JB Sampling Methods

Step 5: Sampling Eggs and Grubs

Materials

  • LabQuest2 and/or field notebook
  • Ruler/Measuring Tape
  • Sheets of Paper/Plastic/Cloth (to put soil on temporarily)
  • Hand Shovel
  • Paper Towels
  • Images of Japanese Beetle Grubs For Visual Identification
  • Digital Camera

 

Methods:  Recording Japanese Beetle Grub Count and Lengths Manually in LabQuest2

--To access the Japanese Beetle table, tap on “File” (top of screen) and highlight open.  From the file list, highlight JB Grubs and open the file. 

--Before you begin collecting your grub data, save your own version of the table.  Tap on “File,” highlight “Save,” and tap on the title window.  A keypad will pop up and you can title your file: firstinitiallastnamejbgrubs (e.g. ljonesjbgrubs).  Tap on “Done” and “Save.”

--After counting the number of grubs present a certain depth at a sample point, tap on the cell in the table which corresponds to the depth, plot, and sample point at which you counted the grubs.  Enter the number of grubs in the cell.

--For each grub you find, record the length on the notes page of the file.  Highlight the notes icon (upper left of screen), Tap on the screen next to the plot and sample point where you need to enter lengths and type the measurements (report your measurements in cm).

Note: If you are unable to access or create a table on the LabQuest2 unit, record the number and lengths of the grubs you observe in a field notebook.

Methods:  Japanese Beetle Eggs and Grubs 

--As you took your soil temperature and soil moisture readings, you were preparing for the JB eggs and grub sampling process.  The sheets on which you placed the soil you removed during the sampling process will now serve as your JB eggs and grub collection surface.

--At the first sample point in your plot, to a depth of 5 cm, remove a 15 cm x 15 cm square core of soil (widen your soil moisture hole and add the additional soil to the sheet holding the 5 cm pile).  If you widened your hole during soil temperature and soil moisture data collection, proceed to the next step.

Excavation process

 

Excavation process: Photo courtesy of Kohen Joiner, ENVS student, ESC

 

--Gently examine the soil for JB eggs.  Eggs will be small and white, and they typically appear in masses. 

--If you observe JB eggs, use the following grids to determine the percentage coverage of the eggs.  Compare the amount of soil covered by Japanese beetle eggs to the amount of space in the grid covered by grey color in the images below.

 

 

Beetle Egg Coverage Grid            JB Eggs Grid

JB Eggs Grid             JB Eggs Grid

 

--Gently separate the soil particles and count any grubs you observe.  Grubs will be white in color—see images at the USDA website (or other extension website) as reference for identification:  http://www.aphis.usda.gov/lpa/pubs/pub_phjbeetle04.pdf.   

beetle grub

Beetle grub: Photo courtesy of Brad Saville, ENVS student, ESC

--Record the number of grubs in your JB Grubs table in LabQuest2.  Note the lengths of the grubs you observe on the notes page.

--Save your file before moving to your next depth.  Tap on “File,” highlight “Save,” and highlight the name of your JB Grubs file.  Tap “Save” and “Overwrite File.”

 

Tip:  Don’t forget to take pictures of your sampling process, study site, and grubs found.  Reports are better with illustrations demonstrating your process and findings.

 

--Next, remove the next layer of soil from your sampling point (if you have not already done so).  Remove a 15 cm x 15 cm square of soil to a depth of 10 cm (widen your soil moisture hole and add the additional soil to the sheet holding the 10 cm pile). Gently separate the soil particles and count any grubs you observe. 

--Record the number of grubs in your JB Grubs table in LabQuest2.  Note the lengths of the grubs you observe on the notes page.

--Save your file before moving to your next depth.  Tap on “File,” highlight “Save,” and highlight the name of your JB Grubs file.  Tap “Save” and “Overwrite File.”

 Excavation process

Hunting for grubs: Photo courtesy of Allan Varcoe, ENVS student, ESC

-- Next, remove the next layer of soil from your sampling point (if you have not already done so).  Remove a 15 cm x 15 cm square of soil to a depth of 20 cm (widen your soil moisture hole and add the additional soil to the sheet holding the 20 cm pile).  Gently separate the soil particles and count any grubs you observe. 

--Record the number of grubs in your JB Grubs table in LabQuest2.  Note the lengths of the grubs you observe on the notes page.

--Save your file before moving to your next depth.  Tap on “File,” highlight “Save,” and highlight the name of your JB Grubs file.  Tap “Save” and “Overwrite File.”

 

-- Next, remove the final layer of soil from your sampling point (if you have not already done so).  Remove a 15 cm x 15 cm square of soil to a depth of 30 cm (widen your soil moisture hole and add the additional soil to the sheet holding the 20 cm pile).  Gently separate the soil particles and count any grubs you observe. 

--Record the number of grubs in your JB Grubs table in LabQuest2.  Note the lengths of the grubs you observe on the notes page.

--Save your file before moving to your next depth.  Tap on “File,” highlight “Save,” and highlight the name of your JB Grubs file.  Tap “Save” and “Overwrite File.”

--Return the soil layers to the hole (minimize environmental impact).