Time of Day Sampling and Stink Bugs

This is some old data from 2007 but it is still relevant today. How does time of day effect stink bug populations? When this small test was conducted we did not have redbanded stink bugs in our system but I would be surprised if the they did not follow a very similar trend.

A question we often get is how much late season temperatures affect the numbers of stink bugs we catch at different times of day.  We know that early morning is the coolest part of the day and it is not uncommon to see stink bugs basking on the leaves in the morning hours.  As the temperature increases stink bugs move down in the canopy.  This often results in counts that are higher in the mornings than mid day and afternoon but the stink bugs are still in the field.  We did a small experiment in 2007 to try and understand just how much of a difference it can make in numbers caught in a sweep net.  Below are the results.  We had four people each take 4 sets of 25 sweeps in the same field at 8 a.m., 1 p.m. and 5 p.m.  for a total of 400 sweeps at each time interval.  At the 8 a.m. sample time the air temperature was 75 deg. F., and at 1 and 5 the air temperature was 94 deg F.  The results indicate that later in the day stink bugs are moving down in the canopy making the efficiency of the sweep net less for mid and afternoon samples.  This is not unexpected but does indicate that if you are very near threshold later in the day, you probably are at threshold.  We also monitored bean leaf beetle, three cornered alfalfa hoppers, and green cloverworm.  None of these other species seemed to be affected by the temperatures and counts were similar for each sample period.  Keep in mind that this is only one field at one point in the season for southern green stink bug.  The red line on the graphs is threshold. Although we did not test this, a drop cloth may provide more consistent results. We plan to study this in more depth next year.