Late summer and fall picnics can be ruined by the presence of stinging insects , mostly yellow jackets, which are attracted by sweet foods placed out on the table. However, the problem can be remedied with the use of inexpensive store bought or even free home made yellow jacket traps.

If you wish to buy a trap, an online consumer website http://www.galttech.com/research/household-DIY-tools/yellow-jacket-traps.php recommends  RESCUE Reusable Yellow Jacket Trap . The traps are inexpensive, ($10.00), and reusable. If you run out of bait you can substitute something sweet like sugar water or crushed fruit or soft drink.  A second choice is Raid Disposable Yellow Jacket Trap (81605) - 4 Pack:. These traps cost around $35.00. However, the advantage is that they are disposable, and avoid the need to clean and reuse.   A third recommendation is Glass Yellow Jacket & Wasp Trap: by Greenfleet . These traps go for around $20.00 they are reusable, decorative and attract wasps as well as yellow jackets. 

If you prefer, you can build a very effective yellow jacket trap, in a few minutes at no cost at all. The only supplies you will need are an empty 2 liter plastic bottle, some tape or staples, some string and a kitchen knife or hole puncher. Just follow the instructions.

1. Take an empty 2 liter plastic bottle; a mineral water bottle will do just fine.
2. Cut the top off, just where the diameter has become as wide as the body.
3. Fill the empty bottle base partially full of bait.          
4. Yellow jackets like protein  in the spring, when they are mating, so if it's springtime you will use a chunk of meat.     
5. If it's late summer, when yellow jackets are most aggressive, use something sweet, like fruit chunks. They love mashed up grapes or banana. Other bait choices include a 1/2 cup of sugar and 1/2 cup of water mixture, 1 cup of apple cider vinegar, I banana peel, half fill bottle, lemonade or even Pepsi/soda. You can use anything you have seen yellow jackets attracted to at one of your outdoor picnics.       
6. To add to the killing power of the trap, squirt in a couple of tablespoons of dish washing liquid        
7. A  little bit of yellow food coloring can also be added as the color yellow attracts them.
8. Now invert the top of the plastic bottle, upside down, so that it resembles a funnel, and place it inside the lower half of the bottle, remember to remove the plastic top.
9. It should hold in place, depending on the bottle shape
10. Tape and/or staple the top together with the bottom of the bottle. Make sure the seal is tight.
11. Cut two holes in the plastic where the two pieces come together, near the top. Put string through the holes and use to hang the bottle.
12. Use a slippery substance such as hot soapy water, dishwashing soap or Vaseline and spread it along the exposed surface of the funnel. This will cause the yellow jackets to lose their footing and fall into the trap. Cooking oil may also be used.
13. Place about 20 feet from the picnic table
14. Works best at a height of four feet
15. Works best at around 85 degrees
16. The yellow jackets will fly in, attracted to the sweet. When they try and leave, insect  logic dictates they should look for the highest point to exit. They will fly around, but miss the inverted opening. When they get tired they will fall into the soapy liquid. The soapy liquid, will stick to the yellow jacket body making it impossible for them to breath. 
17. When full replace the trap with a new one or empty the trap regularly making sure the yellow jackets are dead. You can kill the yellow jackets by filling the bottle full of water, or covering it with plastic and placing it in the freezer until they freeze to death.
18. Replenish the bait every few days.
19. DON'T let live yellow jackets escape. Their frenzied distress in the trap will attract nearby yellow jackets, and the idea is to keep them all in the trap.  DON'T crush yellow jacket bodies as that emits a smell warning yellow jackets to attack. You can also free the yellow jackets in the wild, however they may return  
20. Bury dead yellow jackets or flush them down the toilet as dead yellow jackets emit a warning odor to living yellowjackets .