Proper handling of specimens - pinning, labeling, shipping

Ideally, blow flies should be killed with fumes or with insecticides, not in liquids like alcohol or formaldehyde. The preferred fumigant is potassium cyanide, unfortunately this product has gotten hard to obtain and must be handled very carefully. Ethyl acetate is an alternative, but when you use this product in kill jars you must recharge them frequently and killed specimens can be brittle. Lightly spraying a low toxicity insecticide (like permethrin) in a jar is a way to rig a simple kill jar. This product lasts several months and is inexpensive, it is often sold to spray clothing to deter ticks. The disadvantage of this technique is flies don’t die as quickly, if you are netting a variety of specimens. BioQuip sells handy kill jars that are easy to use; I prefer the plastic ones that won’t break if dropped. Blow flies killed or stored in liquids become discolored and warped making positive morphological identification more difficult. If pinned specimens are in poor condition, I soak them briefly in ethyl acetate and dry with a hot lamp to “spruce them up” which can make characters easier to see. For some DNA work, specimens should be killed and stored in 95% ethyl alcohol. Formaldehyde and some other liquids destroy DNA and so avoid these products if specimens are collected for DNA research.

Pinned insects become dry and brittle within a few days after they are killed. Ideally, they should be pinned promptly while they are still soft and flexible. If you cannot pin specimens before they dry out, you should soften them for pinning and handling. For specimen softening, I use a Tupperware tub (or similar brand) about 7 x 7 inches, 2.5 inches deep. I put about an inch of sand in the bottom and flood it with water to wet it thoroughly, you don't want standing water. I put specimens on a foam pinning bottom set on the wet sand. You can also use wet paper towels rather than sand. I seal the lid for 12-48 hours to soften the specimen. Small, fragile specimens take less time, larger ones take longer. If you are just pinning specimens you can use a shorter period, if you are extracting genitalia it can take longer, 24 hours or more to get them soft enough. If you forget to check the specimens, they can be severely damaged if left too long because of over softening or mold. I always leave the lid off so the sand dries out when I'm not using it. If you use it too often, mold can become a problem and you may need to clean and sterilize everything.

For most blow flies, #2 pins are the ideal size except for very large blow flies where you may want to use #3 pins. I also use stainless pins which resist corrosion better than regular steel, but they are more expensive. When pinning, try to place pins where important characters won't be damaged. Unfortunately, you don't always know what’s important until you've pinned and begun keying specimens. The Lucilia group is one where important setae are obliterated if they are pinned in the middle of the thorax. It’s usually best to pin in thorax to the right of center so setae are preserved on one side of the specimen.

Once specimens are pinned, they should be properly labeled with information you think is important. Labels should be as small as possible, large labels can make specimens difficult to handle and store in boxes. Unlabeled specimens are virtually useless to a taxonomist, labeling is essential to make collected specimens useful when studying species. Provide enough information that 100 years from now someone looking at your specimen knows where and when it was collected and by whom. Giving location coordinates can eliminate confusion, especially for remote areas.

To get assistance with specimen identification, it is often necessary to ship specimens to specialists. Proper packaging of specimens is critical to ensure specimens are not destroyed in transit. Pinned specimens should be placed in a box with a pinning bottom (usually dense foam) that will hold the pins firmly and a piece of cardboard pressing down on the tops of pins to prevent them from getting loose in the box. If gentalia vials are attached on the pin below the specimen, you need to place pins along the sides so the specimen cannot spin. Once a specimen on a pin with a vial on it gets loose in your box, it can destroy many specimens in transit. When your box is prepared, it then needs to be packed in a larger box with “peanuts” or other packing materials to cushion blows in transit. It is prudent to put a “fragile-dead insects” label on the box; it may get handled more carefully. I have shipped many specimens all over the world using the US postal service and various other shippers with virtually no damage in transit. However, if you are shipping outside the US, check with people you are sending the package to for the best way to ship. Mailing or shipping services can be unreliable in some areas, it may be better to have someone hand carry specimens to those locations. Many taxonomists pay for special handling when shipping valuable specimens (like types). Most taxonomists will not place large numbers of valuable specimens in a single shipping box because there is always a chance of a catastrophic loss. For much more detail on a variety of entomological subjects including “how to pack specimens” see the following site: http://www.nps.gov/museum/publications/conserveogram/11-08.pdf

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Terry Whitworth, Ph.D.
Entomologist
3707 96th ST E
Tacoma, WA98446
Phone 253-531-7925
email: twhitworth@blowflies.net