Hello Taylor;

I've made several sizes of funnel traps that seem to work well with active flyers. I've tried them on several species of dung beetles. I dug a hole in the soil, placed a peanut butter jar (or other appropriately sized container) at ground level and set a kitchen funnel over the jar's opening. The diameter of the funnel needed to be trimmed to approximate the diameter of the jar as well as trimming it at the bottom so that you are confident that the target species will fall through the bottom of the funnel.

Various ways of baiting the jar would keep the specimens from falling directly into the bait. A pill jar with a bunch of holes drilled into it may be a good bait cup inside the trap.

Validating the trap method as a statistically robust sampling method is another issue. I was only trying to collect the insects and didn't need to defend the method's statistical validity. I'm not competent to discuss the statistical problem.

Good luck with the hunt! Jim des Lauriers

Dear Taylor,

I assume you are strictly talking about Silphidae and not carrion associated beetles in general. I primarily use non-lethal traps when placing traps for Silphidae. The choice between lethal and non-lethal traps, as you call them, is off course strongly dependable on what you want to study. If you need to be able to compare the actual numbers and want to do some statistical analyses most researchers would prefer the lethal kind because of the certainty that no specimens could have escaped and you can be sure about the numbers you use in the analyses. Furthermore the lethal kind would be the one with some conservation liquids which means you can leave these traps for a certain amount of time before checking/emptying them. A third pro to the lethal traps would be that the beetles will not prey upon each other and the risk of predation by other animals are low. To my knowledge there have been, however, many surveys that have used non-lethal or "dry" traps and had good results. I used baited, non-lethal traps many times and with good results. The only thing you have to think about is how to keep the caught specimens inside the trap until you empty them. There are several different types of traps designed for this and it's your choice which one you want to choose. I really like to keep it straight forward and I use quite deep traps with eater a funnel or a metal mesh (mesh size about 1,5cm). The deep trap makes sure it is almost impossible to crawl out and the funnel or mesh prevents the beetles to be able to fly out (they are reasonably good fliers, but they will not succeed in flying straight trough a 1,5cm mesh, Silphidae are big, and even Thanatophilus is quite wide when in flight). In theory the funnel is much more reliable than the mesh, but I never noticed big differences. Make sure there is enough material (bait or some extra soil) so they can crawl away, this way they do not make escaping by flight there main activity. Last but not least: if you use non-lethal traps, make sure you empty them daily. This way the success rate between lethal and non-lethal traps would be about the same and you don't have a few hundred dead Nicrophorus vespilloides in every trap!

I hope this answer is somewhat helpful.

All the best with the survey!

Cheers,

Kevin

Thank you, Kevin. Many of your suggestions I've already included in the proposal on which I'm currently working, so it's good to know I'm on the right track. It was helpful to see the various factors laid out in full. I'm not sure if this against RG rules, but may I switch topic slightly? I was trying to decide what sampling strategy/method to use and it came down to two main options: transect line for gradient effects from rural toward urban sites or pitfall grids (stratified random) in various patch sizes of woodland. I've chosen the latter as there are several papers which discuss the effect of woodland size. Does this sound workable? I was going to go for transect originally, but it would essentially show the same thing but in a more complicated fashion. I'm also less familiar with transects for this type of survey.

Dear Taylor,

This all depends on the scale of the survey. I think that working on the effect of woodland size is easier to do if you are restricted in time. There are indeed more than several papers on the topic (with various groups like dung beetles, ground beetles, butterflies, etc.) so it's easy to have some other papers to compare your results with and get a bigger picture (in this way, even if the traps don't produce as good as you hoped you can still write a good paper on the bigger picture, so you'll have some more backup). An important thing to remember is that only several species of Silphidae are confined to forest habitats, and even more important is that some species have (as far as I know) a restricted distribution in Britain. I do not know where you're planning to do the survey, but the more species occur in that area, the better the results will be. More or less restricted to woodland habitats are Nicrophorus humator, N. vespilloides, Silpha carinata (only in the south of Britain?), Oiceoptoma thoracicum. You also have to remember that you have to make sure that the sites you compare are, despite the different size off course, very similar in type of woodland (dry pine forest on sandy soil is off course something different than a moist woodland with alder). So make sure you have both big and small woodland patches of the same woodland type, or restrict your survey on one or two woodland types only.

Probably I'm telling nothing that you don't know yet. If you have other questions on this maybe it would be better to send me a direct message through researchgate because we are indeed a bit off topic of the original question. I'm very interested in your survey since I'm also doing a project on Silphidae in Belgium.

Cheers,

Kevin

I agree with colleagues.

Sergey