Imidacloprid: what it kills and what it harms
A systemic neonicotinoid that plants draw up from the soil into their stems, leaves and flowers, so one drench can protect a tree or shrub for months. It works on aphids, whiteflies, lace bugs, most soft scales and young lawn grubs. It is not a miticide and can make spider mites worse, it does not control cottony cushion scale or most armoured scales, and it reaches the nectar and pollen that bees and nectar-feeding beneficials eat. It lasts too long to pair with released parasitoid wasps.
Also sold or listed as: Merit, Marathon, BioAdvanced 12 Month Tree & Shrub Protect & Feed, Bonide IMI 1.47% Concentrate.
At a glance
- Active
- Neonicotinoid, IRAC group 4A (systemic)
- Residue
- Long: many weeks to months after a soil drench (UC IPM). The tree-and-shrub label claims up to 12 months' protection from one application.
- Lethal
- 1 of 5 beneficials
- Caution
- 2 of 5 beneficials
- Safe
- 2 of 5 beneficials
What it works on
- AphidsOn the label as a soil drench or a spray. The systemic drench takes one week to three months to spread through a plant, depending on its size.
- WhitefliesOn the label. Under glass, soil-applied imidacloprid is hard on Encarsia formosa, the wasp released against whitefly.
- Lace bugsOn the label as a drench or spray on ornamentals.
- Soft scalesUC IPM says it controls European elm scale and most soft scales.
- Armoured scalesSuppression only on the home labels. UC IPM says it does not control most armoured scales.
- Cottony cushion scaleDoes not control it. UC IPM says it may even cause outbreaks, and it is very toxic to the vedalia beetle that controls this scale.
- Japanese beetle adultsListed on the tree-and-shrub labels. Treat only after the plant has finished flowering.
- White grubsA preventive: it controls newly hatched grubs but, per Kentucky Extension, is not very effective on older grubs and is not recommended as a late-summer rescue. See the grub killer comparison.
- Spider mitesNo control. It is not a miticide, and in field studies it raised spider mite numbers on treated elms, boxwoods and hops.
Effect on beneficials
- Encarsia formosaFresh field-rate residues killed over 98% of adult wasps within 6 hours in a laboratory test, and in a separate test, leaves of systemically treated plants killed many of them, though only after 48 hours. Rated lethal (> 75 %) on those figures. UC IPM rates a soil drench moderate (M) for parasitoids but lasting many weeks, and its whitefly Pest Note names imidacloprid, especially as a foliar spray, as particularly disruptive to whitefly natural enemies. — Wang et al. 2019 (Pest Manag Sci); Prabhaker et al. 2011 (J Econ Entomol); UC IPM floriculture table 01/22; UC IPM Pest Notes 7401Lethal — high, over 75 %
- Aphidius colemaniUC IPM rates soil-applied imidacloprid moderate (M) for parasitoids, with impact lasting many weeks; mapped M → caution. In laboratory residue tests it shortened the wasps' lives and cut parasitism, though less sharply than spinosad. — UC IPM floriculture table 01/22; D'Ávila et al. 2018 (J Econ Entomol)Caution — moderate, 25–75 %
- Chrysoperla carneaSources disagree. UC IPM rates a soil drench low (L) for general predators, which would map to safe. But University of Minnesota work found that imidacloprid moving into the flowers of soil-treated plants cut green lacewing survival, and NPIC reports lower survival in lacewings that fed from treated plants. Rated caution on that conflict, not on a published class. — UC IPM floriculture table 01/22; Rogers et al. 2007 via Krischik et al. 2007 (Environ Entomol); NPIC 2010Caution — moderate, 25–75 %
- Phytoseiulus persimilisUC IPM rates soil-applied imidacloprid low (L) for predatory mites; mapped L → safe. In NC State laboratory tests it did not kill adults but cut their egg-laying and egg hatch. Safe for the predator is not safe for the crop: imidacloprid can raise spider mite numbers on treated plants. — UC IPM floriculture table 01/22; Ditillo et al. 2016 (J Econ Entomol)Safe — low toxicity, under 25 % effect
