Protocol for Arthropod Pitfall Sample Analysis

(10/25/01)

1.      A minimum of 9 pitfall traps should be established at each mammal-trapping locality (not each web). Pitfall traps should be left open continuously and samples should be collected during the same period as the monthly mammal sampling. The entire contents of the pitfall trap should be rinsed into a jar with a label (100 % cotton rag paper and permanent ink) containing the site, pitfall number, and date. 

2.      Once back from the field, the contents of each jar should be rinsed and all dirt and debris removed.

3.      (Optional for CSU, MT, and Yavapai) Based on the attached list of likely food source arthropods for Peromyscus, separate each pitfall sample into two groups: (a) Food Source Arthropods and (b) Non Food Source Arthropods.  Each of these groups is to be vialed and labeled separately in 32-ml, Wheaton, snap-cap (or similar) vials.

4.      For Food Source Arthropods and Non Food Source Arthropods separate specimens into categories by order as listed on the attached Arthropod Data Sheet. Taxa not listed on the data sheet should be listed under other.

5.      Count and weigh the specimens in each taxon and record values in the appropriate location on the data sheet and in an MS Excel spreadsheet. 

6.      Note any orders that do not contain taxa as 0 in the spreadsheet instead of leaving blank.

7.      Flying arthropods from all orders should be lumped in one group and not included in the totals, as pitfalls cannot accurately sample flying species. However, it is desirable to know when there is an influx of some species (e.g., moths, cicadas), so count, weigh, and note dominant species in sample.

8.      Weights for each order and the pitfall totals need to be taken at equal moisture levels.  The evaporation rate is quite high for 70% ETOH and weights will change quickly.  Samples should be kept wet until just prior to weighing. Total weights should be obtained by combining all samples and then reweighing, as opposed to simply adding the previous totals for each order. This will incorporate the weights of those orders that are <.01 g and did not register on the scale. The use of a drying oven to obtain dry weights would be ideal but would add time and complexity to the procedure. Since we are interested in the change through time, wet weights are sufficient as long as they are done consistently.

9.      All samples should then be returned to their labeled jars in 70% ETOH and archived as voucher specimens for future use or reference. As a final step, an alcoholic voucher collection should be prepared, consisting of one member of each taxon with an identification label.

Food Source Arthropods for Peromyscus

• Amblypygi  (Tailless Whipscorpions)
• Araneae  (Spiders)
• Chilopoda  (Centipedes)
• Coleoptera  (Beetles)
• Dermaptera  (Earwigs)
• Dictyoptera  (Cockroaches and Mantids)
• Diplopoda  (Millipedes)
• Diplura  (Diplurans)
• Hemiptera  (True Bugs)
• Cicadidae larvae  (Cicadas)
• Isopoda  (Sowbugs)
• Isoptera excluding males (Termites)
• Lepidoptera larvae  (Caterpillars)
• Opiliones  (Harvestmen)
• Orthoptera  (Grasshoppers, Crickets, Katydids)
• Phasmida  (Walking Sticks)
• Scorpionida (Scorpions)
• Solpugida  (Windscorpions)
• Thysanura (Bristletails)
• Uropygi (Vinegarones)

  Non Food Source Arthropods and those not accurately sampled by pitfalls.

• Collembola  (Springtails)
• Diptera  (Flies)
• Homoptera, adults  (Cicadas/Leaf Hoppers)
• Hymenoptera  (Ants, Bees, Wasps)
• Lepidoptera adults  (Butterflies and Moths)
• Neuroptera  (Lacewings, Antlions)
• Any taxa which are 5mm or less in body length.