Methods
V-FIT for weevils
M. Lourdes Chamorro
Research Entomologist, SEL, ARS, USDA, c/o National Museum of Natural History, Washington, DC, USA
Matthew L. Buffington
Research Entomologist, SEL, ARS, USDA, c/o National Museum of Natural History, Washington, DC, USA
In recent collecting expeditions to Panama in 2022, New Mexico, USA in 2023, and South Africa (currently) in 2023, we started to successfully use V-form Flight Intercept Traps (V-FIT) for the passive collecting of weevils (and other insects) that generally inhabit the mid- to lower areas of a habitat not regularly caught with any other method. This method is inexpensive and relatively easy to set up in the field.
The V-FIT was the brainchild of the Arizona-based entomologist Bill Warner (Warner 2017). The general idea is that of a Standard Vertical Netting Flight Intercept Trap (SVN-FIT) consisting of a semi-transparent panel placed perpendicular to ground pans filled with soapy water with the modification of replacing the vertical netting for two panels each angled 45 degrees outward from mid-line to form a “V”.
This method has been used successfully to collect rare and new species of Staphylinidae in Arizona (Lobl et al 2021) and Aphidiinae (Hymenoptera) from South Dakota (Martens & Johnson 2018).
We became interested in using Flight Intercept Traps, despite their tendency to be labor intensive, when we, Bruno de Medeiros, Matt Buffington, and Lourdes Chamorro, were in Panama in 2022 and came to the realization that many of the rare and new species of Dryophthorinae described by Bob Anderson (2002) were only known from samples collected by Steve Ashe, the late Staphylinidae worker, using FITs. We decided to give FIT’s a try. Buffington had already been using the V-Fit method in Patuxent, Maryland using the typical metal frame (Figure X) and this time we were going to try out the travel version without a metal frame but instead relying on rope to suspend the “V” transparent panels.
Warner (2017) and Lobl et al 2021 provide details on how to assemble the metal frame V-FIT and that is pictorially summarized here following our interpretation of the trap. We also provide some general information on both the metal frame and “travel” versions of the V-FIT and the materials we use, which may differ from original concept.
Materials shared by both set ups for a single trap:
Figure 1. xx
1. 4-5 trays (approximately 12 in long) – these will serve as catchment and the number of pans sufficient to span the width of the “V” sheeting;
2. Plastic sheeting (approximate dimensions 1.5 m (5 ft) by 2.4 m (8 ft) sheet of 0.1524 mm (6 mil), sometimes 0.1016 mm (4 mil) “natural” (semi-transparent) polyethylene film);
3. Fine mesh sieve; we prefer a brine shrimp net;
4. Binder clips/clothes pins (at least 10);
5. Soap (a few drops will go a long way to add to the water to break the water surface tension);
6. Water (4-6 Liters to fill the pans/catchments);
7. Water jugs/carriers able to hold 4-6 Liters;
8. Squirt bottles filled with 95% ethanol (for washing the sample out of the pan and off the sieve into the whirl packs or storage containers);
9. Ethanol (95% since some will be diluted through the process of washing and leaching);
10. Center weight (rebar or cut sapling for the midvein of the “V”);
11. Whirl packs or suitable storage containers;
12. Label paper and pigma pen to include a label in the sample.
Figure 2. XX
Additional materials for a single rigid trap:
1. A single 3 m (10 ft) long piece of 1.25 cm (0.5 inch) steel EMT conduit (electrical metallic tubing), and two 1.5 m long horizontal supports made from half of a length of the same conduit; the corners connected by EMT conduit elbows (Figure X);
2. Large rocks or sandbags (placed over each corner of the “U-shaped” end supports);
3. Four short rebar 0.25 m for stabilizing the center weight (2 on each side).
Additional materials for a single travel lightweight trap:
1. Rope [at least 9 m (30 ft)].
Figure 3. XX
Fig. 4 XX
Figure 4. XX
Things we have learned when deploying any Flight Intercept Trap:
1. We found it important to be near a body of water since the pans require lots of water and water is heavy;
2. A flat surface is essential;
3. Rigid pans are a must to avoid deformation when lifting them off the ground while servicing, A weak pan will bend under the weight of the water, and you’ll lose the sample. We have found orange paint trays (Figure X) to be strong enough and cost effective (<$6 each);
4. A large thin-mesh sieve will ensure you don’t miss any insects;
5. In high wind areas, the rebar that stabilizes the ‘v’ may need bracing; we found stacked rocks, or a cross of shorter rebar, works great;
6. If in a high evaporation area, adding salt to the pan solution will slow down evaporation, or use propylene glycol;
7. If animals are a problem with regards to drinking the catch fluid, or eating the catch, a fine chicken wire mesh may be needed; but don’t use something too large as to affect the insect catching efficiency;
8. Getting the lines extremely taught is essential. Any sag results in an uneven V and a reduced catch, as some part of the trap will be too high off the pans;
9. In rainy areas, the trough of the ‘v’ needs to drain, on both ends. Ensure water can pour from these ends without filling the collection pans, or undermining the support for the pans.
10. If during the course of the day you experience high winds or a storm do check the trap to ensure its integrity;
11. and finally – patience and perseverance.
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