we scoop them up and use them around flowers. Great for rhododendrons and azaleas, most other things. It decomposes more slowly, retains moisture better and deters some bugs.

I'm interested too. Our local agway in Connellsville Pa doesn't carry it. They told me to try Southern states in Morgantown WV. I have yet to contact them about it, I'll do so Monday. This would benefit the Original poster too, I am close too Pittsburgh so it isn't far for them to Morgantown either.

I called today and they don't sell it at the Morgantown wv southern states. If you have the resources to pay a good bit you can get a tractor trailer load from southern companies Pine straw direct is one of them, hope I got the name right. More than likely you don't want that much. I have been getting mine at the leaf collection for our township and it's rare that you see pine needles ( mostly leaves )I collect the leaves too. I put some shredded leaves under wood chip mulch to help stretch the wood mulch a bit because I have alot of mulching to replenish each year.You may be too late for the collection of the needles for this year, there is a window of Oct - November when the most is dumped at the compost site. I used every bit I got right away.

I got my pine needle mulch from Cedar Run Landscapes. They are located outside of Philadelphia.

Here is a link that might be useful: Philadelphia Pine Needle Mulch Supplier