- Amblyseius cucumerisUC IPM rates soil-applied imidacloprid low (L) for predatory mites; mapped L → safe. A laboratory risk assessment found the field rate an acceptable risk to adult females. Cornell still warns that this mite can be sensitive to many neonicotinoids, so watch for sublethal effects. — UC IPM floriculture table 01/22; Cheng et al. 2018 (Ecotoxicol Environ Saf); Cornell IPM 2022Safe — low toxicity, under 25 % effect
No data never means safe: treat an unrated pairing as caution and try it on a small area first. See every product side by side →
How it works
Imidacloprid is a neonicotinoid (IRAC group 4A). It blocks the nerve receptors that carry signals in insects, and it binds more strongly to insect receptors than to those of mammals or birds. It is systemic: plants take it up through the roots or leaves and move it into the stems, leaves, flowers and fruit, so sap-feeding and leaf-chewing insects are poisoned as they feed. The tree-and-shrub label says it takes one week to three months to spread through a plant, depending on its size, and claims protection for up to 12 months. In soil it can last for months or years (NPIC).
It has clear gaps. UC IPM says it does not control most armoured scales or cottony cushion scale, and that it may cause outbreaks of cottony cushion scale. The home labels list armoured scale only as 'suppression'. It also does nothing useful against spider mites and can make them worse. After imidacloprid treatments of elms in New York's Central Park, spider mites rose to outbreak levels. Mites feeding on treated trees laid more eggs, and their insect predators were poisoned by eating exposed prey (Szczepaniec and colleagues, 2011). The same group found more eggs and more mites on treated boxwoods, persisting into a second year, and a 2025 Oregon study found more twospotted spider mites on hops sprayed in June, though the effect varied from year to year.
Using it
- Trees (drench)
- BioAdvanced 12 Month Tree & Shrub Protect & Feed (1.47%, EPA Reg. 92564-33): measure round the trunk at 4.5 ft and use 1 fl oz of product per inch of circumference in 1 gallon of water, poured at the base. Over 50 inches round, use 2 gallons.
- Shrubs and pots
- Same label: 3 fl oz per foot of shrub height in 1 gallon of water. Pots: 1 teaspoon for a 1-gallon pot up to 6⅔ tablespoons for a 20-gallon pot. Avoid flushing pots through for 10 days.
- Lawns (grubs)
- Bonide IMI 1.47% Concentrate (EPA Reg. 53883-205): 2–3 fl oz per gallon of water per 333 sq ft, then ½ inch of rain or irrigation within 24 hours. The label allows treatment from May to October, but University of Kentucky Extension times it before the eggs hatch, from mid-May to July, because it does little against older grubs.
- Spray
- Bonide IMI: 1½ teaspoons per gallon, repeated at 10–14-day intervals as needed, only before bloom or after all the petals have fallen.
- How often
- Tree-and-shrub drench: once a year. Lawns: once a season. Both labels cap it at 0.4 lb of imidacloprid per acre per year (0.3 lb on peaches under the Bonide label).
- Re-entry and harvest
- People and pets may go back once the treated area has dried. The BioAdvanced tree-and-shrub product is not for plants grown for food. The Bonide IMI label does allow sprays on apple, pear, plum, cherry and peach trees after petal fall: wait 7 days before harvesting apples, pears, plums and cherries (0 days for peaches).
Cautions
- Bees
- Label: "highly toxic to bees exposed to direct treatment or residues on blooming plants or weeds. Do not apply product to blooming plants or weeds if bees are foraging in the treatment area." Never apply it to linden, basswood or other Tilia. A soil drench still reaches the flowers: UC IPM warns that systemics move into nectar and pollen.
