Weekly Update (June 27, 2019; Wk 12) Otani, Weiss, Giffen, Trudel, Turkington, Svendsen, Olfert, Vankosky

Greetings!

Another busy week of in-field monitoring, data collection, and field tour events for all our Staff!  A reminder that, from now until mid-July, the Weekly Update may need to be posted in multiple segments (i.e., at any point from Wednesday-Saturday).  Please bookmark the Blog or subscribe to receive the latest growing season information!

This week, special thanks to Ross Weiss (AAFC-Saskatoon) - entomologist and the integral modeler who works to generate all the weekly wind trajectory, meteorological, and predictive model updates supporting the Prairie Pest Monitoring Network. 

Please access the complete Weekly Update either as a series of Posts for Week 12 (June 27, 2019) OR a downloadable PDF. Be sure to check out the Insect of the Week - the rest of the growing season features doppelgangers to aid in-field scouting!

Questions or problems accessing the contents of this Weekly Update?  Please e-mail either Dr. Meghan Vankosky or Jennifer Otani.  Past “Weekly Updates” can be accessed on our Weekly Update page.

Subscribe to the Blog by following these easy steps!

Weather synopsis (June 27, 2019; Wk 12)

Weather synopsis – Temperatures this week, June 18-24, 2019, were similar to last week. Over the past seven days temperatures were cooler than normal. The warmest temperatures were observed across MB while temperatures were cooler in western SK and across AB (Fig. 1). The is a complete reversal to last week.  

Figure 1. Average temperature (°C) across the Canadian prairies the past seven days (June 16-24 2019).

Average 30 day temperatures were warmest across southern MB and SK (Fig. 2). Cooler temperatures were reported across eastern and northern AB. The mean temperature differences from normal (May 21 – June 17, 2019) have been zero to two °C warmer than normal for AB and SK while temperatures in MB have been zero to two °C cooler than normal (Fig. 3). 

Figure 2. Average temperature (°C) across the Canadian prairies the past 30 days (May 26-June 24 2019).

Figure 3. Mean temperature difference from Normal across the Canadian prairies over the past 30 days (to June 17, 2019).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Growing season temperatures (April 1-June 24, 2019) have been warmest across the southern prairies (Fig. 4). The warmest growing season temperatures have been reported for southern AB and an area south of Winnipeg MB. Across the prairies, the average growing season temperature has been 1.2 °C below normal.

Figure 4. Average temperature (°C) across the Canadian prairies for the growing season (April 1-June 24 2019).

This past week significant rainfall amounts were reported for most of SK and across central  regions of AB (Fig. 5). Across the prairies, rainfall amounts for the past 30 days (May 26 – June 24, 2019) have been near normal (Fig. 6). The Edmonton region has been the wettest. 

Figure 5. Cumulative precipitation observed the past seven days across the Canadian prairies (June 18-24 2019).

Figure 6. Cumulative precipitation observed the past 30 days across the Canadian prairies (May 26-June 24, 2019).

Growing season rainfall (April 1 – June 24) amounts have been below average for most of the prairies, particularly across southern regions of AB (Fig. 7). Based on modeled soil moisture (Fig. 8), recent rains have improved soil moisture values across a large area of SK. Predicted soil moisture continues to be low across large regions of eastern MB and southern AB. 

Figure 7. Cumulative precipitation observed for the growing season (April 1-June 24, 2019) across the Canadian prairies.

Figure 8. Modeled soil moisture (%) across the Canadian prairies as of June 24, 2019.

The growing degree day map (GDD) (Base 5 ºC, April 1-June 24, 2019) is below (Fig. 9):

Figure 9. Growing degree day (Base 5 ºC) across the Canadian prairies for the growing season (April 1-June 24 2019).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The growing degree day map (GDD) (Base 10 ºC, April 1-June 24, 2019) is below (Fig. 10):

Figure 10. Growing degree day (Base 10 ºC) across the Canadian prairies for the growing season (April 1-June 24, 2019).Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The lowest temperatures (°C) observed the past seven days ranged from about 11 to 0 °C in the map below (Fig. 11).

