Flea Beetles

Table of contents

    Important Tips for Best Management

    • Seed into a warm, moist seedbed to promote good stand establishment and rapid seedling growth as this will allow the crop to outgrow the susceptible stage (up to the 4-leaf stage) sooner, resulting in a shorter time period for  damage (since most injury occurs between the cotyledon to early true leaf stage). Conditions that slow canola development allow the flea beetles a longer time to feed before the plant surpasses the susceptible stage. After the fourth leaf stage there will be minimal impact on yield.[1]
    • An insecticidal seed treatment is provided in western Canada by every canola seed supplier and can provide good levels of protection. Additional seed treatment offerings may provide enhanced or additional insect control.
    • Scout fields in the spring. Assess damage to cotyledons and the first true leaves of seedlings daily, as well as the stems and the undersides of leaves. If leaf area loss is below thresholds, but flea beetles are present in high numbers and the crop is not advancing, stem feeding may be the reason. Continue to scout until the seedlings are past susceptibility, especially when temperatures exceed 14°C and new feeding continues. When scouting note that time of day and weather can influence flea beetle activity. On rainy or cool days, flea beetles will usually take cover; these conditions may encourage damage to stems or under leaves, or  even stop feeding temporarily. Rain can also help the crop more quickly recover (in moisture limiting situations).
    • The action threshold for applying foliar insecticide is typically at 25% leaf area defoliation, if flea beetles are still present and actively feeding. For crops with very low plant populations this threshold may be lower.
    • Predators, parasites and diseases can be important in regulating insect populations. However, flea beetles emerge in large numbers during a short period of time so they tend to overwhelm the limited number of parasites and predators that attack them.
    • Cultural control methods can help reduce flea beetle damage:
      • Less favourable microclimate (ex. standing stubble or presence of residue) in direct seeded crops may reduce injury.
      • Seed canola as early as practical to maximize seed yield.
      • Increasing seeding rates can help reduce the impact of flea beetle damage.
      • For a given seeding rate, some research has demonstrated less flea beetle damage per plant for canola grown in 12" row spacing vs. narrower spacing. [31]
      • When flea beetle populations are very high, no cultural controls will effectively reduce their attack.

    About Flea Beetles


    Flea beetles (Coleoptera: Chrysomelidae) feed on plants of the mustard family (Brassicaceae) grown across Canada and throughout the Northern Great Plains of North America (which includes up to the Peace River region of the Canadian Prairies). Eight flea beetle species are known to attack canola, mustard and rapeseed.

    Crucifer, Striped and Hop Flea Beetles

    Three main species attack canola in western Canada:

    • Crucifer flea beetle - Phyllotreta cruciferae (Goeze)
    • Striped flea beetle - Phyllotreta striolata (F.)
    • Hop flea beetle - Psylliodes punctulata Melsh.

    The crucifer flea beetle and the striped flea beetle were both introduced from Eurasia, and are significant pests. Traditionally, striped flea beetles have been more common in the northern areas of Canada and crucifer flea beetles have been more common in the southern areas and have been the most prevalent species in western Canada. The range and the population of the striped flea beetle has increased notably in the last few decades, with it becoming the most frequently encountered flea beetle species in central Alberta, central Saskatchewan and much of Manitoba. [53][57] However the predominant flea beetle species found in fields with high number of flea beetles is still crucifer. [53] The hop flea beetle is a native species that occurs in low numbers throughout the prairies. [2][3]

    The economic impact of flea beetles on crop production varies with population densities. Yield losses of about 10% are common where flea beetles are abundant even when the crop is protected with insecticides. [4],[5]  A 1% per acre yield reduction results in a total crop loss of about $25 million to $35 million. Annual crop losses in North America from flea beetles probably exceed $300 million. [6]

    Life Cycle

    Flea Beetle Life Cycle

    Flea beetles have one generation per year in western Canada, although adults appear twice during the growing season. In the spring, overwintered adults emerge and feed on canola seedlings. In the fall, it is the adult offspring of those overwintering adults that are observed feeding on canola leaves, stems and seed pods.

