Return to the map ↩

Relative toxicity of pesticides

Honeybees react differently to different pesticides, and most herbicides and fungicides are less toxic to bees than are insecticides. To the beekeeper, the most obvious sign of pesticide poisoning is the presence of an exceptional number of dead bees in front of the hives. The following figures have been established as guidelines for assessing the extent of pesticide poisoning: 100 dead bees per day is the colony's normal death rate; 200-400 dead bees indicate a low level of pesticide poisoning; 500-1000 dead bees indicate a medium level of pesticide poisoning; over 1000 dead bees indicate a high level of pesticide poisoning.


As indicated above, pesticide application is one of the most important inputs to agriculture. Understanding and cooperation among growers and beekeepers are essential to prevent, or at least to minimize, the loss of honeybees due to the toxic effects of pesticides. The following table lists the most common pesticides, indicating their relative toxicity to honeybees.


Relative Toxicity of Pesticides to the Common Honeybee

Group 1 - Highly Toxic

The application of these pesticides to foraging areas when bees are active may cause severe damage. Beekeepers must know in advance when they are to be used and take special precautions; moving colonies out of the area temporarily is perhaps the safest approach.

aldrin Dimecron (phosphamidon) methyl parathion
arsenicals Methyl Trithion
Azodrin Ethyl Guthion (azinphosethyl) Mobam
Baygon Monitor
BHC Famothos(famphor) parathion
Bidrin Furadan Phosdrin (mevinphos)
Chlothion Guthion Sevin (carbaryl)
dimethoate heptachlor Sumithion
fensulfothion Imidan Temik (aldacarb)
DDVP (dichlophos) Lannate (methomyl) TEPP
diazinon lindane Zectran
Dibrom malathion Zinophos dieldrln

Group 2 - Moderately Toxic

These products should not he applied directly on fields when bees are actively foraging or when hives are exposed. Dose, timing and application methods are among factors determining whether the pesticides can he used with minimum risk to bees.

Abate endothion Perthane
Agritox endrin Phosalone
Banol Korlan (ronnel) Phosvel, Abor
Carzol (formetanate) MetaSystox Pyramat
(methyl demeton) Systox (demeton)
chlordane MetaSystox R (oxy-demeton-methyl) Thinet (phorate)
DDT Thiodan (endosulfan)
Di-Syston (disulfoton) mirex Trithion

Group 3 - Relatively Non-Toxic

These products can be used on fields or near hives with minimum damage to bees; in fact, a few of the listed acaricides can he used to control bee mites within the hive.


acaraben (chloro-benzilate) Ethodan Omite
Fundal OMPA (schradan)
Allethrin Galecron (chlorophenamidine) Ovotran (ovey)
Aramite Phostex
Bacillus thuringiensis Heliothis virus phrethrin
Kelthane (dicofol) Rhothane (TDC)
cryolite Kepone rotenone
Delnav (dioxathion) methoxychlor ryania
Dessin Mitox (chlorbenside) sabadilla
Dilan Morestan Sulphenone
Dylox (trichlorfon) Nemagon Tedion (tetradifon)
Eradex Neotran nicotine toxaphene


Arasan (thiram) Cyprex (dodine) Manzate (maneb)
Benlate (benomyl) Dexon Mylone
bordeaux mixture dichlone Parzate (nabam)
copper oxychloride sulfate Difolatan Phaltan (folpet)
Dithane M-45 Polyram
copper sulfate (monahydrate) (folcid) sulfur
Glyoxide (glyodin) Thynon (dithianon)
cuprous oxide Karathane (dinocap) Zerlate (ziram)


amitrol Eptam (EPTC) picloram
Ammate (ammonium sulfamate) Folex (merphos) Planavin
Herbisan (EXD) Princep (simazine)
atrazine Hyvar (bromacil) Randox (CDAA)
Banvel (dicamba) Igran (terbutryne) Sinbar (terbacil)
Betanal (phenmedipham) IPC Stem F-34 (propanil)
Karmex (diuron)
Caparol (promytryne) MCPA TOK (nitrofen)
Casoron (dichlobenil) Milogard (propazine) Trysben (2,3,6-TBA)
monuron Vegedex (CDEX)
dalapon NPA 2,4-D
DEF paraquat 2,4-DB
diquat   2,4,5-T