Insect Pinning and Preservation

    About half my collection from Dr. Cooper's Insect Ecology Class, 2014

BEFORE YOU START:
       As a child I was much more concerned with a) catching insects and b) keeping them alive and dragging them through my poor mother's house than I ever was 'collecting' them in the weird-Victorian-hobby sense of the word. To some degree I'm still this way; back in 2010 I got my first good point-and-shoot digital camera and for the most part I still enjoy taking pictures of insects far more than I do...well...killing them. There's no nice way to put it; to make an omelet, you need to crack some eggs, and to make a complete insect collection you need kill some insects. Unless you are very dedicated to pinning only fresh, already-dead insects (see: vulture culture, the practice of preserving and crafting with the body parts animals that died of natural causes), you will have to kill the insects before you pin them.

     To accomplish this, you're going to need a killing jar. This is pretty much exactly what it sounds like: a jar that holds a killing agent and has an air-tight lid that allows the insect to suffocate on the killing agent's fumes. For adult collectors, glass works best because it stands up to most of the chemicals used to kill the insects; for children, the risk of dropping a glass jar pretty well outweighs whatever advantages of using glass, so plastic is more suitable in that case. Our class used jars ordered from an entomological company, but any jam jar or possibly even peanut butter jar will do. Once you've selected your jar, you're going to need some sort of absorbant material to collect and release the killing agent. Our class used quick setting plaster poured directly into the bottom of the jar (though be aware that this can backfire; several students have had their plasters detach from the bottom and flip over, crushing insects and making them difficult to get out of the jar) though any absorbent material, from paper towels to corrugated cardboard cut to fit the bottom of the jar  to cotton balls will do in a pinch. Just make sure the top layer of whatever you choose is mostly dry; hairy or scaly insects, such a butterflies, can damage themselves on damp surfaces.

     Next, you'll need to decide on a killing agent. Historically, a number of dangerous and ill-advised chemicals have been used such as ether, chloroform and potassium cyanide; a bit overkill, if you ask me. The best and safest bet for pinning insects is acetone-free nail polish remover, which contains ethyl acetate and kill insects within a few minutes. Similarly,you could purchase pure ethyl acetate which kills insects a little quicker; this can be expensive, however, depending upon who you're buying from. Be aware that ethyl acetate will damage plastic jars in the long-term, so it may be best to go with rubbing alcohol if you're using a plastic jar. Rubbing alcohol is also less dangerous to use with small children and has the advantage of being available almost world-wide, in case you're collecting in remote areas with nothing but a simple general store to get supplies from.
     Now we get to the actual pinning. Pin as soon as the insect is dead whenever possible (just make SURE it's dead; I've had a couple incidents with insects re-awakening on the pinning board, and it's a whole different kind of guilt trip). The insect will never be as flexible as it is when it's freshly killed. If you're starting with a 'dry' insect, one that has stiffened up and whose joints are no longer pose-able, you'll want to relax it for some time before trying to get it into the position to pin it. Relaxation can be accomplished by filling a small tupperware container with a wet sponge and several layers of paper towels. Placing the insect inside a plastic bottle cap or watchglass will allow the body to loosen up with the high humidity inside the container. A word of caution, however: these are also favorable conditions for mold growth. I once lost about a dozen bees, wasps and hornets to mold this way. Relax in small batches, no more than two or three at a time, and be especially wary of insects that you take from standing water (my wasps and bees were from a swimming pool filter, for example. Lesson learned.). Ethyl acetate in the relaxation chamber may help keep mold down and gets the insects nice and 'floppy'.


PINNING AND POSING:
     You can certainly buy display boxes from entomological companies and use that as your primary pinning surface, but to prepare the specimen for mounting it helps to have a thick (1 to 2 inches is ideal) piece of Styrofoam board so that you can push the pin far down into the Styrofoam and pin the insect high on the pin's length, near the head if at all possible, while the specimen's legs and ventral surface can still touch the Styrofoam board's surface. This makes for easier labeling and less damage when the time comes for transferring the specimen from one box to another.

Notice how dragonfly that was pinned close to the bottom of the box has all of its feet on the ground. This make posing easy, but also leaves it vulnerable to having its legs snap off. The other dragonfly was pinned with the reverse pinning method:

 I inserted the pin through the thorax and put the pinhead in the Styrofoam. I post the legs the way I wanted them using a bit of note card and then laid the wings out flat. I gave this one about three days to dry. 

Much prettier than that low-mount!

Tah-dah!

