The great Palm weevil temp experiment

[Stevetoad]

In an effort to see how much cold these spawns of satan can handle I devised a very scientific experiment to preform in them. I caught 3 South American palm weevils put them each in a tube and placed one in my freezer at 0f, one in my refrigerator at 35f and one in a cooler with ice and salt and was able to hold the temperature between 26-28f. Here are the results…

freezer at 0f for 1 hour (dead)

refrigerator at 35f for 12 hours (alive) 40 hours (alive)

salt / ice at 26-28f for 12 hours (alive) 40 hours (still alive) 

not a great outcome being that those temps would do a bunch of damage on its own.  
 

 

 

 

[tinman10101]

i love experiments steve.  the analyst in me is perplexed why your salt below 32F did not kill the beetle.  i guess there are many variables including sustaining the temps at 26-28F and not all beetles are created equal comes to mind or possibly your freezer is set to way below 0F (ie ... <26F).  regardless, cool experiment and sad that you have that many in your yard to participate in your experiment.  i live north of LA and just anticipating the gradual migration northwards.  

[LJG]

Things are ridiculously resilient. In some of my traps, then I forget to put a killing agent in the water they swim for seven plus days before finally dying and drowning.

[Stevetoad]

52 minutes ago, tinman10101 said:

i love experiments steve.  the analyst in me is perplexed why your salt below 32F did not kill the beetle.  i guess there are many variables including sustaining the temps at 26-28F and not all beetles are created equal comes to mind or possibly your freezer is set to way below 0F (ie ... <26F).  regardless, cool experiment and sad that you have that many in your yard to participate in your experiment.  i live north of LA and just anticipating the gradual migration northwards.  

Unfortunately they are on the way. one of my shops is in Mission Viejo and I have seen the evil weevil damage as far up as san Clemente and that's without actively looking around.  You can see some damaged CIDP in the Cristianitos creek by trestles.  

in hindsight the freezer is. a bit of a stupid test as those temps would kill a palm outright anyway.  The 26-28f falls inline with what my yard has seen as its record low so im a bit upset that there wasn't death. Im sure the weevils nuzzle into a warmer area too. 

 

[Stevetoad]

3 minutes ago, LJG said:

Things are ridiculously resilient. In some of my traps, then I forget to put a killing agent in the water they swim for seven plus days before finally dying and drowning.

You're not kidding. Ive had them eating the apple chunks fully submerged. In my area they took out a CIDP and now there is a queen and a washy that have collapsed crowns that are no more than 5o yards from the CIDP stump. It may be a coincidence but it's awfully fishy and concerning if true. 

[Than]

There must be some virus or fungus that kills them. If we could find one and infect some of them and release them to spread the disease it would be awesome. Or perhaps some mutation that makes them unable to dig, dunno... God I hate them so much!

[ZPalms]

What is there is actual role where they are from? how could palms exist period if they exist?

[Phoenikakias]

Ok let me please share an impression regarding the very similar rpw. I think that its activity and/or reproduction rate decreases considerably with increased air moisture combined with high temps.  I have witnessed countless times palms growing side by side one exposed to full sun and the other under canopy and former being infested and killed, while latter was remaining at laest seemingly  healthy.  Perhaps this is one of the reasons that tropics are still full of palms.

[Phoenikakias]

3 hours ago, Than said:

There must be some virus or fungus that kills them. If we could find one and infect some of them and release them to spread the disease it would be awesome. Or perhaps some mutation that makes them unable to dig, dunno... God I hate them so much!

There are the nematodes already, which are both outrageously expensive and difficult to storage and application.

[Silas_Sancona]

21 hours ago, Stevetoad said:

in hindsight the freezer is. a bit of a stupid test as those temps would kill a palm outright anyway.  The 26-28f falls inline with what my yard has seen as its record low so im a bit upset that there wasn't death. Im sure the weevils nuzzle into a warmer area too. 

 

Far from a stupid experiment Steve..  what you did falls in line with some of the first steps anyone looking into such aspects would do, then build upon later. 

Not saying something like this hasn't been done, at the lab - level,  already,  but,  don't think i've seen such info out there yet so ..Basic?  perhaps   ..but quite  an insightful first step into understanding how these  ..and/or  any other significant " pest " organism... would respond to a serious stress factor that you ..or anyone else in a similar area..  could experience while cultivating a vulnerable host plant. .  

Being tough- shelled, i'd figure these would be reasonably tough Beetles but, after 30... hours exposed to cold, figured they might not be that tough   ..which is eye opening..


And yes, as you mention, any adults flying around at the time would likely find some warm spot to hang out in to weather a couple chilly nights if need be.  Larvae would be tucked deep within a palm's trunk / crown,  thus avoiding being killed   ..unless it got cold enough to kill the palm itself ...which would defeat trying to save the palm anyway. 

