What the heck are these?

Does anyone know what these are???  They have invaded our yard:

I would love to know if they are harmful to the trees in our yard or harmful to my plants.

Promising growth

I'm excited about the things that are starting to change and grow in the garden!

Does anyone have experience with growing raspberries?  When will the flowers produce fruit?  Will I need to cover it with a net to keep the birds from getting it? 

To spray or Not to spray?

I have been doing a lot of reading about insecticides lately.  I use only organic ones, but I've read that if you let your garden 'settle' for a while without any insecticides it will eventually self-regulate.  Since insecticides kill both the unwanted bugs and the beneficial bugs, over time the beneficial bugs build up to the point where they are taking care of the unwanted bugs.  In order for that to work, though, you have to have optimal garden conditions.

I'm wondering if anyone out there has actually let their garden self-regulate and had it work?  Any comments on how/when you use insecticides?  Any suggestions would be great...