[Nhcoll-l] Question about entomological collections

[Douglas Yanega]

On 3/3/21 6:53 AM, Aline Donini wrote:
>
> Hello,
> I’m working on the preservation of entomological collections in 
> France, and I want to deepen my practical knowledge.  I am looking for 
> someone with knowledge of chemical interactions between specimens and 
> fumigants.  I have observed some crystals on pinned insects. When I 
> touch the crystals with a brush, they break down into powder. In the 
> entomological storage box, there is, I think, some naphthalene. I am 
> supposing that the naphthalene is somehow recrystallising on the 
> insect bodies?
> I have seen a reference: Kelman, Lisa ( 
> https://www.bcin.ca/bcin/detail.app?id=182461 
> <https://www.bcin.ca/bcin/detail.app?id=182461>)), but cannot find the 
> article.
> The specimens date from the 1930’s. The naphthalene, I think has been 
> present for at least 30 years.
>
Hi, Aline. There is an organization specifically dedicated to 
entomological collections, the Entomological Collections Network. It is 
over 20 years old, international in scope, and with a few hundred member 
institutions. They have a mailing list much like nhcoll, at

ECN-L at LISTSERV.UNL.EDU

and they also have a FaceBook group, at

https://www.facebook.com/groups/entcollnet

Questions about curatorial practices and techniques are among the most 
common topics of discussion. I would encourage you to subscribe to one 
or both of the above resources.

As for your specific question, naphthalene does recrystallize from 
vapor, onto pins and even the specimens themselves. It is also not a 
very effective control agent for the most common museum pests (carpet 
beetles of the genus Anthrenus): in essence, it has little or no effect 
on the survival of carpet beetles or their larvae, though it does appear 
to reduce the odds of beetles entering the collection. That is, the 
beetles may not find their way into your collection as often as they 
would without the napthalene, but if a beetle finds its way inside, it 
can still do considerable damage because its larvae will generally 
survive and feed to maturity.

Policies and practices regarding fumigants vary considerably among 
institutions, but the bottom line is that there is nothing that is 
genuinely effective at killing dermestids that is also not a significant 
health risk to humans (the three most common fumigants - naphthalene, 
paradichlorobenzene, and dichlorvos - are all toxic, and only the latter 
is a genuinely effective killing agent). In places where regulations 
surrounding human health risks take priority, such as where I am in 
California, we are legally prohibited from using ANY fumigants at all, 
and can only control pests through a combination of finely-crafted 
cabinetry (to minimize beetle penetration) and freezing of specimen 
drawers. There had been naphthalene in our collection, but the last of 
it was disposed of over 20 years ago.

I hope this is helpful,

-- 
Doug Yanega      Dept. of Entomology       Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314     skype: dyanega
phone: (951) 827-4315 (disclaimer: opinions are mine, not UCR's)
              https://faculty.ucr.edu/~heraty/yanega.html
   "There are some enterprises in which a careful disorderliness
         is the true method" - Herman Melville, Moby Dick, Chap. 82