This morning I saw what looks like a spider. It has a green body about 1/2 inch long and has eight dark legs.
Many leaves of these (six) vines are turning yellow and have white splotches all over many of the leaves. I cannot find any other bugs. The plants are in a new 100% organic bed on the South side of my house.

What is the problem? Is this a spider and is it beneficial?

I suspect a disease. Did you use any compost under the vines?

Early this Summer I dumped the sludge from creating compost tea (after draining the liquid) on the ground around the gourds.

Since then, I have sprayed my home-brew version of Garret Juice plus Garlic Tea; this weekend, the white splotches were all over and I sprayed a new dose of Garlic Tea (commercial version mixed @ 4 oz per 1/2 gallon water)