Figure 11. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (to June 24, 2019).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (25Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The highest temperatures (°C) observed the past seven days ranged from about 16 to at least 27 °C in the map below (Fig. 12).

Figure 12. Highest temperatures (°C) observed across the Canadian prairies the past seven days (to June 24, 2019).

Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (24Jun2019).  Access the full map at http://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

The maps above are all produced by Agriculture and Agri-Food Canada.  Growers can bookmark the AAFC Drought Watch Maps for the growing season.

Wind Trajectories (June 24, 2019; Wk 12) Weiss, Trudel, Giffen, Vankosky

Agriculture and Agri-Food Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990's.

In a continuing effort to produce timely information, the wind trajectory reports are available in two forms:

• DAILY REPORTS, as they can be generated, are accessible as a downloadable PDF file on this page.
• WEEKLY REPORTS can be retrieved by clicking this hyperlink with the most recent version available here.

Predicted grasshopper development (June 27, 2019; Wk 12)

Grasshopper Simulation Model Output – The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).

Across the prairies the grasshopper hatch is well underway with most locations having approximately 27% of the population in the egg stage. Based on model runs, approximately 33% (30% last week) of the population is in the first instar, 26% (14.5% last week) is predicted to be in the second instar, and 11% (4.3% last week) in the third instar and just over 1% are predicted to be in the fourth instar.   The following map indicates that grasshopper populations across the southern prairie are mostly in the second instar.

Figure 1. Predicted development stages of grasshopper (Melanoplus sanguinipes) populations across

the Canadian prairies (as of June 24, 2019). 

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture, Saskatchewan Agriculture, Alberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide" which is available as a free downloadable document in either an English-enhanced or French-enhanced version.

Predicted bertha armyworm development (June 27, 2019; Wk 12)

Bertha armyworm (Lepidoptera: Mamestra configurata) - Bertha armyworm adults should be emerging across the prairies and oviposition is predicted to have begun across most of the southern prairie regions of SK, AB and MB (Fig. 1).

Figure 1.  Predicted precent of bertha armyworm (Mamestra configurata)  populations at EGG STAGE across the Canadian prairies as of June 24 2019. 

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of Manitoba, Saskatchewan, Alberta and the Prairie Pest Monitoring Network. Also refer to the bertha armyworm pages within the "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide" which is a free downloadable document as both an English-enhanced or French-enhanced version.

Again, thanks to John Gavloski (Manitoba Agriculture) who helped update the PPMN Bertha armyworm monitoring protocol.  Use the images below (Fig. 2) to help identify moths from the by-catch that will be retained in phermone-baited unitraps.

Figure 2. Stages of bertha armyworm from egg (A), larva (B), pupa (C) to adult (D).
Photos: J. Williams (Agriculture and Agri-Food Canada)

Also be sure to review the Insect of the Week which features bertha armyworm and its doppelganger, the clover cutworm!

Wheat midge (June 27, 2019; Wk 12)

Wheat Midge (Sitodiplosis mosellana) –  Wheat midge and its doppelganger, the lauxanid fly, were featured as the Insect of the Week (for Wk10).  Check that post for help with in-field scouting for this economic pest of wheat!  The differences between midges and parasitoid wasps are featured as the current Insect of the Week (for Wk11).  Not all flying insects are mosquitoes nor are they pests - many are important parasitoid wasps that actually regulate insect pest species in our field crops.

