Summary Of Insects On Crops In Manitoba In 2010

10 November, 2010

Compiled by: Field Crops, John Gavloski, Entomologist, Manitoba Agriculture, Food and Rural Initiatives, Crops Knowledge Centre, Phone: 204-745-5668; Fax: 204-745-5690. 

 Horticultural and Forage Crops, Brent Elliott, Entomologist, Manitoba Agriculture, Food and Rural Initiatives,Crops Knowledge Centre, Phone: 204-745-5669; Fax: 204-745-5690.

Abbreviations used: The following abbreviations will be used in this document to indicate the following agricultural regions in Manitoba; NW=Northwest, SW=Southwest, C=Central, E=Eastern, I=Interlake.

Estimated acres: Unless otherwise indicated, estimated acres grown in Manitoba in 2010 (shown in brackets under each commodity title) are from the Manitoba Crop Insurance Corporations 2010 Variety Market Share Report. The symbol ↑ indicates an increase in acres from 2009, whereas ↓ indicates a decrease in acres from 2009.


There were few insect problems in cereal crops in 2010. Armyworms were a concern in some fields. Shipments of larvae of cereal leaf beetle containing the parasitoid Tetrastichus julis (Eulophidae) were released in some fields near Swan River.  In canola, cutworms were a problem in some fields. Root maggots and damage to plants was noticed in some fields that were in canola for the second year in a row. Diamondback moth were a concern in the Eastern and Central regions of Manitoba. Lygus bugs were the main insect concern in sunflower fields. Green cloverworm were a concern in soybeans and dry edible beans.

Small Grain Cereals

(Wheat (spring)-2,579,940 acres↓ + 3,004 acres organic↓; Wheat (Winter)-218,125↓ + 952 acres organic↑; Barley-436,004 acres↓; Oats-498,622 acres↑ + 4,675 acres organic↑; Fall Rye-49,776 acres↓; Triticale-636 acres↓)

Wireworms: Some higher levels of wireworms and damaged areas were reported from a wheat field in the Teulon (I) area.

Cutworms: Cutworm control was applied in an oat field south of MacGregor (C).

Aphids: A field of spring wheat near Onanole (SW) was treated with insecticide to control aphids; up to 30 aphids per head were present in areas of the field. Aphids were also reported on cereals in the St. Pierre (E) area. Overall, aphid numbers were low on cereals in Manitoba.

Thrips: In contrast to 2009, no economical issues with thrips on cereals were reported in 2010. Some thrips feeding was noted on winter wheat near Sanford (C).

Wheat midge (Sitodiplosis mosellana): Egg Laying by wheat midge appeared to start in the second week of July. There were no reports of high levels of wheat midge.

Grasshoppers: No grasshopper problems in small grains were reported in 2010.

Cereal Leaf Beetle (Oulema melanopus): Cereal leaf beetle was found in some cereal fields in the Swan River Valley (NW). About 20 acres of spring wheat south of Minitonas was sprayed for cereal leaf beetle. Feeding was also noticeable on some spring wheat near Swan River.

Shipments of larvae of cereal leaf beetle containing the parasitoid Tetrastichus julis (Eulophidae) were sent from Lethbridge, Alberta to Swan River and released in fields near Swan River. On July 21st, a total of about 350 parasitized larvae were released in 2 fields of spring wheat near Swan River and 1 field of spring wheat near Minitonas. A second release of about 245 parasitized larvae was done in mid-August.

Armyworm (Mythimna [formerly Pseudaletia] unipuncta): Armyworm larvae began to be noticed in late June. Some wheat in the Winkler (C) area was sprayed with insecticide to control armyworms.

Wheat Curl Mites (Aceria tosichella): Wheat streak mosaic was common in southern Manitoba this year. Some fields were reseeded to other crops as a result.

Slugs: In mid-July, about 30 acres of wheat in the Northwest was being heavily fed on by slugs. There were high levels of tissue striped from some of the flag leaves.