    Flea beetles overwinter as adults near the surface of the leaf litter, grass and debris beneath hedges, shelterbelts, poplar groves and in association with canola stubble and volunteer cruciferous plants. Within the leaf litter flea beetle densities may be as high as 140 to 250 beetles/m2.

    Adult flea beetle in spring leaf litter

    Flea Beetle Larvae

    Adult flea beetle feeding on pods and stems

    Flea beetles become active with the first extended period of warm weather in April and May, 5 to 11 days after leaf litter begins to thaw in the spring. Depending on temperature, it may take an additional three weeks before all the overwintering adults emerge.

    Emergence timing:  Hops => Striped=> Crucifer

    Hop flea beetle adults emerge about 10 days earlier than those of striped flea beetle, with the striped flea beetle emerging 1 to 4 weeks earlier than the crucifer flea beetle. [7]  Peak emergence of the crucifer flea beetle occurs when ground temperatures reach 15°C. [8]

    Under cool conditions, flea beetles walk or hop into the adjacent cruciferous crops or weeds. They feed on volunteer canola and mustard, or on weeds such as wild mustard, flixweed, lamb's quarters, stinkweed or peppergrass. Then they will move to newly emerged canola seedlings. When air temperatures exceed 14°C and winds are calm they will fly, dispersing throughout the field and invading other fields, attacking seedlings as they emerge. [9],[10]

    After feeding has commenced, beetles mate repeatedly. Egg-laying begins in late May and continues for about 30 days. [6],[8]  Some egg laying may continue until early August. Females deposit about 100 smooth, yellow, elongated, oval eggs 0.38 to 0.46 mm (0.01 to 0.02") by 0.18 to 0.25 mm (0.006 to 0.009") wide, either singly or in groups of three or four in the soil adjacent to the host plant's roots. [8] Eggs must be in contact with moist soil, or they desiccate within a few hours. The eggs take about 12 days to hatch. After egg laying the overwintering adults die off.

    Flea beetle larvae are grub-like with off-white bodies and a brown head and anal plate. Larvae moult twice during 25 to 34 days, completing three larval stages usually mid-June to late July. Full-grown larvae are about 3 to 4 mm (0.1 to 0.2") long.

    Larvae feed on the root hairs and taproots of seedlings. In a few cases, larvae have been observed burrowing into the plant near the juncture of the root and stem. When larval development is complete, larvae pupate in small earthen cells.

    Flea beetle pupae are usually present in the field by early to mid-July. They are entirely white except for the eyes, which darken as the pupal stage progresses to completion. The body appendages are free and distinguishable. The pupal stage lasts for about seven to nine days.

    Adult emergence begins after mid-July and continues until October. [11] The beetles feed on the leaves, stems and pods of cruciferous plants. Development from egg to adult takes about seven weeks. In late August and September, adults move into leaf litter and debris to overwinter.

    Influence of Environment

    Sunny, warm, dry weather increases feeding activity. Cool, damp weather slows flea beetle activity (and may drive them down to the stems where they may feed, or the undersides of the leaves), but they tend to survive fairly well in spite of the reduced activity level. If the weather warms up, growers should continue to scout for damaging levels of flea beetles.

    Identify flea beetles

    Flea beetles attacking canola, mustard and rapeseed are small, elliptical or oval-shaped and less than 2.5 mm (0.1") long. When disturbed they use their powerful hind legs to jump away like a flea - hence, the name flea beetle.

    Scouting techniques

    Adult flea beetle on cotyledons

    Spring flea beetle populations and damage levels are unpredictable, but scouting and observing flea beetle densities in the fall can potentially provide some indication of populations the following spring.