   Before you begin pinning, I find it helps to take the insect's appendages through their full range of motion. Figure out where the stiff points in each joint are and try to avoid pushing past them. Then, once you're confident with your specimen, you can put your first pin into the insect. Most institutions and private collectors still use the tried and true method of putting the single 'permanent' pin through thorax or high on the abdomen, allowing for a horizontal presentation of the specimen. When insects are being prepared for 3D imaging, Micro Ct reconstruction or 2D high-resolution photo stitching,  however, it makes way more sense to pin them through the rectal opening to display as much body surface to the camera as possible (if you have a moment, this article explains this in more detail and is definitely worth the read).  However, these systems aren't common yet in a lot of institutions, so we'll proceed with horizontal instructions. Once you've gotten your first pin though the thorax, you'll want to get the legs into position. Many institutions try to save space in large collections by folding the legs under the body, but I've always felt that this is aesthetically unattractive and does not allow people using the preserved specimen to see what the insect looked like when it was alive. My usual choice, especially for orders like Othopera and Coleoptera, is to pin the insect dorsal side up, adjust the legs, mouth parts and antennae into a natural pose, secure the pose with with as many pins as necessary (this can be mean dozens per insect, so have plenty on hand before you start) and then allow them to air dry and harden up for a few days. You'll know it's ready to have the extra supporting pins removed when you try to bend a leg and there is no give in the joints. Be aware that some insects take much longer to dry than others; something like a leafhopper can take less than 24 hours, but the one wheel bug I've tried to pin has been on the Styrofoam for nearly a week and it still hasn't hardened up enough to remove its support pins yet. Size has a great deal to do with this; large, hard-bodied insects seem to take a very long time to harden up, while smaller and softer-bodied insects will desiccate fairly quickly. Large insects that have a lot of soft tissue, such as praying mantids, grasshoppers and walking sticks, can be punctured a few times in discrete locations (between scutes of the exoskeleton or underneath the thorax where no one is likely to look)  with a pin to allow fluids to drain and to encourage drying instead of rotting.
     Pins are not the only way to give your insect the support it needs to maintain the pose you'd like as it dries. Mantids are very difficult to preserve in their 'praying' pose, but one trick is to cut a small piece of cardboard or note card paper to fit under the 'armpits', allowing the head and neck to be supported while the front appendages are pushed outwards. Don't be afraid to get creative.

I was having some trouble getting this mantis to keep 'praying', but a piece of note card did the trick. But what about his drooping abdomen?

There we go. Much better. 

BUTTERFLIES AND MOTHS:

The first insect I ever pinned was a large sphinx moth I found freshly dead in my garage. Pictures of the pinning process and the finished product are below:

When it comes to butterflies, bigger is usually easier to deal with. 

    Butterflies and moths are a little more difficult to pin, but are extremely rewarding when they come out well. My personal method differs from what most institutions teach, but it's easier for beginners to follow and gives good results. Before I touch the butterfly, I cover the styrofoam board with a sheet of plastic. Saran-Wrap or 1 gallon plastic bags cut open work fairly well, though I've heard of people getting good results with wax paper too.  I start opening the wings slightly with tweezers and inserting the first pin between the wings and through the thorax, usually so that the pin's point comes out between the first set of legs on the ventral surface. Once I get the thoracic pin correct, I push the body down the pin until the dorsal surface is almost flush with the pin head.Then, I open the wings back towards the ventral surface, flip the pin head-down and push the pinhead into the Styrofoam just enough to keep the pinhead fully inside the board. I position the wings on the board the way I want them and then secure them with either a strip of plastic pinned tight to the board or just directly with pins (this is dependent upon size and wing shape). For the legs, I try to put them into the position they'd likely occupy when the insect is flying (either flush against the body or with the feet slightly turned out and away). The legs can be kept in place with a piece of cardboard or plastic; usually, if you're doing a reverse-pinning like I did on the sphinx moth above, the weight of the plastic will keep the legs pressed into the right position as they dry.  Larger butterflies and moth are much easier to pin than smaller ones; some smaller moths, especially, have wings that tear like tissue paper when pinned. I've yet to find a way to get these specimens presentable enough to keep.

DISPLAY:
     Displaying the insects is a matter of purpose and personal taste; most institutions label their specimens with capture location, captor and year, and keep them in glass cases in climate-controlled containers with moth balls to avoid dermestid beetle damage. For my personal collection, I use baseball cases for large insects and soon I'll be looking to get a few shadow boxes to display specimens by order. Like any other work of art, try to keep them out of the sun to avoid loss of color.

So this is just about everything I know about insect preservation. Remember the basics and you'll have your collection growing soon.
     Happy Hunting,
       -Rebecca Dickey