So what do you need to join?

•  A Townes-style Malaise trap.  see below for more info about each requirement.

•  A grassy open spot to put the Malaise trap 

• Ethanol to collect insects in the Malaise trap

• Time to sample during 3 periods in May - June [typically] (each period is 3 days long [72 hrs])

• Time to sort the 3 samples to Order and weigh them

 Authorship on Publications and Use of Data 

 All collaborators who contribute data will have the opportunity to be authors on all papers, assuming that they agree in writing (via email) to 1) publish their data in open access databases and 2) review and approve of the publication.   

This is the format we used in our previous paper in Ecology (Dunn et al.  2023).   The data in that paper (2019-2021) are freely available at https://doi.org/10.6084/m9.figshare.20415819.v1 under the CC BY 4.0 license (see creativecommons.org/licenses/by/4.0/).

The CC BY 4.0 license allows others to use the data as long as they give appropriate credit to the persons that created the content.  In addition, we request that others respect the rights of collaborators by asking first to use the data, if it is a substantial part of their publication or product.  This helps to ensure that the data are used properly, which has been an issue in some previous cases where others have used data incorrectly because they did not contact the people who originally collected it.

 Protocol

This protocol is based on the recent paper in Ecology by Dunn et al. (2023. Extensive regional variation in the phenology of insects and their response to temperature across North America. Ecology, e4036.). 

We have added a few modifications to the protocol to simplify things.  Note that collaborators can send their samples to Peter Dunn (UW-Milwaukee; pdunn@uwm.edu  -contact me first !!) for processing if they do not have an analytical balance (accurate to the nearest milligram) or time to sort. 

Equipment

Malaise Trap.  We are using the standard BugDorm malaise trap.  It is very important that you use the same trap, because not all Malaise traps are the same. 

The trap we use is a Townes style trap, Model I or II (BT 1011), and it is available at shop.bugdorm.com. Note that other malaise traps may be slightly different in size (eg, the EZ model is similar but 20 cm shorter), so please check with me if you have questions.

In 2024 we are ordering these traps from Forestry Suppliers in MS.  They are handling the orders for Bugdorm (the manufacturer in Taiwan) and we are still getting a discount.

The cost of each trap is $203 + $23.45 shipping.  $226.45 total

Note that you will need to also get two poles (I just use some cheap wooden poles) and some ropes and stakes to erect the trap.

Below is a close-up picture from Mark Stanback of his set-up in NC using a model I trap.

Please remove the moth excluder on the newer traps (Model II; see picture).  We want to sample in the same manner as the previous study which did not have these excluders.

Ethanol for collection bottle

You will need about 3 liters (total) of 70-75 % ethanol for putting into the collection bottle.  See picture above.  This will preserve the insects you collect over the 3 day sampling period, and it also acts as a killing agent. Please make sure you are using ethanol (denatured is fine), not rubbing (isopropyl) alcohol.  If you need to dilute your ETOH, say from 95%, then you can use this formula:  amount of ETOH to use = (total volume desired * % desired (eg, 75%)) / % that you have (eg, 95%).  So if you want 2 liters of 75% ETOH and you have 95% ETOH, you would take 1579 ml of your 95% ETOH and add ~ 421 ml of water to bring it up to 2 Liters.

Put your trap in an open grassy area

For consistency with our previous study, we should all try to put the trap in or near a field or other open grassy area.  Preferably > 20 m from trees.

Agricultural areas or golf courses etc are fine, but it should be away from trees.

For example, below are pictures of various sites in the current network.

For this stage of the project, it would also be very useful to have traps near farms or other human-manipulated areas, as long as they are open grassy fields.    

If possible also please orient your trap North -South so it will intercept prevailing winds in most areas.

Latitude, Longitude and elevation of trap

Please send me (pdunn@uwm.edu) the latitude and longitude of your trap down to three decimal places and elevation to nearest meter. You can get this from the daftlogic.com site where you can enter your town and then zoom in to click on a point where your trap is located.  It will then give you the decimal latitude, longitude and elevation in a box below.  

Also please send two pictures of your trap similar to the ones above.  One picture from the side and one from head on.  Stand at least 10-20 m from the trap so the habitat is visible.  Also please do not include any people in the picture in case we use it for a publication.

Running the trap and estimating biomass

When to Sample:

At a minimum, we need 3 samples.  Each sample is from a 3 day (72 hr) sampling period.  These periods are spaced out in May and June (typically) at times that correspond to various stages of bird (tree swallow) breeding phenology. These are the “standard” periods described below.  The rationale for this is that with a limited number of samples per location (ie, 3) we need to make sure that we are sampling at relatively similar times of the year at each location.  The swallow times are admittedly arbitrary, but I study swallows and I want to study how insect abundance affects their reproduction, so that was a handy yardstick.  Of course you are welcome to add additional samples, if you want. For example, in the past I have sampled continuously (one sample every 3 days) from late-April to mid-July.