    Heavy infestations can severely damage cotyledons, the first leaves, petioles and stems. Crop thinning and delayed crop development caused by flea beetle feeding are most severe the first two weeks after seedling emergence.  Damage is most evident under poor growing conditions with limited crop growth; typically dry seedbed conditions and  warm weather speeding up insect feeding. At the 3-leaf or 4-leaf stage, the plants are established and can generally outgrow the feeding damage. At this time, adult flea beetle numbers often begin to decline. The crop can usually compensate provided plant counts are adequate and large portions of the crop are not totally destroyed.

    Feeding damage is most severe when flea beetles attack the growing point, limiting the plants' ability to re-grow. Heavy attacks can destroy the entire crop, forcing growers to reseed or leave the field fallow. During windy, cold, inclement weather and periods of slow plant growth, flea beetles can feed on seedlings at or near the soil surface. This stem feeding reduces the plant’s ability to supply water to the leaves and particularly under hot, dry conditions can result in seedling death. While stem feeding isn’t normally common, examining the canola cotyledon stems for damage when leaf feeding is occurring is an additional recommended scouting technique. No specific threshold exists to assist growers in evaluating the impact of stem feeding, but due to the function of the stem and its fragility when young, only low levels of feeding are required on new stems to cause plant fatality. However, seedlings that die from this are hard to find and seedling death could easily be confused with various other reasons, including cutworms, frost and seedling diseases.

    Severe flea beetle feeding damageNote: Seedling loss from plant disease can be mistaken for flea beetle damage. Dig damaged plants from the soil and examine carefully for evidence of disease on the shoots and roots. Consider marking individual plants (ex. by placing a brightly-coloured washer around them) while scouting to identify damage causes and severity.

    Delayed maturity from early flea beetle damage can expose the crop to adverse temperatures during flowering or to frost before the plants have matured. Uneven maturity at harvest reduces seed quality or yield. Delaying harvest to allow immature pods to ripen contributes to yield loss when over-ripe pods shatter during harvest. Harvesting too early can produce a crop with many immature seeds containing high chlorophyll levels, affecting seed quality and yield. Most of this damage can be prevented if canola is protected from flea beetle injury during the two to three weeks following emergence.

    Flea beetles that emerge after mid-July can also affect yield. Heavy feeding during pod development and filling causes injury to pods, leading to premature pod drying, shriveled seeds, pod shattering, increased chlorophyll content, and encourages fungal growth within the pods during damp weather. Injury to the pods is usually concentrated on the youngest pods and on late seeded crops. Yield is not usually affected when the crop has matured to at least the stage when seeds in the lower pods have turned from translucent to green.

    Minimize infestations

    Natural enemies and biological control

    Predators, parasites and diseases can be important in regulating insect populations. To date the effect of biological control agents seems to be limited but several insects have been observed attacking adult flea beetles.

    The flower beetle, Collops vittatus (Say) [18], big-eyed bug, Geocorus bullatus (Say)  [19], damsel bugs (Nabis spp.) [20], field crickets (Gryllus pennsylvanicus Berm.) [21] and lacewings (Chrysopa spp.) play a minor role in controlling flea beetles.

    The native braconid wasp (Microctonus vittatae Muesebeck) parasitizes flea beetle adults and is widespread across the prairies. [22] However, parasitism by the wasp usually averages less than 5% of the flea beetle population. [23],[24]

    Townesilitis bicolor (Wesmael), a braconid wasp that occurs in central Europe, was found to parasitize up to 50% of the crucifer-feeding flea beetles there. [25] This wasp was imported and released in Manitoba in multiple introductions from 1978 to 1983 but did not become established for unknown reasons.

    Isolates of entomopathogenic nematodes that are promising candidates for the biological control of P. striolata under field conditions have been recently found in China. [26]

    Unfortunately, flea beetles emerge in large numbers during a relatively short period of time and tend to overwhelm the parasites and predators.