[aztropic]

PLEASE don't export them to Arizona...🤦 Most of the big box stores and Moon valley stocks come from So CAL... When crossing the border headed west between Arizona and California, there is a no negotiation border check point entering California. Used to be in Arizona laws too, but not anymore... 5,4,3,2,1 💥

 

aztropic 

Mesa, Arizona 

[Stevetoad]

8 hours ago, aztropic said:

PLEASE don't export them to Arizona...🤦 Most of the big box stores and Moon valley stocks come from So CAL... When crossing the border headed west between Arizona and California, there is a no negotiation border check point entering California. Used to be in Arizona laws too, but not anymore... 5,4,3,2,1 💥

 

aztropic 

Mesa, Arizona 

Hmm maybe a heat test will be next. 120f ???? I caught 13 today and had one bounce off my arm while taking the trap down so I have plenty of subjects. 

[Tomas]

Here is some information provided by AI Mode by Google:

The primary scientific sources and findings include:

 

1. Lethal Thresholds by Biological Stage

Research conducted by institutes such as the CSIC (Consejo Superior de Investigaciones Científicas) and published in journals like IntechOpen indicates that different life stages have different survival limits:

• Neonatal larvae: Die if monthly average temperatures drop below 10.3 °C.
• Mature larvae and Pupae: Show "remarkable cold tolerance," with recorded lethal temperatures reaching 0 °C or slightly below (-2.3 °C).
• Adaptation mechanisms: Recent studies on PubMed Central demonstrate that the weevil produces cryoprotectant substances (such as glucose and glycerol) to prevent freezing damage, allowing survival during sudden cold snaps.

 

2. The "Insulation and Fermentation" Effect

The figure of -10 °C / -12 °C for several consecutive days is frequently cited by applied entomology experts as the threshold for natural population eradication (rather than just individual deaths). The reasoning is physical:

• Internal Microclimate: Inside the trunk, the temperature is significantly higher than outside. Research available via Scribd and Academic Journals has measured internal temperatures between 30 °C and 40 °C even in winter, thanks to heat generated by decomposing tissues and larval metabolic activity.
• Thermal Inertia: For the "heart" of the palm to reach the lethal temperature of 0 °C or lower (necessary to kill protected larvae), the external ambient temperature must drop drastically below -10 °C for multiple consecutive days to overcome the thermal insulation provided by the plant fibers.

 

3. Geographical Evidence (Japan and Northern Europe)

The case of Japan, documented in publications on ResearchGate, confirms that the weevil struggles to overwinter in areas where winter temperatures are consistently below freezing, but survives where frost spells are brief.

In summary, -12 °C is not the instantaneous death temperature for the insect in open air, but rather the environmental condition required for the cold to penetrate the palm's thermal sanctuary

[Rick Kelley]

On 1/30/2026 at 8:00 PM, Than said:

There must be some virus or fungus that kills them. If we could find one and infect some of them and release them to spread the disease it would be awesome. Or perhaps some mutation that makes them unable to dig, dunno... God I hate them so much!

Lots of factors to consider here-

In their native habitats, these insects are almost certainly preyed upon by numerous small mammals and reptiles that constantly dig through the decaying leaf litter on the forest floor looking for juicy grubs to eat.

Hungry monkeys and large birds are perpetually searching the canopy for tasty insects to eat. Mix in occasional dry spells, storms, fires, etc., and on average roughly two eggs per female weevil survive to adults that successfully lay a new generation of eggs. The population fluctuates from year to year and with seasons, but stays well below the burden that would kill all the palms in a region. Just like zebra populations persist for thousands of generations despite the constant losses from lions.

When ANY new species is introduced into a foreign ecosystem, all hell is likely to break out until some new equilibrium is reached, maybe hundreds of years down the road. The man-made examples are too numerous to list. In the case of weevils, if a female can lay 100 eggs, most will develop into adults in California because suburban landscapes lack the networks of small animals which might control grub populations. Going from 2 to 100 offspring per female explains the explosive spread of new pests in a predator-free environment.

Palm growers want a method to drive weevils to extinction, at least around their property. That is a very tall order. Farmers and ranchers have been looking for such solutions for many years for a horror show of insect pests. There are only a few success stories. The screwworm was eliminated from Texas cattle herds decades ago by releasing billions of radiation-steriled male flies. That achievement relied on a specific aspect of their mating behavior, so does not work for many other insect pests. The corn borer and rootwroms attacking America’s corn crop have been mostly defeated by planting only genetically modified seed that makes the Bt toxin. Something like this is not practical to protect hundreds of ornamental palm species, besides the fact that GMO methods are highly controversial.

