How to Manage Pests

UC Pest Management Guidelines


Relative Toxicities of Insecticides and Miticides Used in Corn to Natural Enemies and Honey Bees

(Reviewed 1/06, updated 8/08, corrected 3/19)

In this Guideline:

Common name (trade name) Mode of action1 Selectivity2 (affected groups) Predatory mites3 General predators4 Parasites4 Honey bees5 Duration of impact to natural enemies6
Bacillus thuringiensis ssp. aizawaii 11A narrow (caterpillars) L L L II none
Bacillus thuringiensis ssp. kurstaki 11A narrow (caterpillars) L L L III none
carbaryl (Sevin) 50, 80 1A broad (insects, mites) L/H H H I long
carbaryl (Sevin) XLR 1A broad (insects, mites) L H H I long
carbaryl (Sevin) XLR Plus 1A broad (insects, mites) L H L I long
carbaryl (Sevin) carbaryl bait 1A L L L III short
clothianidin (Poncho) 4A narrow (soil insects) I
dimethoate (Cygon) 1B broad (insects, mites) H H H I long
disulfoton (Di-Syston) 1B broad (insect, mites) H H H II
endosulfan (Thiodan) 2A broad (insects, mites) L M M II short
esfenvalerate (Asana) 3A broad (insect, mites) H M H I moderate
indoxacarb (Avaunt) 22A narrow (caterpillars) L L I moderate
malathion 1B broad (insects, mites) H H H I moderate
methomyl (Lannate) 1A broad (insects, mites) H H H I moderate
methoxyfenozide (Intrepid) 18 narrow (caterpillars) L L L II none
permethrin (Ambush, Pounce) 3A broad (insects, mites) L H H I long
petroleum oils un broad (exposed insects, mites) L L L II short to none
propargite (Comite) 12C narrow (pest mites) M7 L L III short
spinetoram (Radiant) 5 narrow (caterpillars, thrips, aphids) L M8 L/M II moderate9
spinosad (Entrust, Success) 5 narrow (caterpillars, thrips, aphids) L M8 L/M II short to moderate8
spiromesifen (Oberon) 23 narrow (mites) II
thiamethoxam (Cruiser)&–seed trt. 4A narrow (seedcorn maggot, wireworms) NA short to none
H = high      M = moderate     L = low    — = no information     un = unknown or uncertain mode of action     NA = not applicable
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at
2 Selectivity: Broad means it affects most groups of insects and mites; narrow means it affects only a few specific groups.
3 Generally, toxicites are to western predatory mite, Galendromus occidentalis. Where differences have been measured, these are listed as pesticide-resistant strain/native strain.
4 Toxicities are averages of reported effects and should be used only as a general guide. Actual toxicity of a specific chemical depends on the species of predator or parasite, environmental conditions, and application rate.
5 Ratings are as follows: I—Do not apply or allow to drift to plants that are flowering; II—Do not apply or allow to drift to plants that are flowering, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations; III—No bee precaution, except when required by the pesticide label or regulations. For more information about pesticide synergistic effects, see Bee Precaution Pesticide Ratings.
6 Duration: Short means hours to days; moderate means days to 2 weeks; and long means many weeks or months.
7 Use lowest rates for best management of western predatory mite/spider mite ratio.
8 Toxic against some natural enemies (predatory thrips, syrphid fly and lacewing larvae, beetles) when sprayed and up to 5-7 days after, especially for syrphid fly larvae.
9 Residual is moderate if solution is between pH of 7 to 8.



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Corn
UC ANR Publication 3443

General Information

Acknowledgements: This table was compiled based on research data and experience of University of California scientists who work on a variety of crops and contribute to the Pest Management Guideline database, and from Flint, M.L. and S.H. Dreistadt. 1998. Natural Enemies Handbook: An Illustrated Guide to Biological Pest Control, ANR Publication 3386.

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