Collecting & Mounting Specimens

[2022-02-17] Note: BioQuip announced they are going out of business on March 11, 2022. Most of the links on this page are to BioQuip supplies. I am working on a separate page listing alternative sources and will eventually update this page as well.

Have you ever wondered how all those butterflies in the museum were preserved? Or have you found an insect that you wished to humanely kill and place into your own collection? Here I will describe the basic techniques for capturing and preserving insect specimens.
First, the Lepidopterists' Society has compiled a statement on collecting, which is a very good guideline to follow. In general, a person should only collect for purposes of education and scientific study, and should show consideration in sensitive habitats and areas with small insect populations, so that an area does not become over-collected. Please review this statement if you are considering doing some collecting of your own.

Capturing insects
Most insects (including butterflies and moths) can be captured using a butterfly net.
Other methods of capturing insects include pitfall traps (ground-dwelling insects), light traps (night-flying insects), and sticky traps (scent-attracted insects such as flies).

Dispatching insects for specimens
The original method of killing (dispatching) insects is to use a "killing jar", a glass jar with an airtight lid, and a layer of plaster in the bottom soaked with a chemical such as ethyl acetate. However, these need to be regularly "recharged" with the chemical, which is also harmful to people, and butterflies often damage their wings from flying in the jar before they succumb to the chemical. I prefer to place butterflies in glassine envelopes, which keeps their wings folded and unable to move, and allows me to easily transport them. I then place them (still in the envelopes) into a freezer for several minutes, or longer if I do not plan to mount them for my collection right away. While in the field, I keep the envelopes with butterflies in a cooler.

Mounting insects for a collection
To preserve most insects for a collection, they must be dried. This involves inserting a pin through the thorax (middle segment of the body), and adjusting the wings and legs as desired. There are several methods of mounting butterflies and moths; some use wood spreading boards while others use foam, some hold the wings in place by pinning through the wing, while others use paper strips to hold down the wings during drying, and the process of placing the wings can vary greatly.  The following instructions are how I spread and preserve Lepidoptera.  I recommend trying different methods to find the one that suits you best, and also experiment with different ways of moving the wings into place; if you are left-handed, you might simply use a mirror-image of these photos and instructions, or you might wish to develop slightly different methods of placing the wings.
I apologize for the quality of these photos, I had to take them with my iPod one-handed, maybe next year I'll get a new and better set if I can get someone to take the photos for me while I'm spreading butterflies.

Before you get started, make sure you have all the supplies you need, and lay them out on a table or other work surface where you can easily reach everything.  You don't want to find yourself in a situation where you are holding a wing in just the right position and then can't find any pins or paper to hold it in place!
The supplies I use are all from BioQuip, a company in California that offers just about everything you need for insect and plant collecting, from cages, collecting equipment, cabinets, drawers, vials and other storage systems, plant presses, numerous books, and insect-related clothing and gifts.  Glassine envelopes and spade-tip forceps are also sold by stamp collecting stores.
I talk about collecting guidelines and supplies on the Collecting Lepidoptera page, but here is a recap of materials I use that are specific to preserving Lepidoptera:
Great Spangled Fritillary with its envelope.
Glassine envelopes - I always carry these when I am collecting, and almost always have some spares tucked away in my car and purse for those occasions when I come across something new in a place I didn't plan on collecting in.  Lepidoptera can be stored in these envelopes for years.  They can be kept in air-tight plastic containers until you are ready to spread the specimen (an air-tight container is essential for keeping other bugs such as dermestid beetles from destroying the specimens).  Whenever I collect specimens, I keep all the envelopes from one trip together in a container with a scrap of paper that has general information about the location, while each envelope has more specific information, such as GPS coordinates and whether or not I photographed the butterfly before collecting it (see photo).  The smallest envelope size (also in this photo) fits most butterfly species found in the Pacific Northwest. Next size fits some larger species and smaller swallowtails, square size fits largest butterflies. Largest size is useful for large tropical species.
Labeling pens - fine-point pens for writing specimen labels, and are almost the only thing that will reliably write on glassine paper.  Always carry at least one with the envelopes so you can record the location and any other information onto the envelope, so the information doesn't get lost or forgotten.
Spade-tip forceps - an absolute must for handling butterflies and moths, either dead or alive. I keep at least three on hand.  Any forceps you use must be completely smooth to reduce loss of scales, and a rounded or spade tip, rather than a sharper tip, reduces the chance of damaging wings and other body parts.
Insect pins - size 000 to 00 for smallest butterflies, size 0 to 1 for most butterflies, size 2 to 3 for large butterflies.  I usually use 00 for small Lycaenidae (blues/coppers/hairstreaks), 0 for larger Lycaenidae and small skippers, 1 for most other medium-sized butterflies, and size 2 for swallowtails and larger Nymphalidae (such as Mourning Cloaks and larger fritillaries).  I only use size 3 for large moths and beetles.
Glass-headed pins (also found at sewing shops) - use to hold paper strips in place on spreading board, and for adjusting and holding legs and antennae in place.  Insect pins can be used as well but are less secure; glass-headed pins are easier to grasp, and are shorter with a larger diameter than insect pins, making them more sturdy.
Pinning board - I use this new blue one, but there are other styles, depends on personal preference (previously used the Versaboard, see this blog post about these two boards).
Glassine paper strips for holding down wings.
Glassine pinning strips - I've found the smallest size is the most useful (see photo), although larger widths can be cut down to any size desired.
Curator's block - holds pins and forceps, or this one if you just want one for pins. I have one of each, and use them to keep my different pin sizes separated.
Repair adhesive - great to have on hand, clear nail polish works well too, but be warned: even the smallest drop will dissolve a hole in foam pinning boards!  I either have to be very careful not to drip any, or use a wooden board for wing repairs.

