-4- 



both the adults and the developing brood of bees. Probably contaminated 

 nectar kills mainly adult bees but this may depend on the speed of klll» 



2» Direct contact with the pesticide during application. Primarily kills 

 the field bees but brood may die from neglect. Repeated applications may 

 seriously effect the colonies. 



3. Exposure to residues of pesticides that have high toxicity to bees. Under 

 some conditions, high mortality to adult bees results. There is a lack 

 of sufficient information to determine how serious the effects of such 

 exposures may be on the brood. 



4. Effects on brood . May be direct by poisoning , or indirect from starva - 

 tion or exposures to extremes of temperature . 



B. SUGGESTIONS FOR AVOIDING BEE POISONING: 



1. Proper timing . Do not spray plants that are attractive to bees during 

 bloom with materials known to be toxic to these insects. 



2* Spraying in the early morning or in the evening will reduce bee losses 

 since fewer will be exposed to direct contact with the pesticide. 



3. Do not use higher concentrations or more spray than is necessary, 



4o Avoid contamination of area where spraying equipment is filled, particular- 

 ly if there is an accumulation of water being visited by bees. 



5» Clipping or spraying with an herbicide to prevent bloom will reduce bee 

 losses if ground cover in area to be sprayed contains dandelions or other 

 weeds attractive to bees. 



6. Notify local beekeepers if extensive spraying is to be done; they may be 

 able to take measures to reduce bee losses. 



TOXICITY OF PESTICIDES TO HONEY BEES 



From Anderson and Atkins, 1958 California Agriculture 12 (12): 3-4 with modification 



Anderson and Atkins set up four groups of pesticides based on their varying 

 toxicities to bees. Much original information was presented, some of which was 

 obtained from laboratory experiments. Most of the more important materials were 

 also tested in the field. It must be emphasized that weather conditions in 

 California may influence the effects of most pesticides so as to give very 

 different results than we might obtain in the Northeast. 



1. Materials that are toxic to bees which should not be used if there is a 



possibility of bee poisoning at the time of treatment or within several 

 days thereafter: 



•Idrin dleldrin lead arsenate 



BHC ENOSBP (DN211) lindane 



calcium arsenate Guthion parathion 



chlordane heptachlor Sevln 

 Diazinon 



1 