(171,816 acres grain corn↑; 46,613 acres silage corn↓; 539 acres open pollinated↓)

Cutworms: Cutworms were controlled, with insecticides, in some corn fields near Carman in late May. Both redbacked (Euxoa ochrogaster) and dingy (Feltia jaculifera) cutworms were found while scouting in one of these fields.

European corn borer (Ostrinia nubilalis): In 2010, 54.9 % of grain corn was seeded to Bt varieties, and 17.7% of silage corn was seeded to Bt varieties. There were no reports of economical levels of European corn borer in grain or silage corn in Manitoba in 2010. European corn borer were hard to find during fall sampling of fields of corn with varieties susceptible to European corn borer.

Western Bean Cutworm (Striacosta albicosta): Western bean cutworm has never been detected in Manitoba, but has been confirmed in Minnesota and North Dakota, both of which border Manitoba. Pheromone-baited unitraps were set up at six locations from July 5 to August 20 to monitor for the presence of moths of western bean cutworm in Manitoba. No western bean cutworms were found in any of the traps. A lot of redbacked cutworm (Euxoa ochrogaster) moths were collected from 2 of the traps near Altona (C). Some of the markings on the wings are similar in these species, so samples were sent to the Eastern Cereal and Oilseed Research Centre in Ottawa, where it was confirmed these were redbacked cutworm adults and not western bean cutworm. Moths of six other species of Noctuidae were also found in these traps.

Canola And Mustard

(Argentine canola-3,292,707 acres↑; Polish canola-1,223 acres↓; Mustard-5,359 acres↓)

Flea beetles (Phyllotreta spp.): Use of seed treatments containing neonicotinoid insecticides to manage early-season flea beetle populations continues to be common. There was some spraying to control flea beetles in the Swan River (NW) area as well.

Cutworms: Cutworms populations were high and at times economical in canola fields in the central, northwest and southwest regions of Manitoba. Reports of concerns over high levels of cutworm damage were received from May18th to June 22nd. Insecticides were applied to control cutworms in some canola field. Spraying for cutworms in canola is known to have occurred in fields near Dauphin (NW), Swan River (NW), Minto (SW), and Wellwood (SW).

Root Maggots (Delia spp.): Root maggots and damage to plants were noticed in some fields in the Central region that were in canola for the second year in a row. In one of these fields, plants were reported to be falling over, with some roots pinched off.

Bertha Armyworm (Mamestra configurata): Pheromone-baited traps to monitor adult moths of bertha armyworm were set up at 80 locations in Manitoba in 2010. The monitoring period was June 7th to August 1st. Cumulative moth counts suggested populations were at low risk of being problematic in most regions of Manitoba in 2010. Table 1 shows the highest trap counts for 2010.

Table 1. Highest cumulative counts of bertha armyworm (Mamestra configurata) in pheromone-baited traps in Manitoba in 2010.

Nearest Town Region Trap Count Risk Category
Benito Northwest 730 Uncertain
Pilot Mound Central 294 Low
Carberry Southwest 219 Low
Neepawa Southwest 165 Low

Peak trap catches occurred in most traps during the weeks of June 28-July 4th and July 5-11th. The highest trap catch in a single week was 400 at the trap near Benito on the week of July 5-11th.

There were no reports of high levels of larvae of bertha armyworm or insecticides being applied to control bertha armyworm in Manitoba in 2010.

Diamondback moth (Plutella xylostella): Pheromone-baited traps for adult moths were set up at 84 locations in Manitoba in 2010. The monitoring period was generally from May 10th to June 20th. Table 2 summarizes the results. Table2. Dates of first detection of diamondback moth (Plutella xylostella) in pheromone-baited traps in Manitoba in 2010.

