Insect Barrier Tunnels
Last year, I grew broccoli and cauliflower under insect barrier cloth help up with arched PVC pipes and tightly held down to the ground along the hems with great success. (I also grew cabbages under an insect barrier low tunnel in previous year)
Subject: Yay! Got some planting done!
These are easy because excluding pollinating insects is not an issue.
This year, I tried a medium tunnel (almost 4 ft high x approx 5 ft wide x 10 ft long) supported with PVC arches to grow winter squash that are susceptible to SVB (squash vine borer) and it was a great success in terms of protecting from SVB's, Squash Bugs, and Stink Bugs. I still don't see any sign of infestation.
The size of the tunnel accommodated smaller fruiting (max 10 Lbs range) squash, but I think larger squash vines would have been pushing it. When they were at their most robust, the leaves were pushing on the sides as well as top of the tunnel.
One big minus is that you do have to get in there and hand pollinate. (In fact I have found that even outside of the tunnel, there was more success rate when I hand pollinated winter squash and watermelons). I was diligent at first but as it got hotter and the gardening chores increased, it became harder. When they were lush, it was difficult to get everybody back under and close the tunnel. I often saw female buds that would open THE NEXT DAY and then didn't get out to the garden or didn't get to opening the tunnel and pollinating. VERY often discovered femal blossoms that opened the previous day -- too late to pollinate.
I also lost three very nice squash fruits when I didn't realize they were ripe/mature enough to pick. I had grown early maturing varieties, and I think in the heat and humidity they matured faster than expected, and then was susceptible to becoming overripe and spoiling when I didn't get out in the garden for multiple best wave days. They had completely softened and fermented/rotted by the time I discovered them. The fact that they were new-to-me varieties didn't help.
For fall growing, I'm using a picnic table tent for protecting food from bugs to grow some cabbage and kale starts. I know from past experience that without the protection, they would be almost immediately covered with cabbage moth and cabbage butterfly worms and dessimated.
...so far, one Armyworm snuck in, and I think there's a slug. But enough survivors and significantly reduced damage/loss. I did lose a bunch of earlier seedlings to damping off when I failed to empty the catch trays after a heavy rain for 24 hours.
(I'll come back and embed applicable thread links for these at some point later -- I do have ongoing threads -with lots of pictures

- for all of these experiments/projects.)
--- initial insect barrier tunnel used for the planted out squash seedlings is pictured in this thread here:
Subject: 2014 pre-germinating/sprouting experiment Peas, Corn, Curcs applestar wrote:Some of the protected C. pepo and C. maxima squash progress
...and here
Subject: 2014 Spiral Garden Garlic Onion Pea Corn Squash Cuke Beet
applestar wrote:Winter squash that are susceptible to SVB's were planted in the Haybale Row. They were C. pepo Bush Delicata and Kakai, and C. maxima Uncle David's Dessert, Red Kuri, and Guatemalan Blue. I covered them with this insect netting row cover
--- picnic table tent is pictured and described here:
Subject: Protecting summer cabbage/broccoli/kale seedlings for fall