Wheat midge adults generally emerge during the first week of July. Compared to long term normal values for temperature and rainfall, May and June in the Saskatoon region has been approximately 1 °C cooler and rainfall is 40-60% less than normal. Dry conditions in May and June can have significant impact on wheat midge emergence. Insufficient rainfall in May and June can result in delayed movement of larvae to the soil surface. Elliott et al (2009) reported that wheat midge emergence was delayed or erratic  if rainfall did not exceed  20-30 mm  during May. Olfert et al. 2016 ran model simulations to demonstrate how rainfall impacts wheat midge population density. Our wheat midge model indicates that dry conditions may result in:
   a. Delayed adult emergence and oviposition 
   b. Reduced numbers of adults and eggs

The wheat midge model indicates that 70% (82% last week) of the population are in the larval  cocoon stage and 29% (18% last week) of the population is predicted to have moved to the soil surface. The first map presents wheat midge development as of last week (Fig. 1). 

Figure 1.  Percent of larval population at the soil surface (as of June 17, 2019) across the Canadian prairies.

Results indicate that dry conditions delayed development of larval cocoons in SK. Adequate precipitation in AB and MB should have resulted in movement of larvae to the soil surface.  The model indicates that recent rain has resulted in larval development (larval cocoons) across SK. The second map indicates that recent rain in SK should result in development of larval cocoons and subsequent movement of larvae to the soil surface (Fig. 2). The third map (Fig. 3) indicates that pupae may be present in some fields in southern AB and MB. It should be noted that, based on fall surveys in 2018, wheat midge populations were expected to be low across most of AB and SK.

Figure 2. Percent of larval population at the soil surface (as of June 24, 2019) across the Canadian prairies.

Figure 3.  Percent of  population AT PUPAL STAGE (as of June 24, 2019) across the Canadian prairies.

Monitoring:
When monitoring wheat fields, pay attention to the synchrony between flying midge and anthesis.  

In-field monitoring for wheat midge should be carried out in the evening (preferably after 8:30 pm or later) when the female midges are most active. On warm (at least 15ºC), calm evenings, the midge can be observed in the field, laying their eggs on the wheat heads (photographed by AAFC-Beav-S. Dufton & A. Jorgensen below). Midge populations can be estimated by counting the number of adults present on 4 or 5 wheat heads. Inspect the field daily in at least 3 or 4 locations during the evening.

REMEMBER that in-field counts of wheat midge per head remain the basis of economic threshold decision.  Also remember that the parasitoid, Macroglenes penetrans (photographed by AAFC-Beav-S. Dufton below), is actively searching for wheat midge at the same time.  Preserve this parasitoid whenever possible and remember your insecticide control options for wheat midge also kill these beneficial insects which help reduce midge populations.

Economic Thresholds for Wheat Midge:
a) To maintain optimum grade: 1 adult midge per 8 to 10 wheat heads during the susceptible stage.
b) For yield only: 1 adult midge per 4 to 5 heads. At this level of infestation, wheat yields will be reduced by approximately 15% if the midge is not controlled.

Inspect the developing kernels for the presence of larvae and the larval damage. 

Information related to wheat midge biology and monitoring can be accessed by linking to your provincial fact sheet (Saskatchewan Agriculture or Alberta Agriculture & Forestry).  A review of wheat midge on the Canadian prairies was published by Elliott, Olfert, and Hartley in 2011.  

NEW - Alberta Agriculture and Forestry has also released a YouTube video describing in-field monitoring for wheat midge this week.  

More information about Wheat midge can be found by accessing the pages from the new "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Field Guide".  View ONLY the Wheat midge pages but remember the guide is available as a free downloadable document as both an English-enhanced or French-enhanced version.

Cereal Aphid Manager (CAM) (June 27, 2019; Wk12)

Reminder  and Congratulations!  The Cereal Aphid Management (CAM) Mobile Application Team was recognized with an Agriculture and Agri-Food Canada Gold Harvest Award this month!  Team members included Ashraf Eid, Paul Faure, John Gavloski, François Jodoin, Elham Karimi, Eric Li, Jackson Macdonald, Nancy MacDonald, Owen Olfert, Chrystel Y. Olivier, 

Daniel Shen, Erl Svendsen, Gabriel Tobian, Tyler J. Wist.