Beginning the spreading process
Once your supplies are laid out, remove the butterfly (or moth) from the envelope.  If it has dried to the point where you cannot open the wings easily, you will need to rehydrate it by placing it in an air-tight container with moist paper towels or a washcloth.  I've tried several methods of rehydration and have had mixed success, so rather than try to explain how to do it here, I recommend you find instructions elsewhere on the web or refer to this book: Basic Techniques for Observing and Studying Moths & Butterflies, by William D. Winter Jr.

Inserting the insect pin
Grasp the thorax with forceps or your thumb and forefinger
Grasp the butterfly by its thorax (middle of the body) with forceps, keeping the edge of the forceps just below the wing joint.  Squeeze gently to open the wings; if the wings do not open, position the forceps slightly lower and try again.  You can do this by hand also, using the forceps with your other hand to gently bend the wings open even further.  
Insert the insect pin into the center of the thorax (rounded area between the wing joints), and push down until about 1/4 to 1/2 inch remains above the butterfly.  Usually I grasp the butterfly with forceps in my right hand, squeezing until the wings are open enough to see the top of the thorax, then inserting the pin with my left hand.  I turn the butterfly at different angles to ensure the pin is going in straight.

If holding the butterfly by hand, you can use forceps to open the wings

Positioning the butterfly on the spreading board
Choose a groove size that comfortably fits the width of the butterfly.  If the groove is too big, the butterfly will swivel around too much when you try to position the wings.  If this is the case and you don't have any other groove size choices, then place the butterfly to one side of the groove, and position a pin next to the body to keep it in place.  Because I always position the wings on the right side first, if I have problems with the groove size, I put the butterfly against the right side of the groove; this secures the butterfly when I pull to the right and pin down the wings on that side, and then the pinned wings (usually) keep the specimen in place when I pull to the other side to position the left-side wings.

Clockwise: center the butterfly in the groove, gently open the wings enough to allow room for your finger,
press down on the pin until the base of the wings is level with the top of the board.

Placing the Wings
I have found that the most comfortable method of positioning the wings is to have the board sideways, with the butterfly's head to the left, and to start with the right-side wings.  Some people prefer to use a small insect pin (such as size 00 or 000) to pierce the forewing and pull it forward, but no matter how small the pin is, it of course leaves a hole, and occasionally the pin slips and tears the wing.  Using forceps has drawbacks as well; some scales can be rubbed off, and especially in smaller butterflies, the wings can be torn by the action of pulling them forward with the forceps.  There are two methods with forceps that I use interchangeably:
1) holding the forceps with my left hand, I grasp the leading edge of the right forewing and slowly pull it forward (to the left).  This method seems to be a little more successful in placing the wing without damaging it (pulling rather than pushing), but is a little more awkward when trying to pin the paper over the wing to secure it in place, because I have to cross over the butterfly with my right hand.
2) holding the forceps with my right hand, I grasp the wing so that the tip of the forceps is just behind the leading edge of the forewing (shown in photos below).  I then use my left hand to grab a strip of paper with a glass-headed pin and secure the wing in place.
In both cases, the lower edge of the forewing should be perpendicular with the body, forming a right-angle.  For the rest of the instructions, see the photos below.