    Flea Beetle Management

    Agronomic practices that promote good stand establishment and rapid seedling growth will reduce the impact of flea beetles on canola yield. For example, targeting a plant stand of 5-8 plants per square foot should ensure that the crop can withstand some feeding prior to reaching a defoliation threshold. There are also several other management options which may impact flea beetles.

    Seed Treatment: All canola seed marketed in western Canada currently includes a group 4 neonicotinoid insecticide. Additional seed treatment offerings, including a group 28 insecticide (cyantraniliprole), are available at additional cost that show increased flea beetle activity and cutworm control. Striped flea beetle has shown to be more resistant to the effects of neonicotinoid seed treatment insecticides than crucifer flea beetles.[51] With seed treatments, feeding still occurs, as insecticide ingestion is required to control flea beetles. Prior to considering the addition of supplementary insecticide or biological seed treatment products, economic thresholds, expected plant stands, and anticipated damage levels should be considered (as well as cost). When feeding damage exceeds the action threshold, a foliar insecticide application should be considered to limit economic loss. See the insecticide control options section for more information.

    A practice that has been of interest to some growers and researchers from the standpoint of reducing cost and insecticide load on the environment is blending a proportion of seed without insecticide together with treated seed for planting. Under moderate levels of flea beetle damage, research has demonstrated that as much as one-third of planted seed could be untreated with insecticide without subsequent seed yield reduction. [48] However, this practice is currently not recommended because of the highly variable and unpredictable nature of flea beetle damage, and the potential for the use of farm saved seed for the "untreated" proportion which has other negative agronomic and legal risks. This strategy could be explored further in the future in conjunction with other integrated management strategies or with improved forecasting.

    Tillage: Flea beetles prefer bright relatively warm conditions. Direct seeding provides a microclimate that is less ideal for flea beetles than tillage before seeding. Planting into stubble may provide a microclimate that is cooler, moister and less favourable to flea beetles. Injury may be reduced due to the cooler microenvironment created by stubble shading on surface soil. Cooler temperatures at the soil surface slow flea beetle activity reducing damage. However, crop development can also be slowed by cooler temperatures, so frequent crop scouting is still essential to ensure damage thresholds are not exceeded.

    In Alberta, zero till canola production can reduce flea beetle damage to levels equivalent to those found with the use of insecticidal seed treatments. [31]

    Weed control in nearby fields can contribute to additional insect pressure/damage within your canola crop. Nearby fields may contribute additional flea beetles if weed control or tillage operations leave flea beetles looking for food sources before the crop passes the 4-leaf stage. Leaving a trap strip of volunteer canola near overwintering sites can be an effective control strategy if the trap strip is sprayed before beetles move into the canola crop, although this strategy can be difficult to implement successfully.

    Seeding Date: Producers are urged to seed canola as early as practical to maximize seed yield. Early seeding will maximize plant size before flea beetle emergence and the larger plants tolerate more injury. [32] One study completed in southern Alberta, canola planted in April has fewer flea beetles and suffers less damage than canola planted in May, while the opposite was true in central and northern Alberta. [33]

    Seeding Rate: Increasing seeding rates can help reduce the impact of flea beetle damage, because spreading the feeding damage over more plants per unit area means that feeding damage per plant is reduced and seedlings can recover more readily from flea beetle injury.

    Older research has shown damage to individual plants to be lower with a 10 kg/ha (8.9 lb/ac) seeding rate than with a 5.0 or 7.5 kg/ha (4.5 or 6.7 lb/ac) rate. [30] Higher seeding rates and plant densities are believed to dilute and reduce damage to individual plants. However, the benefits of higher seeding rates for flea beetle control need to be tempered by the costs, which include increased production costs and pesticide load to the environment, and the possibility of increased lodging and susceptibility to diseases. Seed costs can represent one of the single highest investments in the canola production year. Growers are well advised to prioritize all of their investments in trash management, seeding tools, genetics, additional traits and seed treatment costs on a field by field basis. In some cases, it will be difficult to determine if challenging seedbed conditions or anticipated insect pressure can be best managed by a different choice of crop, additional canola seed or enhanced seed treatment protection. Practices that encourage higher plant establishment rates such as slower seeding speeds, optimal planting depth, only safe rates of seed placed fertilizer can reduce the risk flea beetle damage poses by encouraging good crop establishment.