Potentially more effective, and definitely far more controversial, is the use of CRISPR Gene Drive technology. This uses DNA editing technology to insert a toxic gene cassette into some insect pest, such as a weevil. The new genes either kill or sterilize one sex, usually females. The gene drive part of the technique forces 100% of the sons to inherit the trait, rather than only 50% expected in ordinary Mendelian Genetics. When such males are released, they mate with normal females which produce exclusively gene drive sons. Generation after generation the CRISPR cassette spreads through the wild population until at the end only males are left. Then the population collapses. Some gene drive mosquitos have been produced in the lab for species that spread terrible diseases, but worries over unintended consequences have prevented release. Genetic research into beetles is far behind flies and mosquitos, but some day it might be an option.

 

 

[Silas_Sancona]

6 minutes ago, Rick Kelley said:

 

Lots of factors to consider here-

In their native habitats, these insects are almost certainly preyed upon by numerous small mammals and reptiles that constantly dig through the decaying leaf litter on the forest floor looking for juicy grubs to eat.

Hungry monkeys and large birds are perpetually searching the canopy for tasty insects to eat. Mix in occasional dry spells, storms, fires, etc., and on average roughly two eggs per female weevil survive to adults that successfully lay a new generation of eggs. The population fluctuates from year to year and with seasons, but stays well below the burden that would kill all the palms in a region. Just like zebra populations persist for thousands of generations despite the constant losses from lions.

When ANY new species is introduced into a foreign ecosystem, all hell is likely to break out until some new equilibrium is reached, maybe hundreds of years down the road. The man-made examples are too numerous to list. In the case of weevils, if a female can lay 100 eggs, most will develop into adults in California because suburban landscapes lack the networks of small animals which might control grub populations. Going from 2 to 100 offspring per female explains the explosive spread of new pests in a predator-free environment.

Palm growers want a method to drive weevils to extinction, at least around their property. That is a very tall order. Farmers and ranchers have been looking for such solutions for many years for a horror show of insect pests. There are only a few success stories. The screwworm was eliminated from Texas cattle herds decades ago by releasing billions of radiation-steriled male flies. That achievement relied on a specific aspect of their mating behavior, so does not work for many other insect pests. The corn borer and rootwroms attacking America’s corn crop have been mostly defeated by planting only genetically modified seed that makes the Bt toxin. Something like this is not practical to protect hundreds of ornamental palm species, besides the fact that GMO methods are highly controversial.

Potentially more effective, and definitely far more controversial, is the use of CRISPR Gene Drive technology. This uses DNA editing technology to insert a toxic gene cassette into some insect pest, such as a weevil. The new genes either kill or sterilize one sex, usually females. The gene drive part of the technique forces 100% of the sons to inherit the trait, rather than only 50% expected in ordinary Mendelian Genetics. When such males are released, they mate with normal females which produce exclusively gene drive sons. Generation after generation the CRISPR cassette spreads through the wild population until at the end only males are left. Then the population collapses. Some gene drive mosquitos have been produced in the lab for species that spread terrible diseases, but worries over unintended consequences have prevented release. Genetic research into beetles is far behind flies and mosquitos, but some day it might be an option.

 

 

  Could not have put this into a more perfect context.. 

FYI, as you may have heard,  Screw worms are trying to make a comeback atm across Mexico..



While having them around to take out X 100's+ -amount of palms right now  sucks ______ = insert your own word there..   these Weevils have been present in both Mexico / Baja,  and Cen. America for ...quite some time  ..and there are plenty of vulnerable -to -this - specific -weevil palm species /genera still around down there..  

Plenty of Yucca,  Agave, and Cacti  still around  ..all of whom can attract attention from specific- to- them Snout Weevil sps / genera / other insect " pests ".. 

Nature will find the right balance in controlling SAPW,  where ever their range expands to next over time 

...That is if overly- fearful of letting nature do it's thing  humans don't kill all the bug eaters ..and themselves..  first.. 

 

[Phoenikakias]

8 hours ago, Rick Kelley said:

 

Lots of factors to consider here-

In their native habitats, these insects are almost certainly preyed upon by numerous small mammals and reptiles that constantly dig through the decaying leaf litter on the forest floor looking for juicy grubs to eat.

Hungry monkeys and large birds are perpetually searching the canopy for tasty insects to eat. Mix in occasional dry spells, storms, fires, etc., and on average roughly two eggs per female weevil survive to adults that successfully lay a new generation of eggs. The population fluctuates from year to year and with seasons, but stays well below the burden that would kill all the palms in a region. Just like zebra populations persist for thousands of generations despite the constant losses from lions.