Showing method #2: with paper strip ready to use (upper left), hold forceps with right hand and carefully move forewing
forward until the lower edge of the wing is perpendicular with the body.
Once the forewing is in the correct position, use your left hand to pin a paper strip over the forewing (left).  Move your left forefinger onto the paper strip and over the forceps to secure the wing, then gently slide the forceps away (right).
Slide your finger down the paper strip to the lower edge of the forewing to hold it in place, then use the forceps to pull the hindwing up until there is a small gap between the forewing and the outer edge of the hindwing (left).
Then slide your finger down the paper strip to the hindwing and pin down the end (right).
For larger butterflies such as this, when the paper strip does not overlap the small space between the two wings (providing an area to place another pin, see anglewing photos below), you will need to place extra paper strips as shown to keep the wings from slipping out of place.
Once the right-side wings are secured, position the left-side wings in the same way.
Securing the left-side wings
Once the wings are in place, turn the board so the butterfly is facing away from you and make sure the wings are all lined up straight.  Now position the antennae; very carefully use a glass-headed pin to slide each antenna towards the forewing, and place the pin so that the antenna does not spring back.  Slide the antenna under the paper strips if possible, partly to hold it in place and partly because if the antenna is on top of the paper strip, it is easy to accidentally break it off when removing the paper strips after everything is dry.
Finally, use two pins to prop up the abdomen so that it is level with the top of the board and to keep it from drooping as it dries.  Occasionally the abdomen will bend upward as it dries (I usually see this with small blues), so I always place a third pin at an angle over the top of the abdomen to ensure it stays in place.
If a wing is not lined up correctly, or slips down after you have pinned the paper in place, grasp the upper edge of the wing with forceps and gently slide it back into place, and re-adjust the pins or add additional paper strips as needed.  Note in these two photos how the forewing has slipped down against the green center pin (left), so I moved the wing back, touching the top white pin (right).  I then moved the green pin closer to the bottom edge of the forewing and added another paper strip (see below).
Green Anglewing, spreading complete

Removing completed specimens from the board
Specimens will need anywhere from two days to two weeks to completely dry and harden, depending on the size of the butterfly or moth.  The way I test to see if a specimen is ready to be taken off the spreading board, is to remove the pins holding up the abdomen, and use the side of one of them to gently press against the side of the abdomen.  If the abdomen moves, it is not ready, but if it is hard you can remove all the paper strips and see if any of the wings start to slide out of place.  If everything is stiff and stays in place, you may remove the specimen from the board, slide a label onto the pin with the specimen, and place it in a display case or storage drawer.
If a specimen is left on a board longer than a week or two, it may become infested with dermestid beetles that will easily reduce an insect collection to dust.  To prevent this, keep a close eye on the specimens on the board, and if they must remain on the board for more than a week or two, once they are dry pin them into a container with a foam bottom and place them in a freezer overnight before adding them to your collection.

Dealing with broken wings
Everyone will encounter this problem, no matter how careful you are.  Either the wing will slip, often resulting in a chunk ripped off the edge where the forceps had a hold, or your hand will inadvertently jerk and rip an entire wing off, or a specimen may simply be too dry and fragile by the time you are ready to spread it, so that all the wings snap off when you attempt to open them.  I certainly have my share of "oh no!" moments, but have learned how to repair most accidents.  It is impossible to fix most tears around the edge of the wings, but some split wings are reparable, and if an entire wing is broken off, it is fairly easy to repair.
Left forewing broke off, and right hindwing split
If a wing breaks while you are spreading a butterfly, simply pin it next to the specimen and continue to position the other wings as you normally would.  Once the butterfly is dry, you can glue the wing back in place.  The photo at left is of a female Anna's Blue that I had trouble with recently.  It was in the freezer for too long and was more dried out than I thought (the other specimens were fine, but smaller butterflies dry out faster).  The wings opened enough that I thought it was fine, until the last few millimeters of moving the wings into place, when one of the forewings snapped off and the last bit of the right hindwing decided not to move with the rest of the wing, resulting in a split.
Repairing a butterfly is very delicate work, but really isn't terribly difficult if you have a steady hand.  I use the repair adhesive I listed above in the supplies section.  I dip the tip of a glass-headed pin into the glue until there is a tiny droplet on the pin, then then carefully dab it onto the part of the wing I am repairing.  I'll have to have someone photograph or record me doing that sometime so I can illustrate it here.


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  2. This is truly an excellent contribution to the literature on spreading, collecting, mounting, hydrating, and repairing Lepidoptera. I had really lost heart, completely discouraged after my attempts, but this complete posting on all of the problems I have run into with solutions and encouragement not to despair or give up has reanimated my commitment to serve my desire Ito illustrate butterflies and moths accurately. There are so many in depth useful tips beyond what I have seen before and the kindness to share mistakes and efforts to salvage mistakes, that make the true leader. Thank you, Caitlin LaBar, Northwestbutterflies Blogspot. I will let all of my Nature Journal students know about you.

  3. Thanks for this post. I've been trying to improve my lep collection and this has been a fantastic resource.