    Row Spacing: At a given seeding rate, row spacing of 20 to 30 cm (8 to 12") have been shown to result in less flea beetle damage per plant than 10 cm (4") row spacing. [31] Although the reasons are not yet clear, it appears that flea beetles are more attracted to the reduced visual contrast between vegetation and soil that occurs at narrow row spacing.

    Crop Rotation: Crop rotation is not an effective means of controlling flea beetles. Adults overwinter inside and outside of the cropped areas and are capable of long-range migration. While intercropping with non-host plants has reduced flea beetle damage in Brassicaceous vegetables, the benefits of field-scale intercropping of canola and wheat [34] or canola and field peas [35] currently are not sufficient to warrant their use as flea beetle management options.


    Resistance breeding

    Hairy canolaWhile no canola variety has resistance to flea beetle, some researchers have completed work aimed at developing resistance, since several studies have shown that flea beetles prefer certain crucifer hosts. [36],[37],[38]

    The lower levels of flea beetle feeding seen on yellow mustard seedlings compared to canola seedlings is likely due to an aversion to the levels of glucosinalbin in mustard seedlings and to seedling tolerance to feeding injury. [39],[40] Trichomes (leaf hairs) impart resistance to flea beetles in certain crucifers. [41],[42]

    Researchers have found canola germplasm with increased numbers of hairs on young true leaves displayed resistance to flea beetles in field trials [43],[44], in some cases surpassing the protection level provided by neonicotinoid seed treatments.  These hairs may have discouraged flea beetles from walking up hairy stems. Research continues on canola lines with further elevated numbers, lengths, and complexities of plant leaf hairs that may achieve levels of resistance to flea beetles at present seen only with insecticide use. 

    Reduce economic losses

    Economic and Action Thresholds

    Flea Beetles causing defoliation

    Use leaf defoliation levels to decide whether a foliar spray for flea beetle control will be economical. Since seed treatments are standard practice, the use of economic thresholds for flea beetle control in canola only apply when foliar sprays are being considered.

    Canola seedlings may withstand 50% leaf loss without significant yield penalty. However, the action threshold for flea beetle feeding on canola is actually when there is 25% defoliation and flea beetles are continuing to feed. The reason for this discrepancy is that leaf area loss can escalate very quickly (sometimes even over the course of a single day) in a severe flea beetle infestation from 25% (action threshold) to 50% (economic threshold). With increased defoliation, plant tissue damage over and above simple feeding results in progressively less green leaf material for flea beetles to eat and further increases the rate of crop damage. Numerous publications [54],[55],[56] refer to the 25% action threshold as the economic threshold in order to allow growers to proactively manage this aggressive insect pest. Therefore applying controls at 25% defoliation will reduce the risk of flea beetles reaching a level where yield loss and plant development are substantially reduced. Research to re-evaluate these thresholds found that canola with up to 25% leaf area loss will yield the same as canola with no leaf area loss at all.

    Action threshold: 25% defoliation
    Economic threshold: 50% defoliation

    Note that the action threshold of 25% and the economic threshold of 50% are based on previous optimal plant stand recommendation of 75 to 150 plants per square metre (7 to 14 plants per square foot) and older seed treatments. Growers should take plant stand and growing conditions into consideration when making economic threshold decisions. Read the current target plant population recommendations in the Plant Population section of the Canola Encyclopedia. 

    Thinner plant stands will require a foliar insecticide application at a lower defoliation percentage than an optimal plant stand, because in this situation maintaining plant health is more critical to maximize production per plant in order to compensate for reduced plant numbers. Any plant mortality is also more likely to directly impact yield when plant density is already lower or less uniform than optimal.