The standard sampling periods. --

First sample (“laying date”). -- The first sample is based on the average laying date for swallows in your area. This is 18 May in southern Wisconsin. We can calculate when the start date for your area is using the following formula that includes your latitude, longitude and elevation.

Your start date for the first sampling period is:  laying date [1=1May] = -23.024 + 1.1118*decimal_latitude + 0.0912*decimal_longitude + 0.0111*elevation[m].

Again, you can get your Lat, Long and elevation from the daftlogic.com site.

Second sample (“hatching date”). The second sample corresponds to the average hatch date for swallows in your area. To get this starting date, simply add 19 days to the start of the first sample above.  This is based on an average of 5 eggs in a tree swallow clutch (1 egg laid per day) and 14 days until hatching is complete.

Third sample (“nestling day 12”). This sample period starts at the time nestlings reach 12 days of age, so just add 12 to the start of your second sample above and this will be the start of your last sampling period.  This is 18 June in southern Wisconsin.

If you want to do more sampling, then I would recommend adding one more sampling period immediately after the ones above (so you would have 6 total). This will standardize “extra” samples a bit.  If you are a superstar of sampling, then you could also sample continuously, but to provide the most consistent samples across a large area, we need at least the three samples noted above.

Ethanol in the bottle.--

Use 70% ethanol in the bait jar (higher % alcohol will evaporate too quickly and lower % alcohol will allow the bugs to decompose too much).  Add about 400 ml of ethanol to the bottle; ie, 80% full.

Each sample period is 72 hours (3 days).

After collection, transfer ethanol + bugs to a new jar and re-fill the collection jar.

To compare with the results in Germany (Hallman et al.) we will first do a quick measurement of the total biomass after drip-drying (if you have a balance).  To do this, briefly strain the insects in a kitchen strainer like the one (6”) below over a jar.  In the Hallman et al. study they weighed the insects after the number of drips reached 10 seconds between drops. However, in my experience, this appears to be almost immediately after you put the insects in the strainer.

Place them in a petri dish or piece of wax paper and weigh to the nearest milligram (ie, 0.001 g).  I will provide a data sheet (in Excel) to collaborators.

Then proceed to sort to order and weigh again after air drying at room temperature for 1 hr. (see below)

Use a fine steel mesh strainer with about 1 mm mesh, like this.  Here is one on Amazon that is 6” wide.  

Sorting and identification.-- If you are sorting and weighing the insects yourself, then after getting the total biomass (above), please sort to Order (Flies, beetles, moths etc).  For this project we will only sort out Diptera (and the suborder Nematocera), Lepidoptera, Hymenoptera, Coleoptera and Hemiptera, because those were the most abundant orders in our previous study (>5% of total biomass) and, thus, the only ones with enough data to analyze statistically.  You do not have to sort out other taxa unless you want to.

We have been sorting out Nematocera (gnats, midges and mosquitoes), a suborder of Diptera, because many of them contain high levels of long-chain omega-3 polyunsaturated fatty acids, which are important to the breeding success of tree swallows and other aerial insectivores (see Twining, C.W., Shipley, J.R. and Winkler, D.W. 2018. Aquatic insects rich in omega-3 fatty acids drive breeding success in a widespread bird. Ecology Letters, doi:10.1111/ele.13156).

If you need help with sorting Nematocera, or prefer not to, then please contact me.  You are welcome to do finer taxonomic sorting, but please keep the sorting time to 1 hr (see below).

You can sort any way you want, in a petri dish with ETOH to facilitate moving the insects around, or on a piece of wax paper etc.  Whatever works best for you.  Just air dry for 1 hour. 

Weigh insects after 1 hour at room temperature.  -- To ensure consistent drying times (at room temperature), we allow 1 hour to sort your samples to order before weighing.  If you need more time, place the insects back in alcohol and sort again later. Or if it is obvious that you have a lot to process, just do them in a few 1 hour sessions. 

After sorting, put the insects in a petri dish, aluminum weighing boat or piece of wax paper for weighing. Weigh to the nearest milligram (0.001) on an electronic balance.  

Depending on the mass of insects in your sample, you may or may not need a highly accurate balance (ie, down to 0.001).  If you need access to an accurate balance, then please contact me.

Re-suspend the insects in 95% ethanol in case we want to do further identification or analyses (eg, count individuals or their sizes), or if you do not separate them out to Order after the initial weighing for total biomass.

For longer-term storage, I found that Amazon has some inexpensive options for 20 ml glass bottles.  Eg, this pack of 20 is $15 (currently).  For long term storage it is a good idea to put them a cool dark place that is an approved flammable storage container. Alternatively, you could drip-dry them, put them in plastic bags (or the bottles) and put them in a freezer.  This may affect biomass estimates, but the samples could be used for other purposes (counting numbers or DNA-barcoding). 

Thanks, and feel free to contact me with questions!

Peter Dunn (pdunn@uwm.edu)