By Kevin Hong
What is insect pinning? Simply put, it is the pinning of caught insect specimens into a case so that the specimens can be studied and displayed. It’s a method for naturalists to survey insect populations within geographical regions, and to learn what lives where. Properly done, each pinned specimen should also have a label with information accurate as possible for the time and space within the insect was caught, such as date, time of day, and latitude / longitude. Besides the advantage of having this information neatly tacked to the specimen, pinning prevents the brittle insect bodies from breaking by freeing the specimen from surface contact or direct handling for further observation.
On August 9th, we met in front of the Joaquin Miller Ranger Station for our insect pinning event led by Eddie Dunbar from the Insect Sciences Museum of California (ISMC). To begin the afternoon, we forayed into the park to hunt for insects toting nets and small, cylindrical vials to hold specimens. Eddie advised us to look in bushes, under rocks and logs, on leaves, windowsills, and car bumpers to find insects. Among the critters we saw in the woods and blackberry bushes were bees, flies, false tarantulas, grass spiders, wood beetles, termites, a tropical centipede, and a Jerusalem cricket.
After bug hunting we regrouped at the picnic tables in front of the Joaquin Miller Ranger Station and put our insect specimens into kill jars – jars containing paper towels soaked in ethyl acetate (the active ingredient in nail polish remover) – that would slowly and relatively peacefully incapacitate and kill the insects in preparation for pinning. An alternative method of incapacitation, and probably the best one if you can do it, is to put the container with the bug inside a freezer for about twenty to thirty minutes. The balance of an insect’s being depends on its body temperature relative to its environment’s temperature, so any insect (or spider, or any other sort of arthropod) will slow down and eventually die peacefully after spending enough time in a freezer.
Since the focus of this event was to practice technique, the only insects we put in the kill jars were those that occur in great abundance and aren’t in any way threatened as a species.
After waiting about fifteen minutes, the insects were ready. Eddie gave us our own insect pinning kits, each containing two clear plastic boxes with Styrofoam floors on the inside for collecting insects, stainless pins, a wood block for making specimens and labels level, forceps, and a loupe. We pinned the insects level and into the Styrofoam bases of our boxes, along with a small strip of flea collar for deterring pests from getting to the specimens. “Dead insects are a surprisingly popular protein source for live ones,” Eddie told us. The flea collar – specifically ones that contain propoxur – prevents pests from getting into your collection. Eddie warned specifically against collars or mothballs with paradichlorobenzene, as they will produce vapors that will weaken the plastic of your collection box.
Insect collecting is a fantastic way to create a record of what lives in an area, but keep in mind that many open spaces, including all of the East Bay Regional Parks, require a collection permit (for this event we were able to collect under the permit held by the ISMC). If you want to record or identify an insect without collecting (i.e. killing) it, you can take a picture of it and post your photo to www.inaturalist.org.