- Nectar-feeding beneficials
- Minnesota research found soil-applied imidacloprid moved into buckwheat flowers at levels that killed a parasitic wasp, and the same lab found treated flowers cut the survival of lady beetles and lacewings. In University of Florida work on oleander aphid control, it killed 80% of monarch caterpillars fed on milkweed treated two weeks earlier.
- Spider mite flare-ups
- Treated plants can carry more spider mites than untreated ones. Check leaves for stippling in the weeks after a drench. See twospotted spider mite.
- Vedalia beetles
- Where cottony cushion scale is the problem, UC IPM warns that imidacloprid does not kill the scale but is very toxic to the vedalia beetle that controls it, and that scale outbreaks have followed its use.
- Water and fish
- Label: toxic to aquatic invertebrates. Do not apply near lakes, streams or ponds, or on waterlogged soil. NPIC rates it slightly toxic to fish.
- People and pets
- Signal word CAUTION: harmful if swallowed or absorbed through the skin, and a moderate eye irritant. Keep children and pets off treated areas until they are dry.
- Where it is banned
- The BioAdvanced label bars sale and use in Nassau, Suffolk, Kings and Queens counties, New York.
Use instead
- Spider mites: release Phytoseiulus persimilis, or use horticultural oil or insecticidal soap
- Aphids under glass: Aphidius colemani held melon aphid as low as imidacloprid did in a North Carolina trial
- Whitefly under glass: Encarsia formosa, and keep imidacloprid out of the house
- Armoured scales such as euonymus scale: horticultural oil on the bark in winter, or soon after the crawlers emerge, with thorough coverage (UC IPM)
- Cottony cushion scale: leave it to the vedalia beetle
- Lawn grubs: count first, then choose by timing; see the grub killer comparison
Other products
Sources
EPA label, Merit 1.47% Insecticide Plus Fertilizer (BioAdvanced), Reg. 92564-33 (2026)
EPA label, IMI 1.47% Concentrate (Bonide), Reg. 53883-205 (2019)
UC IPM, Relative Toxicities of Pesticides Used in Floriculture and Nurseries (01/22)
UC IPM Pest Notes 7408, Scales (Kabashima & Dreistadt, 2014)
UC IPM Pest Notes 7410, Cottony Cushion Scale
UC IPM Pest Notes 7401, Whiteflies
NPIC, Imidacloprid General Fact Sheet (2010)
Szczepaniec et al., Imidacloprid causes outbreaks of spider mites on elm, PLoS ONE 6:e20018 (2011)
Szczepaniec & Raupp, Imidacloprid and Eurytetranychus buxi on boxwood, Exp Appl Acarol 59 (2013)
Woods et al., Imidacloprid timing and twospotted spider mite on hop, J Econ Entomol 118 (2025)
Wang et al., Selectivity of insecticides to Encarsia formosa, Pest Manag Sci 75:2716 (2019)
Prabhaker et al., Imidacloprid and thiamethoxam with natural enemies, J Econ Entomol 104:773 (2011)
D'Ávila et al., Spinosad, imidacloprid and lambda-cyhalothrin on Aphidius colemani, JEE 111 (2018)
Ditillo et al., Tomato insecticides and Phytoseiulus persimilis, J Econ Entomol 109:2298 (2016)
Cheng et al., Six insecticides and Amblyseius cucumeris, Ecotoxicol Environ Saf 161 (2018)
Krischik et al., Soil-applied imidacloprid in nectar kills Anagyrus, Environ Entomol 36 (2007)
Univ. of Kentucky ENT-10, Controlling White Grubs in Turfgrass (Potter & Potter, 1999)
Vásquez, Orr & Baker, Aphidius colemani vs imidacloprid on chrysanthemum, J Econ Entomol 99 (2006)
Mach et al., Insecticides, monarchs and oleander aphid on milkweed, Environ Entomol 53:648 (2024)
Drafted from the cited sources, then checked claim by claim against those sources on 23 September 2026.
Always follow the label. Labels are legally binding; this page is not.