Region Week of first diamondback moth in traps Week when trap(s) from region first reports cumulative count of >10 Week when trap(s) from region first reports cumulative count of >100 Highest cumulative count from region and location
Eastern May 10-16 May 10-16 May 24-30 393 Landmark 9 traps>100
Interlake May 10-16 May 31-June 6   36 Moosehorn
Central May 10-16 May 10-16 May 31- June 6 243 Morris
Southwest May 10-16 May 31-June 6   82 Griswold
Northwest May 17-23 May 17-23   56 Minitonas

The highest single week count was 137 near Dugald (E) during the week of May 31- June 6. Highest trap catches were in the eastern part of Manitoba.

There were some insecticide applications for diamondback moth in canola in 2010. Canola fields near Winkler (C), Morris (C), and Altona (C) are known to have been sprayed to control diamondback moth.

Lygus bugs (Lygus spp.): Levels of lygus bugs in canola were generally low, and there were no reports of populations near or at economic threshold.

Cankerworms: Although highly localized and not an economical threat, an interesting situation was observed where cankerworms were feeding on canola near a shelterbelt in a field south of Winkler (C). Debris from the shelterbelt had blown onto the field from previous strong winds.


(Flax-161,572 acres↓ + 2,012 acres organic flax↓)

Potato aphid (Macrosiphum euphorbiae): There were some reports of aphids at threshold levels in flax in late-July / early-August. High levels of beneficial insects was also noted.


(122,378 acres non-oil↑; 15,407 acres oil↓)

Wireworms: There were no reports of wireworm damage to sunflowers in Manitoba in 2010. Some sunflower fields were seeded with Cruiser (thiamethoxam) seed treatment.

Cutworms: A couple of sunflower fields in the MacGregor (C) area were treated with insecticide in mid-May to control cutworms.

Sunflower beetle (Zygogramma exclamationis): No high population or spraying for sunflower beetles was reported in 2010.

Grasshoppers: Some field margins were sprayed in early-July to prevent grasshopper encroachment into fields. Otherwise no grasshopper problems in sunflowers were reported.

Seedhead Insects

Many fields of confection sunflowers were again treated with insecticides during early flowering to control seedhead insects. Lygus bugs (Lygus spp.) were the main pest species present in many of these fields. Populations of Red sunflower seed weevil (Smicronyx fulvus) were very low again this year, and usually hard to find when scouting for insects on sunflower heads. Banded Sunflower Moth (Cochylis hospes) were present but there were no reports of high levels of larvae.

The plant bug Chlamydatus associatus was found in some sunflower fields as well. What it is feeding on and whether it can cause damage to sunflowers is not known.

Monitoring of Lepidoptera: Pheromone-baited traps for banded sunflower moth were placed in sunflower fields at 6 locations from July 12 to August 27th as part of a program to monitor the emergence and relative abundance of banded sunflower moths in sunflower growing areas of Canada and the U.S.

Table 3. Cumulative counts from pheromone-baited traps for banded sunflower moth (Cochylis hospes) in Manitoba in 2010.

Trap Location and Region Cumulative Count (July 12 - August 27)
Gretna                     Central 615
Morden                   Central 621
Rathwell                  Central 552
Rosser                    Interlake 749
Souris                     Southwest 1,281
Waskada               Southwest 1,294

Pheromone baited traps were also used to monitor for Cochylis arthuri and the sunflower moth (Homoeosoma electellum).

Beans (Dry Edible)

(145,825 acres↑: White pea (navy)-51,659 acres↑, pinto-52,724 acres↓, black-20,049 acres↑, kidney-10,356 acres↓, cranberry-3,732 acres↑, small red-1,655 acres↓, other dry ebible-5,650 acres)

Seedcorn maggot (Delia platura): Plant injury from seedcorn maggots was noticeable in a field of navy beans in the Central region. Some plants where the maggots were found were wilted.

Green Cloverworm (Hypena scabra): Green cloverworm was noticeable in many fields of dry beans. Some pod feeding was reported, and high levels of defoliation were reported from fields in the Altona (C) and Winkler (C) area.

Peas (Field)

(89,587 acres↑)


Pea aphids (Acyrthosiphon pisum): There were some pea fields in the Southwest and Central regions that had aphid levels above economic threshold in mid-July.