"The app is a culmination of innovative thinking, extensive research, and most importantly collaboration in order to design a tool that met the needs of the farming community. The team’s ability to work together and build this application will result in economic savings, a greener environment, and increased crop quality in the food production industry."

The Cereal Aphid Manager is an easy-to-use mobile app that helps farmers and crop advisors control aphid populations in wheat, barley, oat or rye. It is based on Dr. Tyler Wist's (AAFC-Saskatoon) innovative Dynamic Action Threshold model. The model treats the grain field as an ecosystem and takes into account many complex biological interactions including:

• the number of aphids observed and how quickly they reproduce
• the number of different natural enemies of aphids in the field and how many aphids they eat or parasitize per day
• the lifecycles of aphids and their enemies taking into account developmental stages, egg laying behaviour, population growth rate, lifespan, etc.

By taking into consideration factors like these, the app predicts what the aphid population will be in seven days and the best time to apply insecticide based on economic thresholds.

Available in iOS and Android.

To learn more and to download, go to AAFC's CAM webpage.

Note: Cereal aphids can blow up from the South at any time which cannot be predicted by the app. Therefore, farmers and crop advisors should regularly check fields during the growing season regardless of what Cereal Aphid Manager Mobile may recommend.

CAM Homepage

CAM monitoring report and recommendation

CAM icon

Provincial Insect Pest Reports (June 27, 2019; Wk 12)

Provincial entomologists provide insect pest updates throughout the growing season so we link to their most recent information: 

• Manitoba's Insect and Disease Updates for 2019 are posted here. Access Update #4 posted June 12, 2019.

• Saskatchewan's Crops Blog Posts includes a segment on "Early season scouting of cutworms" by Sara Doerksen posted in April 2019 and "Economic thresholds" by Kaeley Kindrachuk posted in May 2019. Also access the Crop Production News with Issues #1 (featuring Diamondback moth monitoring), #2 (featuring Pest surveying and Pea leaf weevil in peas and faba beans), and #3 (featuring Bertha armyworm and Pea leaf weevil information).

•  Alberta Agriculture and Forestry's Call of the Land regularly includes insect pest updates from Mr. Scott Meers. The most recent Call of the Land was posted March 18-22, 2019 but did not include an insect update. In the meantime, try Agri-News to access the June 10, 2019 edition including information pertaining to the value of in-field monitoring.

Crop reports (June 27, 2019; Wk 12)

Crop reports are produced by:
• Manitoba Agriculture (June 18, 2019 or access the current online report)
• Saskatchewan Agriculture (June 11-17, 2019) or access the current online report).
• Alberta Agriculture and Forestry Crop Report (June 18, 2019 or access the current online report)

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (read the June 24, 2019 edition).

• The USDA's Weekly Weather and Crop Bulletin (read the June 16-22, 2019 edition). 

Field Events - Speak to an entomologist (June 27, 2019; Wk 12)

Public summer field events - Coming to a field near you –  Prairie field crop entomologists are already scheduled to be at these 2019 field tour events from May-August (be sure to re-confirm dates and details as events are finalized):

•  June 26, 2019: 2019 CanolaPALOOZA to be held at the Lacombe Research and Development Centre (Lacombe AB).  View event info/registration details.  Entomologists tentatively participating: Jennifer Otani, Amanda Jorgensen, Meghan Vankosky, Scott Meers, Patty Reid, Sunil Shivananjappa, Hector Carcamo, Julie Soroka, Mark Cutts, Jim Tansey, Sherrie Benson and the Junior Entomologists.

•  July 9-12, July 16-18, 2019: Crop Diagnostic School. Held at the University of Manitoba Research Farm at Carman, Manitoba. An 2-week diagnostic school will complete units on entomology, plant pathology, weed science, soil fertility, pulse crop production, and oilseed production. View registration and event information. Entomologists participating: John Gavloski and Jordan Bannerman.

