# Can honey bees pick up pyrethroids left on leaves from mosquito sprays?



## colinpurrington (Sep 10, 2018)

I've been trying to find evidence that honey bees can pick up pyrethroids that might be dried onto leaf surfaces. Information is needed for a blog post I'm working on about mosquito-control companies (I'm not a fan). I'm wondering whether the pyrethroids might get onto bees in the early part of day when plants are covered with dew and when plant guttation is making leaf surfaces wet (i.e., the chemicals are in solution, not dried). Thanks for any help.


----------



## wildbranch2007 (Dec 3, 2008)

colinpurrington said:


> i.e., the chemicals are in solution, not dried


if the chemicals are in solution and not dried absolutely the bees can pick them up, if they are dried, less likely, and pyrethroids are sensitive to light and breakdown somewhat although the synthetic pyrethroids will kill for 4 days.


----------



## colinpurrington (Sep 10, 2018)

Thank you, Mike. So *dried* pyrethroids on a leaf surface will kill honey bees for 4 days? Or is that 4 days for everything? Also, any chance you could point me to a research article for that? I'm trying to find a reference so that I can back up my belief that mosquito sprays are harmful to honey bees even days later. It's for https://colinpurrington.com/2018/09/buzz-on-mosquito-sprays/.



wildbranch2007 said:


> ...synthetic pyrethroids will kill for 4 days.


----------



## wildbranch2007 (Dec 3, 2008)

can't remember where I found it, but they were spraying north of here and they guy with bee hives was in florida, I looked up the pesticide they were spraying which was a synthetic pyrethroid and it said 4 days. The info is in FB, so I might not be able to find it again. will try


----------



## wildbranch2007 (Dec 3, 2008)

can't find the exact same information but in our area they sprayed Kontrol 30-30
from my email to the person in the spray area from the information I found at I think it was Cornell or the state of NY

Kontrol 30-30 is pyrethiom it kills bees, the pbo has a half life of 8 hrs. synthetic pyrethium has a half life of 4 days, but if I remember correctly once it dries is less likely to affect the bees. 

so after drying it's less likely to kill bees, so if they sprayed at night as they did here you would expect few dead bees, from the person that was in the spray area.

Over last couple of days I have assessed the damage from the XXXXXX mosquito spraying. 
I left for vacation with 28 hives all stuffing and producing well. I came back to find a total of 7 full hive loses and 4 more in very bad condition. None have produced a drop off honey and some have less than a couple weeks ago.


----------



## colinpurrington (Sep 10, 2018)

Thanks, Mike. Sorry to hear about your hives. Terrible. What was the spray?


----------



## wildbranch2007 (Dec 3, 2008)

colinpurrington said:


> Thanks, Mike. Sorry to hear about your hives. Terrible. What was the spray?


not my hives, I'm not in the spray area, a person in the bee club.


----------



## SoylentYellow (Dec 10, 2013)

Apistan is a synthetic pyrethroid, and beeks put it inside the hive. Does it kill all the bees?

Not much light in there, and like many labels there is bee language "ENVIRONMENTAL HAZARDS
This product is toxic to honey bees if bees are exposed to direct application. However, dried
residues of this product are non-toxic to honey bees . Treat during non-foraging periods to
minimize adverse effects."

Label here: https://www.centralapiary.com/

Dosage is important to consider. Also this is a residual treatment, 6 weeks.


----------