When ANY new species is introduced into a foreign ecosystem, all hell is likely to break out until some new equilibrium is reached, maybe hundreds of years down the road. The man-made examples are too numerous to list. In the case of weevils, if a female can lay 100 eggs, most will develop into adults in California because suburban landscapes lack the networks of small animals which might control grub populations. Going from 2 to 100 offspring per female explains the explosive spread of new pests in a predator-free environment.

 

 

 

 

8 hours ago, Silas_Sancona said:

  Could not have put this into a more perfect context.. 

FYI, as you may have heard,  Screw worms are trying to make a comeback atm across Mexico..



While having them around to take out X 100's+ -amount of palms right now  sucks ______ = insert your own word there..   these Weevils have been present in both Mexico / Baja,  and Cen. America for ...quite some time  ..and there are plenty of vulnerable -to -this - specific -weevil palm species /genera still around down there..  

Plenty of Yucca,  Agave, and Cacti  still around  ..all of whom can attract attention from specific- to- them Snout Weevil sps / genera / other insect " pests ".. 

Nature will find the right balance in controlling SAPW,  where ever their range expands to next over time 

...That is if overly- fearful of letting nature do it's thing  humans don't kill all the bug eaters ..and themselves..  first.. 

 

I fear it ain't that simple. In the Mediterranean native fauna in most cases adapts quit fast to new food sources. We know that magpies and jays prey on the larvae of rpw, even cats have been occasionally observed to eat an adult beetle. Here magpies even feed regularly on the fruits of Livistona chinensis, tiny birds on the petals if the Feijoa flowers and unidentified creatures on the fruits of Chamaedorea. Below there is a video of jays feeding on the rpw larvae in the crown of a CIDP. Nevertheless no one can yet claim, that the pest has been brought to some kind of balance.

 

[Silas_Sancona]

32 minutes ago, Phoenikakias said:

 

I fear it ain't that simple. In the Mediterranean native fauna in most cases adapts quit fast to new food sources. We know that magpies and jays prey on the larvae of rpw, even cats have been occasionally observed to eat an adult beetle. Here magpies even feed regularly on the fruits of Livistona chinensis, tiny birds on the petals if the Feijoa flowers and unidentified creatures on the fruits of Chamaedorea. Below there is a video of jays feeding on the rpw larvae in the crown of a CIDP. Nevertheless no one can yet claim, that the pest has been brought to some kind of balance.

 

Birds in your vid look like Hooded Crows or Jackdaws  rather than your local subsp. of Eurasian Jay..











Regardless,  if your local birds / other insect eating animals are dining on them, they're doing their part to balance the scales..

Have little doubt our local Corvids,  ...and other bug eaters... are also out there consuming their fair share of SAPW adults and grubs now available to their diet,  just as their relatives further south have been doing since this quick < and tasty > SAPW protein source evolved.

 

[Phoenikakias]

1 hour ago, Silas_Sancona said:

Birds in your vid look like Hooded Crows or Jackdaws  rather than your local subsp. of Eurasian Jay..











Regardless,  if your local birds / other insect eating animals are dining on them, they're doing their part to balance the scales..

Have little doubt our local Corvids,  ...and other bug eaters... are also out there consuming their fair share of SAPW adults and grubs now available to their diet,  just as their relatives further south have been doing since this quick < and tasty > SAPW protein source evolved.

 

Indeed they are hoodies, wrong translation.

[Tomas]

AI Mode again:

The collapse of the crown (the palm "opening up" like an inverted umbrella) is the final stage of an infestation that began months, if not years, earlier. This is why the natural protection and the adult's armor are so effective:

• The "Trojan Horse": By the time symptoms become visible to the human eye, the trunk is already an "insect factory." Several generations have already succeeded each other inside (a complete cycle lasts about 3–4 months).
• Protected Pupation: Mature larvae never expose themselves. They build a very sturdy cocoon made of interwoven palm fibers, located right at the base of the petioles (the leaf bases). This cocoon protects the pupa not only from predators but also from superficial chemical treatments, as noted in studies on IntechOpen - Red Palm Weevil Management.
• Invisible Flight: Newly emerged adults leave the cocoon and can remain inside the plant to mate again or fly away to a new palm. When the palm "collapses" and exposes its interior, most of the "pioneer population" is already gone.
• The Late Banquet: Birds or rodents that arrive when the palm is open only find the "leftovers" of an already completed infestation or the larvae of the last wave—too late to save the plant or stop the spread to the neighborhood.

Essentially, the palm acts as a perfect thermal and mechanical shield. This is why today's efforts focus entirely on early diagnosis (using acoustic sensors to "listen" to larvae chewing or thermography) to intervene while the crown is still upright