Thursday, August 11, 2011

Building a pecan weevil trap

    Knowing when to spray for pecan weevil is the first step towards controlling the number one insect pest of pecans. "Circle" pecan weevil traps have proven to be the best method for determining when pecan weevil adults are emerging from the soil.
    In this post I'll be giving step-by-step instruction for building a weevil trap. Before starting you will need to gather the following tools and supplies.

     Metal shears
     Heavy duty staple gun
     Book binder's stapler
     Hot glue gun

     Aluminum screen wire, 36 inches wide
     Wood strips, 1.5 inches wide and 0.5 inches thick
     1/2 and 3/8 inch staples for staple gun
     1/4 inch staples for book binder's stapler
      Deck screws  (3 inches long)
      10 gauge wire
      glue sticks
      Boll weevil trap top assembly (order here)

Step 1. Measure out 24 inches of screen wire and cut with shears.

Step 2. Fold screen wire in half (length wise). Press on the fold just enough to mark the center of the screen.

Step 3. Use a round object (8.5 to 9 inches diameter) to help trace a semi-circle at the marked half way point on the screen wire.

Step 4. Use the tip of the shear to trace the semi-circle onto the screen wire.

Step 5. Use the shear to cut out the semi-circle.

Step 6. Fold over the screen wire along the edge of the semi-circle to form a smooth edge.

Step 7. Place a 17 inch piece of wood strip down the middle of the screen wire. Fold the screen wire over twice along the bottom to make a smooth strong edge.

Step 8. Flip the screen wire over and staple the screen to the wood strip using 3/8 inch staples. The first staple should be placed 2 inches down from the semi-circle. Continue stapling down the wood strip every 2 inches until you get to the bottom of the wood strip

Step 9. Attach an 11 inch strip of wood along the upper edge of the screen wire, again staring 2 inches below the semi circle.

Step 10. Clamp a 30 inch long piece of 2x4 into a bench vise at a slight upward angle from horizontal. Place the long wood strip on top of the 2x4 and slip a boll weevil trap top under the screen wire.

Step 11. Staple trough the screen wire and boll weevil trap into the wood strap using a 1/2 inch staple. Use a hammer to make sure the staple is driven in tightly.

Step 12. Turn the trap over, wrapping the screen wire over the boll weevil trap top and place the short wood strip on the 2x4. Pull the screen tight, setting the trap top on top of the wood strip but under the screen wire. Staple in place with a 1/2 inch staple.

Step 13. Wrap the other side of the screen around the trap top then staple at the top with another 1/2 inch staple.

Step 14. Firmly attach the rest of the screen wire along the short wood strip using 3/8 inch staples. You should now have a cone shaped trap with a boll weevil trap top at the apex.

Step 15. Along the outer edge of the trap (the edge that hasn't been folded over yet), fold the screen wire over about 1.5 inches. As you make the fold, tuck the fold under the short wood strip.

Step 16. Cut a 36 inch piece of 10 gauge wire to place under the fold on the outer edge of the trap.

Step 17. Use the book binder's stapler to hold the wire inside the fold of the screen wire.

Step 18. Crimp the screen wire tightly around the boll weevil trap top. Fill in any gaps between the screen wire and trap top with hot glue.

Step 19. Use a standard No. 2 pencil to widen the hole in the top of the boll weevil  trap top. (pecan weevils are larger than boll weevils)

Step 20. Install the plastic cylinder and perforated top to the boll weevil trap top assembly.

Step 21. Install your new pecan weevil trap on a tree with a history of weevil problems. Scrape the rough bark off the tree at the point of trap installation. Use 2 deck screws to attach the long wood strip to the tree. Stretch out the screen wire across the bottom of the trap and staple to the tree using 1/2 inch staples.

Monitoring Traps

     Install traps by the 1st of August. Check traps at least 3 times per week. If you capture an average of 2 weevils per trap it is time to spray for pecan weevil. Continue to monitor traps after applying the first insecticide treatment. If weevils continue to emerge, wait at least 10 days before making a second insecticide application.