Squash looked good, but did not produce

I have a problem and I know the good people at DG can help once again.
My yellow squash looked great, nice and green, full of flowers, I thought I would have a truckload of squash. Then the stems started to turn dry and brown and I only got 2 squash.
I started to pull up the real bad looking ones today and found some shells of what I thought are grub worms. The stems of the squash look like sawdust inside . I have a pic. of what these "shells" and the stems of the squash look like. What happened to my squash????????
Any info. would be greatly appreciated, as always.
Thanks so much
Mary

Squash vine borer

farmerdill,
Thanks for the reply, I was thinking vine borer. I have been reading some posts, some were yours, about this.
Are these just in the dirt or could I have brought them in with the mulch I used ???? Would sevin dust take care of them?
Mary

SVB is a tough customer. The culprit is a moth that imitates a wasp. They are strong flyers so there is not much you can do to get way from them. They come in flights and lay eggs on the stems of the squash, hatch out and immediately head down to the base of the plant and start tunneling in. Sevin ( liquid prefered as the dust is much more hazardous to bee) will work if you are sharp enough to catch the unhatched or hatching eggs. Once they get into the plant, Sevin is useless. It is a short lived contact poison so you have to get on the critters or their eggs to kill them.Sometimes it is possible, to schedule plantings so that you catch them between flights. There are a lot of tricks for dealing with SVB that you will see on this forum, but there is no foolproof chemical or organic solution available to the home gardener. Good sanitation does help, destroying the borer larva before they have a chance to pupate. It does cut down on future flights as they pupate in the ground. http://ohioline.osu.edu/hyg-fact/2000/2153.html