(528,127 acres↑)

Cutworms: A field of soybeans near Dugald (E) had a high level of damage from cutworms, and was sprayed to control the cutworms. Some more minor cutworm damage to soybeans was reported from the Landmark-Niverville (E) area.

Soybean Aphid (Aphis glycines): The first report of soybean aphids in Manitoba in 2010 was on July 19th. Although populations did increase through late-July and August, there were no reports of populations reaching economic levels. Populations as high as 100/plant were reported from the Beausejour (E) area, and a couple of soybean fields with aphid levels close to threshold were reported from the Teulon (I) area.

Green Cloverworm (Hypena scabra): Green cloverworm were present in many soybean fields. Although the first report of their presence in soybeans was on June 28th, most of the higher levels of defoliation was noted in late-August and early-September. There was some spraying in fields near Carman (C) and Homewood (C).


(4,577 acres↓)

No insect concerns were reported from fababeans in Manitoba in 2010.


(10,063 acres↑)

Aphids: Aphid levels as high as 30-50 per sweep were reported on some lentils in the southwest. Heavy thunderstorms are suspected as helping to regulate aphid levels. There were no reports of insecticide use in lentils.


(19,755 acres↑)

Aphids: Some low levels of aphids were reported from canary seed in southwestern Manitoba. Other than this there were no reports or concerns over insects in canary seed.


(9,187 acres for grain↑)

No economical insect concerns were reported from hemp in 2010.

Forages And Forage Seed

Alfalfa Weevil (Hypera postica): Problems due to alfalfa weevil appear to be declining. Some damage from alfalfa weevil to alfalfa in some mixed forage strands near Ste. Rose (NW) was reported in late-June. Some insecticides were applied to alfalfa seed crops in the Interlake to control alfalfa weevil and other insects prior to leafcutter bees being placed in the fields. Concerns over alfalfa weevil in seed alfalfa near Dauphin (NW) were also reported in mid-June.

Armyworm (Mythimna [formerly Pseudaletia] unipuncta): A field of ryegrass east of Altona (C) was sprayed with insecticide to control armyworms. It’s was reported that populations of 20-30/m2 were being found.


Data on estimated acres in Manitoba from Statistics Canada (July 16, 2010): 70,000 acres↓

Colorado potato beetle (Leptinotarsa decimlineata): Numbers were extremely low in Manitoba; so low that populations of adults were insufficient for resistance testing purposes. No anecdotal indications of resistance have been reported as yet.

Aphids: Aphid numbers were low in general, though green peach aphids could be considered moderate.

Wireworms: Reports of wireworm damage seem to be on the increase.

Potato leafhopper (Empoasca fabae): Potato leafhopper numbers were very low.

Potato flea beetle (Epitrix cucumeris): Potato flea beetle numbers were very low

Carrots, Cole Crops, And Other Vegetable Crops

Carrots: Aster leafhopper (Macrosteles quadrilineatus): Numbers returned to normal after two consecutive years of low population. Populations were sufficiently high to require control measures several times through the growing season. Estimates of percent of crop negatively impacted would be about 20% (normal).

Brassicas: Lepidopterous pests were moderate this year. Diamondback moth numbers were low to moderate; cabbage looper (Trichoplusia ni) numbers were higher than normal thanks to a reasonable migratory population; imported cabbageworm (Pieris rapae) numbers are on the increase and caused significant damage in some cabbage fields.

Sweet Corn: Most fields were sprayed on a calendar basis for management of European corn borer. Fourspotted sap beetles (Glischrochilus quadrisignatus) were an issue for some areas (Portage la Prairie south to Winkler).

Berry Crops

Raspberry: Populations of fourspotted sap beetles were significant this year and most raspberry plots required treatment.

Strawberry: Tarnished plant bug (Lygus lineolaris) numbers returned to normal this year and routine sprays were applied prior to peak flowering.