Fumigant Lifetime

[jhyatt]

I use dichlorvos strips ("No-pest strips") in my lep collection. I cut the large yellow slabs one can purchase into roughly 1/2" squares and pin one in each Cornell drawer. This seems to work well - I've had no infestations since I started using this material years and years ago.

But I wonder how one can tell when the fumigant is exhausted and should be replaced. I've been doing this when the originally deep yellow squares fade to a very pale yellow color. This takes about 3-4 years in a drawer of average tightness, in my experience.

Am I being risky and should be replacing them more often? Or am I leaving money on the table by replacing them too frequently? Does anyone have any actual data on the useful lifetime of dichlorvos strips?

Cheers,
jh

[Paul K]

In some of my drawers I haven’t change them since I started using these in 2015-16. They are pale yellow but so far no pests, I’m not sure if they still do work or I have no pest in my room.

[Jshuey]

I put little squares of dichlorvos in about three years ago. And I just saw a dermestid last month. So - about 2+ years? Or less - I assume that you get some time after the strips quit working - right? I use smaller squares than you do - more like 1/4th inch.

I'll be renewing it all over the long weekend this week.

John

[jhyatt]

In some of my drawers I haven’t change them since I started using these in 2015-16. They are pale yellow but so far no pests, I’m not sure if they still do work or I have no pest in my room.

Of course the usable lifetime may vary from drawer to drawer, depending on the rate of air exchange inside the particular drawer. I renewed all of mine about 1 year ago; I guess I'll let them go at least another year, or 2 or 3, unless I find an infestation... and I'll replace it in any drawers where I notice an unusually pale chunk of dichlorvos strip. I suspect there's no valid general answer to my original question.

jh

[Jshuey]

The other thing to ponder, this stuff is not good for you. It can cause neurological damage. My bug room is pretty small, so I use it as sparingly as possible.

John

[mothman55]

Agree with Jshuey, as I keep my roughly 80 drawers in my basement. I would be concerned that 80 chunks of no pest strip might be a health concern for family that spends lots of time in the basement, obviously not in the room with the bugs, but what's to keep it confined to that particular room. I used to use moth crystals, but my wife put a stop to that many years ago as any time she went near the "moth room" as we call it, she could smell it, and its not safe either. So now for the past few years I am using cedar oil, not in the drawers, but in cabinets and about the room. I soak cedar disks in cedar oil, and place them around the drawers in the room. The cedar smell is rather pleasant, and diminishes after a day or two after treatment. I repeat this about every 2 or 3 months. So far no pests, but I know cedar oil will not kill the pests, only deter them, so I check my most valuable specimens routinely, just a flashlight to look under the bodies for any dust.

[jhyatt]

The other thing to ponder, this stuff is not good for you. It can cause neurological damage. My bug room is pretty small, so I use it as sparingly as possible.

John

Yep, it's a cholinesterase inhibitor. My bug room is a roughly 60' X 40' open basement, fairly well ventilated, and I don't spend huge amounts of time there. Still, it's a concern. Paradichlorobenzene also can produce neurological effects. PDCB is more volatile than dichlorvos and needs replacement much more often, so I've switched to dichlorvos. But I think I will follow Shuey in using smaller pieces than I have been.

It's a dilemma; I can see why big museums have gone over to watching and freezing when infestations occur. But without a really big freezer, that's impractical at home.

jh

[Chris Grinter]

A chest freezer can fit drawers vertically, years ago I had one in a lab that could easily fit 6 at once. Pretty cheap to purchase and run.

[jhyatt]

A chest freezer can fit drawers vertically, years ago I had one in a lab that could easily fit 6 at once. Pretty cheap to purchase and run.

Got one, but it's too full of boxes of papered leps to hold any drawers!

jh

[Chris Grinter]

A chest freezer can fit drawers vertically, years ago I had one in a lab that could easily fit 6 at once. Pretty cheap to purchase and run.

Got one, but it's too full of boxes of papered leps to hold any drawers!

jh

Haha yes just need the discipline to use the freezer for nothing other than pest management.

