Typically, historical documents undergo fumigation before being taken in for cataloging in order to kill insects and sterilize the materials. Sometimes, however, we encounter live insects during document repair operations or other types of processing. This column is a diary of my observations of a varied carpet beetle I encountered while organizing historical documents, chronicling its development into an adult.

December 21, 2015 — Bringing the Larva Home
A varied carpet beetle larva emerged while photographing historical documents from a prominent family’s collection at the Division of Historical Materials Conservation, International Research Institute of Disaster Science, Tohoku University. This pest infests parchment, fur, woolen fabrics, tatami mats, dried plants, and silk. As it is rare to encounter a live specimen, I placed it in a small plastic bag, took it home, and set up an observation room (Fig. 1). For food, at first I fed it bonito flakes.

February 16, 2016 — How many times will it molt!?
February 16th marked the first time the larva molted since the start of observation. On April 9, it molted for the third time. With spring in the air, I thought the larva might become an adult at any moment, but it easily made it through the summer without any major signs of change. In the end, the larva molted nine times before becoming an adult (Fig. 2).

September 24–25, 2016 — It is not moving…It is a pupa!
When I returned from a business trip, something seemed off. It was not moving. I thought that it might have finally died, but I left it alone for a few days. On September 29, just as I was about to throw the larva out, I looked in the observation room and discovered it in the middle of its eighth molt. However, its shape was different from before. I checked using museum past cards along with other sources (Fig. 3), and determined that it had become a pupa. Wondering what those five slit-like marks were on the pupa (Fig. 4), I touched them with a toothpick. The pupa then clamped down on the toothpick!

October 12, 2016 — It became an adult! However, then it vanished!
Today, the pupa of the varied carpet beetle finished molting and became an adult (Fig. 5). I was surprised at how rapidly it emerged from the pupa. I had intended to release it outside since it had become an adult without issue, but then two months later I found a new larva and made them live together. The following day, the adult suddenly vanished. Only its hard outer wings were left behind… I am sorry, adult bug, for making you end up as food for the larva!

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◎Related Column

The Little Ones Who Live in Ancient Documents
https://uehiro-tohoku.net/works/2020/2046.html