Some thoughts for those of you planning to leave larger cups in the field for an extended period of time:
I am using elevated 16 oz cups filled with liquid, and based on Sam's findings, filled close to the top with liquid. I am changing these on a weekly basis. I have been thinking about putting slits or holes near the tops of the cups to act as drainage if the cups receive any additional liquid (rainfall). I am concerned with liquid overflowing because it could carry any floating insects with it and out of the cup. I am not so concerned with rainfall diluting the liquid, and in any case don't have ideas to prevent this.
If anyone has additional comments or ideas dealing with overflow, please let me know.
--- In email@example.com, Sam Droege <sdroege@...> wrote:
> I have been running a series of small bowl experiments looking at a number
> of properties of bowls. Looking back on the many such experiments I have
> run, it seems to me unlikely I am ever going to actually publish most of
> these, however, it seems useful if I can somehow back up the statements I
> make about bowl preferences via some form of public access to the original
> Consequently, I am documenting these small investigations on a blog:
> Feel free to comment, rerun analyses, etc.
> I would also be more than happy to include your bowl experiments here in
> what hopefully will be a repository of lost data.
> Conclusions from the latest round of experiments are that for the spring
> vernal woodland bees tested (results on the blog above) ....
> 1. Equal capture rates are obtained using soapy glycol or soapy water
> 2. Large white plastic drinking cups catch as many bees as the 3.24 white
> solo bowls as long as the large cup is full of fluid (within a few mm of
> the top of the cup).
> 3. Large white plastic drinking cups half full of fluid capture only
> about half as many bees
> 4. Styrofoam bowls or cups of any shape essentially do not capture bees
> Some other observations.
> 1. Glycol solutions seemed to dissolve the paint off of Styrofoam
> cups....will see if this happens to plastic ones....it doesn't appear to
> be the case with Dave Smith's western traps which I think were spray
> 2. Adding a 2 tablespoons of household bleach to a gallon of Walmart Red
> RV Propylene Glycol solution removes all the red by the end of the day
> (after recapping and shaking).
> 3. There are 3 main sources of Propylene Glycol
> A. Swimming pool supply houses
> B. Walmart (rv supplies)
> C. RV supply stores
> D. Secondarily heating and cooling supply places can have glycol,
> but usually have to special order and it is often blue ...and may be a
> different concentration.
> E. Note that it is much harder to find PG in the spring because
> it use primarily to winterize things....
> 4. It is important to add detergent to the glycol to get rid of the
> surface tension.
> 5. The literature indicates that dilutions of up to 20% work fine for
> trapping solutions (preserving)
> 6. Our eat-all-sorts-of-disgusting-things-cur-dog completely ignored cups
> of glycol scattered throughout our yard...and soap and glycol solutions
> seemed equally prone to disturbance in the woods (our teenagers also
> ignored them).
> 7. Denatonium Benzoate (a.k.a. - the world's most bitter substance) can
> be added to glycol to make it unpalatable to anything alive (20-40 ppm).
> It is required in ethylene glycol (antifreeze) mixes in some states. It
> can be ordered under the trade name Bitterex but we found a place in
> Bowie, Maryland that also carries this uncommon compound (no experiments
> yet on if it changes capture rates). Side story: I received a small
> batch of this double wrapped in bags. There was no sign of any powder or
> residue on those bags....and I didn't think about it until I noticed that
> my green tea tasted absolutely awful, and that when I licked my upper lip
> it also tasted terrible (I thought...now that is bad tea it even made my
> lips taste bad), and the apple I ate was similarly terrible....and then I
> realized it...D. B. is truly the most bitter compound in the world as
> there must have been just a slight amount on the package which got on my
> face and then ruined my taste buds. MSDS sheet implies it is harmful in
> large doses but otherwise not a big deal...but I can't image what a small
> dose of this would do. It is also used to denature alcohols...
> Some implications for trapping
> Dave Smith of FWS evolved the basic design (read about it in the handy bee
> manual) for a long-term trapping system using glycol, stadium cups, and a
> simple home made stand (someone recently told me this as a classic LA
> solution....when asked what LA stood for he said "Lower Arkansas." I then
> realized my entire operation was LA and will now where that appellation
> with a badge with honor). So these above tests were to designed to see
> how Dave's system directly compared to the standard soapy bowl
> formulation....and it seems to be quite comparable with the exception that
> cups need to be kept full. Since glycol only evaporates slowly that
> shouldn't be difficult and if you start with a 50% dilution then further
> dilution by rain should still yield well preserved specimens. Be it noted
> that white 12 ounce plastic drinking cups are commonly available on the
> web and in Party Stores. We have made a stand similar to Dave's using
> gray half inch plastic electrical conduit as a post and 1/2 inch cut rings
> of white pvc 3 inch drain/waste/vent pipe which are screwed to the
> conduit. Dave has rocky soil and so uses rebar to run up the pipe but we
> have clay soil and just hammer the pipe into the ground.
> Sam Droege sdroege@...
> w 301-497-5840 h 301-390-7759 fax 301-497-5624
> USGS Patuxent Wildlife Research Center
> BARC-EAST, BLDG 308, RM 124 10300 Balt. Ave., Beltsville, MD 20705
> A Lecture on Aphids
> She plucks my sleeve.
> "Young man," she says, "you need to spray.
> You have aphids on your roses."
> In a dark serge coat and a pill box hat
> by god it's my third grade Sunday school teacher,
> shrunken but still stern, the town's
> most successful corporate attorney's mother.
> She doesn't remember me. I holster
> my secateurs, smile publicly,
> and reply, "Ma'am,
> did you know a female aphid is born
> carrying fertile eggs? Come look.
> There may be five or six generations
> cheek by jowl on this "Peace" bud.
> Don't they remind you
> of refugees
> crowding the deck of a tramp steamer?
> Look through my hand lens-
> they're translucent. You can see their dark innards
> like kidneys in aspic.
> Yes, ma'am, they are full-time inebriates,
> and unashamed of their nakedness.
> But isn't there something wild and uplifting
> about their complete indifference to the human prospect?"
> And then I do something wicked. "Ma'am," I say,
> "I love aphids!" And I squeeze
> a few dozen from the nearest bud
> and eat them.
> After the old woman scuttles away
> I feel ill
> and sit down to consider
> what comes next. You see,
> aren't sweet
> as I had always imagined.
> Even though rose wine is their only food,
> are bitter.
> - Charles Goodrich
> P Bees are not optional.