[jhyatt]

A chest freezer can fit drawers vertically, years ago I had one in a lab that could easily fit 6 at once. Pretty cheap to purchase and run.

Got one, but it's too full of boxes of papered leps to hold any drawers!

jh

Haha yes just need the discipline to use the freezer for nothing other than pest management.

Let's see now: I take the boxes of papered stuff out of the freezer, take the fumigant out of drawers, put it into the boxes, put the boxes on a shelf, and put the drawers in the freezer, and I'm good to go!

[Chuck]

I've pretty much gotten away from fumigants. If I find any beetles during summer I toss a PDB in the drawer and that seems to take care of them.

I'm "fortunate" enough that during winter I can rotate most of the collection through the sub-freezing garage. Purportedly, the drawers have to go through two freezes to catch adults then eggs, but in my experience one rotation through a freeze does the job.

It's my suggestion to find a way to freeze drawers, always keep humidity under 50%, and avoid fumigants. This, of course, is not always possible, but for those who do have the space (yes, you do John) a freezer (or second freezer) is the way to go.

[jhyatt]

[quote=Chuck post_id=8523 time=1701093488 user_id=100

It's my suggestion to find a way to freeze drawers, always keep humidity under 50%, and avoid fumigants. This, of course, is not always possible, but for those who do have the space (yes, you do John) a freezer (or second freezer) is the way to go.
[/quote]

Summertime humidity is kept at around 30-35% with a dehumidifier and in winter the heating takes it even lower, so that's not a problem. But noticing which drawers need a freeze treatment is a bit of a problem -- With close to 600 drawers, I always have some I haven't opened or looked at in a year or three... Guess I could institute a 6-monthly program of looking at everything, though. A 2nd freezer might be a good idea, too. Mine is the smallest chest freezer I could buy, ca. 5 cu. ft.

Tks,
jh

[Chuck]

Up in the NE Great Lakes area, outdoor humidity is about 65% - 75% for six months, then 30% the other six months. Even with multiple dehumidifiers running sometimes in summer it's a struggle to keep the bug room under 50%. This is when the problems start.

One thing I've found is that once a drawer has an infestation, even minor, it's more inclined to in the future. And, if a drawer gets badly infested, it's more likely to get badly infested again. Maybe they find it easier to feed on already-damaged specimens. Point is, I know which drawers are likely to have a problem. I also flag them with those little stick-on arrows so I can find them easily for inspection.

Another observation- off topic somewhat- is drawers that get infested. When I took over maintenance of the Iveson collection (14,000 specimens, 150 drawers) there were substantial infestations in some drawers, while the drawers adjacent would be fine. Oddly, there seemed to be zero correlation with the seal on the drawer- some badly infested seemed to be extremely well made and well sealed, while some with never any infestation were loose fitted and badly constructed drawers. I never could figure it out.

Anyway, when the garage is sub-zero (25F or less) I rotate four drawers at a time through the garage for three days. Four because that's the number I can carry safely. Only last year did I run out of cold-enough days to do the entire collection. If we had room for a chest freezer I'd get one, but wife says I have too much stuff already, so no chest freezer. A Porsche is also out of the question.

[alandmor]

I just wanted to mention a possible alternative to the traditional No Pest Strips mentioned here. Hercon Vaportape II has the same active ingredient (Dichlorvos,10% vs. 18.6%) but in a more user-friendly, 1" x 4" thin strip and easier to cut. Vaportape II is intended to use as a fumigant in outdoor insect traps and is available from any place that sells insect pest management or insect monitoring supplies such as Great Lakes IPM, https://www.greatlakesipm.com/. The label says to replace after 12 weeks or when effectiveness diminishes. I'd imagine they'd last longer in an enclosed drawer. I have not used either product in insect drawers for pest control so can't vouch for their effectiveness or advisability of doing so since neither product are labelled for such use.

Image courtesy of Julieta Brambila, USDA APHIS PPQ, Bugwood.org

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