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754New pan trap design for arid dry climates

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  • David_r_smith@fws.gov
    Sep 14, 2009

    Hi All,

    Sam Droege wanted me to pass this on to you:

    New Pan Trap Design for Arid, Low Humid Regions

    As part of a native pollinator inventory, I have been looking for a reliable pan trap method.  I initially used two-ounce painted Solo cups with soapy water at five sites along an elevational gradient north of Flagstaff, Arizona.  In order to increase the opportunity to sample a higher diversity of species, I decided to leave the traps out for a week. I substituted recreational vehicle antifreeze-grade propylene glycol in 12 ounce plastic bowls since it was obvious soapy water would not last long enough.  Unfortunately, summer temperatures and low humidity caused the bowls to dry up and blow away before a week had expired (I can make someone a killer deal on a couple thousand 12 ounce plastic bowls).

    I changed from 12 ounce bowls to 12 ounce heavy plastic “stadium cups”.  These ar ethe cups you see given to kids off the kids menu at many resturants.  Each cup, painted either fluorescent blue or yellow, or left white is attached to one-half inch PVC pipe with a five-inch hoop cut from a plastic culvert pipe (see photo).  The stadium cups are very sturdy and are likely to hold up for a long season or two (or three) of sampling. The hoop is attached to the PVC pipe with a bolt and lock nut.  The pipe slips over a piece of rebar set into the ground.  The hoop is set high enough so the cup rests about three inches above the ground. If desired, a trap number can be written on the white plastic hoop.  In order not to confuse the issue by having insects attracted to the white PVC end up in the blue or yellow cup, I painted the tops of holders the appropriate color for the cup it would hold.  The top of the pipe is plugged to prevent bees from crawling down inside and getting trapped. The cups, filled halfway with the 50% industrial grade propylene glycol (50 Water:50 propylene glycol) easily lasts for a week.  The cups do not sit on the hot ground (air passes under them) and deeper cup lip and deeper fluid level slows down evaporation.  I remove the cup from the hoop and dump the sample into a sieve.  Leftover propylene glycol is collected in a bucket when the sample is poured through the sieve. The sieve is dumped into a plastic jar with alcohol.  I use a funnel used when you add oil to your car (the opening is large enough not to get clogged with the sample, I get a lot of big Tachinids) to dump the sample finally into a labeled Whirl-Pak.  Funnels with wide opening can be found at Auto Parts Stores. I also find that collecting samples goes much faster if the labels are pre-cut and placed in the Whirl-Pak beforehand.

    Dave Smith
    U.S. Fish and Wildlife Service
    323 N. Leroux St., Suite 101
    Flagstaff, AZ  86001
    (928) 226-0614 x 109
    "Field data is the best cure for a precarious prediction"  Dave Rosgen

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