    Flea Beetles causing defoliationWhen assessing whether a foliar insecticide spray is needed, growing conditions, soil moisture, overall crop health, yield potential and commodity prices all need to be considered along with flea beetle numbers and damage (both to leaves and stems). Control decisions should be based on current defoliation and the potential for crop growth to exceed feeding by flea beetles going forward. If soil moisture and growing conditions support rapid canola growth and seedlings are vigorous, the crop may be able to stand more feeding than slow growing drought stressed canola. However, when flea beetle feeding is combined with poor plant growth during hot, dry weather, canola can tolerate less feeding than if plants are growing under more ideal growing conditions.

    Although it is the damage to the youngest tissue that is of immediate concern, the damage to the newest growth should be assessed to determine if feeding levels are decreasing or increasing.

    When scouting fields for flea beetle damage, it is important to understand that flea beetles generally invade canola fields from the field edges. Flea beetle damage and the number of flea beetles may be higher at the field edge than farther into the field. An insecticide application to field perimeters may control invading beetles if they have not spread throughout the field. On hot and calm days, flea beetles are capable of moving longer distances and may populate the field more uniformly.

    Flea beetle numbers can be very high in ripening canola in the fall. If crops are very late in maturity, extensive feeding on pods can lower yields and increase green seed content. However, seed yields are usually not affected when crop maturity is more advanced than growth stage 5.2, when the seeds in lower pods have turned from translucent to green. [45]

    Insecticide control options

    Canola, mustard and rapeseed crops can be protected from flea beetle attack through insecticide application as a seed treatment or post-emergence foliar sprays. Granular, in-furrow insecticides were once popular, but have been withdrawn from the market due to environmental concerns. 

    Because flea beetles emerge early in the spring and can migrate into seedling canola fields rapidly, insecticide-coated seed treatments are the most effective means of flea beetle control. [3],[13],[46]

    Since 2001, all seed treatments registered for control of flea beetles in Canada contain a neonicotinoid insecticide. This insecticide class has systemic activity in plants and inhibits nervous conduction in insects by blocking the nicotinoid acetylcholine receptor. [47]

    Coating seeds with an insecticide in combination with one or more fungicides prior to planting is a widespread practice. Essentially all of the canola grown in western Canada is treated with an insecticide seed treatment. [48] Seed treatments protect canola seedlings from flea beetles as soon as the plants emerge. Currently available neonicotinoid-based seed treatments may also have the option to include an additional group 28 (diamide) insecticide as part of the seed treatment package. Depending upon the rate selected, these particular enhanced seed treatment offerings can extend the period of protection from flea beetles, with some improvement in striped flea beetle control, and the addition of cutworm control with the group 28 insecticide especially under conditions that lead to slow crop emergence and development (e.g. early and/or direct seeding into cool soil temperatures). 

    In a greenhouse trial, when crucifer flea beetles were exposed to seedlings of canola grown from neonicotinoid-treated seed, they fed less and had higher mortality than striped flea beetles in the same trial. [51] The differential toxicity of seed treatments to the two species may result in a shift in their geographic distribution and economic importance. Also, for growers in regions where striped flea beetles are naturally more prevalent, the importance of frequent crop scouting to assess the need for foliar insecticide rescue treatments may be increased.

    If high flea beetle populations occur and the seed treatments are not protecting the seedlings adequately, use a foliar spray. Application of foliar insecticide may be required when feeding damage encompasses 25% of the leaf surface [49],[50]. If damage around field edges is high but flea beetles have not dispersed throughout the field, limiting insecticide application to the field perimeter may be sufficient to control the insect.

    Growers who routinely mix a foliar insecticide with their herbicides should check that flea beetle damage is actually at the threshold.  Spraying before damage reaches economic threshold can increase the risk of flea beetles developing resistance to insecticide, and has a negative impact on beneficial insects.

