First Collection Prep: Pitfalls and Sticky Traps

18 April 2017

Today we finally got the experiment completely set up and collected some plant herbivory data. Soon we will have initial data for all of our response variables! It was a great day for field work. The sun was shining and it was a pleasant temperature, not too hot and not too cold.


To tackle all of the field work we had on our plate, we decided to split into groups. Our six plant grading experts went in pairs to each field site to evaluate herbivory and measure plant height, leaf number and leaf area. The damage to the brassica was found to be less extensive than we initially thought and the riparian tomatoes were doing great; however, a large number of the basin and grassland tomato plants were withered and dying.


Robert and John went around to each block to empty each pitfall trap of bug soup and collected the arachnids from the predator removal cages. We had a few lizard casualties, but we were able to save a few. Hopefully our new non-lethal pitfall method will work to minimize unintended insect and lizard deaths in the future. They then lethalized the traps with our soap and water mixture.


The rest of us went around to each block to tie on the sticky traps. We tied them on the west side of the cages parallel with the reflectors with the sticky side facing in. It was sticky work, but luckily Louie came in clutch with the mineral oil at the end.


After setting up the cages we decided to test the lights at each block. We were able to verify the lights at the grassland and riparian blocks, but the lights at the basin block failed to turn on. Marshall took the battery to the lab to charge and went back in the evening to investigate the wiring and was able to fix the problem. He also took some awesome nighttime photos in the process.


^It took a bit of finagling to block out enough light for the riparian lights to turn on.

(Photo credit Marshall McMunn) The lights look nice and bright and the reflectors appear to be reflecting well.

At the end of the day we decided to have a nice discussion by the Riparian block instead of driving back to the lab room. We addressed all kinds of issues involving plants, sampling, predator removal and messaging apps. We capped off the day by going around and talking about our stress levels and how we were feeling about the experiment.

Some of the points covered and plans made in our discussion:

  • During predator removal we should only remove arachnids
  • Because cohort 1 was in the ground for a week before insect data was being collected, we decided to plant a cohort 3 as soon as possible to get enough insect data rather than have cohort 1 in the ground for 3 weeks. We will end up with one week of insect data from cohort 1, 2 weeks of data from cohort 2 and 1 (possibly 2) weeks of data from cohort 3. We will replace the cohorts every 2 weeks.
  • We discussed the possibility of leaving cohort 3 out for 2 weeks resulting in a total of 5 weeks of insect data. We decided we will wait until we start analyzing data later on to see if it’s worth it or not.
  • As some studies counted them, we discussed the possibility of adding seedpod number to the plant checklist, but decided against it.
  • There were concerns about the value of data from the wilted tomatoes from the basin and grassland blocks and we discussed replacing them with peas, however, an extra pea would be a sub-sample and not a true replicate and could exhibit some other confounding effects. As such, we decided to stay the course and continue planting our three plants.
  • To prevent unintentional casualties during non-collection days, we decided to fill up the non predator removal pitfall trips with grass to make it more likely for insects and lizards to escape. We will continue filling predator removal pitfalls with an inch or two of hay to minimize predation within the pitfall.
  • Many of the pitfall traps were not flush with the ground and it was recommended we bring a tool out to the field to clear out the dirt underneath them on collection preparation days.
  • We decided at one point when we have time that we should quantify the weeds around the treatments.
  • At some point we should also do a survey of the web spiders on the cages.
  • A lot of people like the ease of discussion on Groupme and the announcement function of Remind; we will continue using these two messaging services.
  • We discussed the importance of face-to-face meetings with the whole class and talked about prioritizing them whenever possible. We discussed arranging video meetings on weekends if we aren’t able to have an in-person discussion that week.
  • Getting aerial footage of the blocks at night should be done when we have the time.
  • It was great discussing how we felt about the class and what was stressing us out.

Plans and points for later on this week:

We still don’t know for sure what sampling technique we will use for the sticky traps on Thursday (depending on weather, insect abundance etc.), but there are a few things we can do to prepare in the meantime:

Wednesday (4/19/2017):

  • Take pictures of sticky traps to help give us some idea of the amount of insects there will be on Thursday. (Predator removal/solar panel movement team)
  • Put tape on 90 nalgene bottles in preparation for labeling the collected pitfall traps on Thursday (I can do this around 2pm)
  • Prepare sieves for collecting pitfall traps. Marshall mentioned he had 2 and can fashion (get?) another (Marshall)
  • Bring folding tables to lab for transport to the field on Thursday (Could be brought directly on Thursday instead?) (Marshall and Louie)
  • Not critical at this time, but we could always use some fishing line and sticky trap tying when people are able.
  • Print out sticky trap data sheets.

Because it is not clear what the insect abundance will be on the sticky traps, we have a number of strategies planned for Thursday that we can choose on the spot.

Low insect abundance: 3 groups of two with one insect expert and one recorder. We determine insect order, tentative trophic level, length, and count for each sticky trap in the field.

Very high insect abundance/inclement weather: we fold the sticky traps up into a “teardrop” shape using tape or staples to hold them together and bring them back to the lab for identification.

Pitfall traps(any weather/abundance): 3 groups of two. Use sieve to drain the “bug soup” and transfer the insects into ethanol-filled nalgene bottles. Label the bottles with the cage ID.

Remove fishing line from cut sticky traps. Make pitfall traps flush with the ground.

Thursday (4/20/2017) weather as of early morning 4/19/17(temp: High 69F; clouds AM-sun afternoon; rain: 20-30% chance in the morning, 0% after 11AM; wind 5-10mph NNW):

  • We should go to the field early yet again, around 12-12:30pm.
  • Bring equipment from the lab to the field: Tables, stapler, tape, sharpies (pencils may be better because we’re working with ethanol), nalgene bottles, sieves, tulip bulb digger/other digging tool (for making pitfalls flush), scissors, data sheets, pencils, mineral oil and rag, hand lenses, rulers.
  • Collect sticky and pit fall traps. Remove excess fishing line. Dig out pitfalls
  • Meet up at the riparian block or the lab room for discussion.
  • Bring insects, data sheets, equipment back to the lab.


Also a big shout-out to Louie’s wife for coming out to bring us popsicles! Thanks, Tabatha!

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