QUESTION:

Please explain the obvious differences between mouse scat and water bug droppings. What should we look for other then hair? Fibers can easily be mistaken for hair. Can you suggest an observation that can be determined while servicing, without any magnification?

ANSWER:

I guess I would start with the suggestion that magnification would be something you should always have available as you do inspections. This can be as simple and convenient as a hand lens magnifier that you can carry in your pocket, and these can be purchased for just a few dollars online, from some Univar offices, and from scientific suppliers like BioQuip (a link to them is on PestWeb). The best one I have seen in awhile I recently acquired, and it is 30X power with a built in LED light that makes it ideal for use in darkened settings, such as you might encounter in a warehouse. These are not just for looking at animal droppings, but necessary anytime you find some small insect, such as food or fabric pests, or need to examine a glue trap to see what those little spots really are. Are they bugs or dirt? Are they mites or beetles or springtails or psocids? Being able to properly identify what you encounter is critical to going about control procedures in the proper manner, and if you can do this in the field it saves time and effort.

Just for your info, and I don't mean to advertise someone else's product, but this hand lens is called Illuminate Loupe (Ledlight) 30X-25mm, and I found it online under that description for very low cost. With this, then, you can break apart something like a fecal pellet and examine its makeup, and this is the best way to determine the likely previous owner of that pellet. There are other hints with regard to the appearance, such as a "shiny" pellet that crumbles easily in the fingers is probably a bat dropping, and if you can identify the presence of insect body parts in that pellet (legs, body plates, wing covers) then you know it is a carnivore, perhaps the bat or maybe a lizard or frog. For those doing structural pest control you may be able to verify or dismiss whether the pellets are drywood termites, powderpost beetles, or carpenter ant frass.

Water bugs are, of course, cockroaches, and the larger species such as American and Oriental do produce fecal droppings that may be about the same size and shape as a dropping from the house mouse. The best difference is going to be the presence of hair in the mouse dropping, due to its habit of frequently grooming itself and swallowing hair. It may also be more common to find larger pieces of undigested grain or plant materials in the mouse dropping, whereas the cockroach dropping would be more likely to have a fairly consistent makeup due to its food being ground to a much finer paste during its passage through the throat and internal organs. But, you do need the magnification to see this, and without the close up look you could make a pretty good guess based on external appearance, but if that guess turns out to be wrong then your control program could be for the wrong pest.

Along with the recognition that it is one or the other - mouse or roach - you can place glue traps where the pathway of the pest appears to be, and verify the ID by catching something. If you find droppings and suspect mice you could verify this with a UV flashlight that should illuminate urine spots along the same area. Mice tend to urinate so darned often. You might also find other evidence if it is a rodent - smudge marks, gnawing, etc. Distinguishing between mouse and large roach droppings, as well as cricket droppings, probably is the most confusing distinction in scatology, so it would be advisable to use more than just a naked-eye examination to be sure. In general, the mouse dropping is going to be pointed at one (or both) end, but not always, so examine several droppings to be sure. In general insect droppings usually have more blunted ends, but again not always. Insect droppings also tend to be more rectangular or cylindrical in shape than the irregular shape of rodent droppings. You might even see lengthwise depressions in the roach droppings (but only with magnification) created by the anal muscles pressing down on the pellet prior to its exit from the roach's body.

And you folks thought Scatology was boring. This kind of stuff is good opening material in a social setting.