    Daily field scouting for flea beetles is important, particularly on hot, calm days. If plants are missing, determine if the cause is flea beetles, cutworms or seedling blight. A post-emergent insecticide application may be required to protect seedlings that are exposed to severe or prolonged periods of intense attack. If heavy flea beetle damage nears threshold levels and high numbers of flea beetles are noticed in the field, apply foliar sprays as soon as possible, since flea beetles can cause substantial damage quickly.

    Where damage starts at the field margins, it is possible that only a small portion of the field may require treatment. Apply sprays when it is sunny and warm, and the beetles are active and exposed on plants and soil. Additional foliar sprays may sometimes be needed since flea beetles may continue to move into fields at the susceptible stage after residual from the first foliar spray has become ineffective. Scout fields daily to determine if the insects have moved into the untreated areas and are damaging plants. 

    Insecticides registered for Flea Beetle control in canola.

    Source: Crop Protection 2020 (Alberta Agriculture and Forestry Edition)

    Group Number
    ApplicationLD50 (Mammalian
    Seed Treatments
    Helix Vibrance (contains Helix Xtra and Vibrance 500FS) Neonicotinoids 4A thiamethoxam Seed treatment Commercial Seed treatment 3129
    Visivio (contains Helix Vibrance and Rascendo - sulfloxaflor) Neonicotinoids 4A, 4C Thiamethoxam, sulfoxaflor Seed treatment Commercial Seed treatment 3129
    Gaucho CS FL / Gaucho 480 / Stress Shield 600 / Sombrero Neonicotinoids 4A imidacloprid Seed treatment Commercial Seed treatment > 300 - <2000
    Fortenza / Lumiderm Diamides 28 cyantraniliprole Seed treatment Commercial Seed treatment >5000
    Prosper Evergol / Poncho 600 FS / NipsIt Inside 600 Neonicotinoids 4A clothianidin Seed treatment Commercial Seed treatment >5000
    Foliar sprays
    Decis 5.0 EC / Poleci 2.5EC Pyrethroids 3A deltamethrin 7 Aerial or ground 395
    Mako / Up-Cyde / Ship 250 Pyrethroids 3A cypermethrin 30 Aerial or ground 542
    Matador; Silencer Pyrethroid 3A lambda-cyhalothrin 7 Aerial or ground 278
    Pounce; Ambush; Perm-UP Pyrethroid 3A permethrin Seedling application Aerial or ground 789-3000
    Sevin XLR Carbamates 1A Carbaryl Seedling application Aerial or ground 1375-2800
    Malathion Organo-phosphates 1B malathion 7 Aerial or ground 4302-5500
    Voliam Xpress Pyrethroid & Diamide 3A, 28 Lambda-cyhalothrin & chlorantraniliprole  7 Aerial or ground 98

    1 LD50 values represent the relative toxicity of a pesticide. They represent the dose (in mg/kg body weight) that will kill 50% of the test animals. Thus the lower the number the greater the toxicity. Values given are for oral female rat LD50.

    Note: Always read and follow current pesticide label directions.

    Crop Protection Guides

    Crop Protection 2019 (Alberta)

    Guide to Crop Protection – 2019 (Saskatchewan)

    Field Crop Protection 2019 (Manitoba)

    Steps to ensure the proper flea beetle spray decision

    Step 1. Recall the spray threshold. The action threshold for flea beetles in canola crops in Canada is an average leaf area loss of 25% or more. Yield loss starts to show after 25% leaf area loss and becomes economic (yield loss is more than the total cost of the foliar spray operation) at around 50% leaf area loss. The reason for the ‘action threshold’ for flea beetles is that leaf area loss can escalate quickly from 25% to 50% and beyond in a severe infestation.