•  July 9, 2019: CanolaPALOOZA Saskatoon, to be held at the SRDC Llewellyn Farm. Read more about this event.  Entomologists presenting: Tyler Wist, James Tansey, Greg Sekulic, Meghan Vankosky

•  July 22, 2019: Pulse grower gathering held near Three Hills AB.  Check Alberta Pulse Growers Event Page for more information.  Entomologists presenting: Graduate students from Dr. Maya Evenden's (U of A) working on pea leaf weevil.

•  July 23-24, 2019: Crop Diagnostic School, Scott Saskatchewan. Read more about this event.  Entomologists presenting: Meghan Vankosky, Tyler Wist.

•  July 24, 2019: Crops-a-Palooza. Held at Canada-Manitoba Crop Diversification Centre (CMCDC), Carberry, Manitoba. Read more about this event. Entomologist participating: John Gavloski, Vincent Hervet, Tharshi Nagalingam, Bryan Cassone.

•  August 8, 2019:  2019 Wheatstalk to be held at Teepee Creek AB.  View event info/registration details.   Entomologists tentatively participating: Jennifer Otani, Amanda Jorgensen, Boyd Mori.

•  August 8, 2019. Horticulture School. Agriculture and Agri-Food Canada Research Farm, Portage la Prairie, Manitoba. View event info/registration details.  Entomologist presenting: John Gavloski, Kyle Bobiwash.

Prairie Crop Disease Monitoring Network (June 24, 2019; Wk 12) - Turkington

The Prairie Crop Disease Monitoring Network (PCDMN) represents the combined effort of our prairie pathologists who work together to support in-field disease management in field crops.  

In 2019, the PCDMN will release a series of weekly Cereal Rust Risk Reports throughout May and June.  Information related to trajectory events based on forecast and diagnostic wind fields and cereal rust risk is experimental, and is OFFERED TO THE PUBLIC FOR INFORMATIONAL PURPOSES ONLY. 

Background:  Agriculture and AgriFood Canada (AAFC) and Environment and Climate Change Canada (ECCC) have been working together to study the potential of trajectories for monitoring insect movements since the late 1990s. Trajectory models are used to deliver an early-warning system for the origin and destination of migratory invasive species, such as diamondback moth. In addition, plant pathologists have shown that trajectories can assist with the prediction of plant disease infestations and are also beginning to utilize these same data. An introduction will be presented of efforts to identify wind trajectory events that may bring rust urediniospores into Western Canada from epidemic areas in the central and Pacific northwest (PNW) regions of the USA. Identification of potential events as well as an assessment of epidemic severity from source locations, and prairie weather conditions, will be used to assess the need for prompt targeted crop scouting for at-risk regions of the Canadian Prairies.

Two documents are available from the PCDMN:
•  An introduction to cereal rust risk and wind trajectories from the USA.
• WIND TRAJECTORY AND CEREAL RUST RISK REPORT for June 24, 2019

Summary of wind trajectory and cereal rust risk assessment and the need for in-crop scouting in the Prairie region, June 18-24, 2019:

1. Pacific Northwest – Currently there is limited stripe rust development in the PNW, although there has been a moderate number of recent wind trajectories from the PNW.  Rainfall did occur in SK and some regions of Alberta.  Winter wheat is progressing into heading and beyond, and spring wheat is moving from the stem elongation stage to flag leaf emergence.  Thus, as of June 24, 2019, the risk of stripe rust appearance from the PNW is relatively low and scouting for this disease is not urgent.  

2. Texas-Oklahoma corridor – In general, crops are advancing towards maturity, while in many areas of Texas and Oklahoma crops have been harvested or are being harvested, and thus winter wheat crops in these areas are less of a source of rust inoculum.  There were no recent wind trajectories from this area, while rainfall did occur in SK and some regions of Alberta.  Winter wheat is progressing into heading and beyond, and spring wheat is moving from the stem elongation stage to flag leaf emergence.  Thus, as of June 24, 2019, the risk of leaf and stripe rust appearance from the Texas-Oklahoma corridor is low and scouting for these diseases is not urgent.  