    Step 2. Assess leaf area loss. With thresholds in mind, check plants in a number of areas of the field to get an average damage level, scouting the newest leaves (as these tend to be preferred). Flea beetle populations and damage tend to be in concentrated areas. If cotyledons are chewed up but newest leaves show very little feeding, then plants may be outgrowing the threat or seed treatments may be having an effect (or both). However, if cotyledons are showing under 50% damage but first true leaves are not present, flea beetles may be nipping off fresh apical meristem – the growing point for first leaves. If the meristem is lost, these leaves could be considered 100% lost. Mark those plants (could use the ‘washer’ test) and return in a day or two to see if true leaves are showing.

    Step 3. Assess stem damage. This is especially important in unfavourable weather (wind, cool) that drives flea beetles down to leaf undersides and stems. While feeding marks on the stem are likely much more consequential than feeding on a leaf, there isn’t  currently have a way to include stem feeding in the leaf-area loss thresholds. One shallow feeding mark (could be a few flea-beetle-sized bites) might not do any damage at all, but feeding that eats through the fragile new stem or causes it to break could be fatal. Plants that die due to stem feeding would have 100% leaf area loss – but seedlings that die in this fashion are hard to find and could also be lost for various other reasons, including cutworms, frost and seedling diseases. They are often missed when it comes to damage assessment. The key is to look for stem damage when scouting, particularly if conditions are, or have recently been, cool, moist or windy. If leaf area loss is below thresholds, but flea beetles are present in high numbers and the crop is not advancing, stem feeding may be the reason. Growers and agronomists observing this situation may want to be more aggressive with their spray decision, especially if the stand is thin (when losing more plants is of greater concern).

    Daily scouting needs to happen in areas approaching action threshold. Within two or three days, flea beetle feeding can escalate way beyond threshold, and actually wipe out whole areas of a field, especially in hot, dry and windy conditions.

    Step 4. Assess flea beetle feeding activity. Are the insects still present in the field and continuing to feed? If it looks like populations are dwindling, an application may not be necessary. If flea beetles are slow and lethargic, it may mean they have ingested seed treatment insecticide and are no longer feeding. If they don’t jump away from your hand, they are likely near the end of their life. Check again to make sure before making a decision. Time of day and weather can influence flea beetle activity. On rainy days, for example, flea beetles will usually take cover, so rain will slow or even stop feeding for the time being. Rain can also help the crop more quickly recover.

    Step 5. Consider the plant stand. This should influence your approach to the thresholds. With a thin stand of four plants per square foot, for example, growers can’t afford to lose any plants and may want to take action quickly as damage approaches 25%. But with counts in the high end of the recommend range (of 5 to 8 plants per square foot), growers can afford to lose a couple of plants without sacrificing harvest yield.

    Step 6. Check the crop stage. After the 4-leaf stage (four true leaves), the threat is likely over because the crop usually has enough plant material to feed flea beetles without compromising growth, and the plants can compensate for feeding better by this stage. If the crop is uneven (some plants are at the 4-leaf stage and some are earlier), keep scouting until most of the crop has at least three or four true leaves.

    Step 7. Check canola fields frequently. Seed treatment insecticide starts working when the seed imbibes water and it can remain active for about 3-4 weeks after that point. If you have enough moisture for seed to imbibe and germinate, you have enough to solubilize the active ingredient and allow it to move into the plant. Flea beetles need to consume some plant tissue to get a dose of the protectant. High levels of flea beetles can overwhelm seed treatments. In a slow developing crop, seed treatments can lose their protective capacities before the crop reaches the 4-leaf stage. Scout often during these first three weeks, and if flea beetle levels are building and are close to thresholds, daily checking for a few days may be required.

    Step 8. If spraying is required, only use pesticides registered for flea beetles in canola. Refer to product labels for proper use instructions. No pre-harvest interval concerns exist at this stage, but this could be a deciding factor on which product to use later in the season: Specific products are limited to one application per season and a grower may want to keep these in reserve. See Insecticide control options for further detail.



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    Date modified: June 10, 2019