3. Kansas-Nebraska corridor – Kansas crops are starting to mature with harvesting starting in some regions. In Nebraska, leaf and stripe rust development continues, and thus over the next few weeks this region could act as a significant source of rust inoculum for the Prairie region.  From June 18-24, 2019 there has been a low-moderate number of wind trajectories from this area.  Rainfall did occur in SK and some regions of Alberta, while winter wheat is progressing into heading and beyond, and spring wheat is moving from the stem elongation stage to flag leaf emergence.  Thus, as of June 24, 2019, the risk of leaf and stripe rust appearance from the Kansas-Nebraska corridor is relatively low and scouting for these diseases is not urgent.  Although further development of rust in Nebraska may increase the risk, the crop will soon start to progress towards maturity and will become less of a source of the cereal rusts.  It should be noted that rust symptoms have been observed in research plots in St. Paul, MN (Cereal Rust Survey, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, Dr. O. Fajolu, USDA-ARS Cereal Disease Lab, June 18, 2019).  Stripe and leaf rust have also been observed in research plots at the South Dakota State University Research Farm, while no rust was observed in commercial fields in southeastern and southcentral regions of the SD (Cereal Rust Survey, CEREAL-RUST-SURVEY@LISTS.UMN.EDU, Dr. E. Byamukama, South Dakota State University, June 18, 2019).

4. Currently, we are not aware of reports of stripe or leaf rust in commercial fields of winter or spring wheat across the Prairie region.

5.  Access the full downloadable report.

Previous Posts (June 27, 2019; Wk 12)

Click to review these earlier 2019 Posts:

2019 Risk and forecast maps - Week 2

Alfalfa weevil - Week 11

Bertha armyworm - Week 11

Cabbage seedpod weevil - Week 11
Cereal aphid APP - Week 10
Cereal leaf beetle - Week 9
Crop protection guides - Week 6
Cutworms - Week 5

Field heroes - Week 6
Flea beetles - Week 5

Grasshoppers - Week 10

Insect scouting chart for Canola - Week 5
Insect scouting chart for Flax - Week 5

Monarch migration - Week 11

Painted lady butterfly - Week 8
Pea leaf weevil - Week 10
Prairie Crop Disease Monitoring Network - Week 11

Ticks and Lyme disease - Week 4

Weather Radar - Week 6
Wildfires - Week 8

Wind trajectories - Review Page for list of PDFs

Insect of the Week (June 24) - Doppelgangers: midge vs. parasitoid

The case of the innocuous versus the evil twin: When making pest management decisions, be sure that the suspect is actually a pest. This can be challenge since insects often mimic each other or look very similar. An insect that looks, moves and acts like a pest may in fact be a look-alike or doppelganger. 

Doppelgangers may be related (e.g. same genus) or may not be related, as in the case of monarch butterflies (Danaus plexippus) and viceroys (Limenitis achrippus).  Doppelgangers are  usually relatively harmless but sometimes the doppelganger is a pest yet their behaviour, lifecycle or hosts may be different. 

Correctly identifying a pest enables selection of the most accurate scouting or monitoring protocol. Identification and monitoring enables the application of economic thresholds. It also enables a producer to select and apply the most effective control option(s) including method and timing of application.  For the rest of the growing season, the Insect of the Week will feature insect crop pests and their doppelgangers.

Is that a midge or a parasitoid? Why does it matter?

Small insects (i.e., less than 5 mm) are difficult to identify, even for trained specialists and professional entomologists. Especially if they are alive, flying around. Or in a sweep net sample quickly assessed in the field. In the case of midge and small-bodied parasitoids, they can be easily mistaken for one another, but their roles in agriculture tend to be very different. 

Some of the most well-known prairie midge species are agricultural pests, such as the orange coloured wheat midge (Sitodiplosis mosellana), black-coloured Hessian fly (Mayetiola destructor), and alfalfa blotch leafminer (Agromyza frontella). Other midge species found on the prairies include biting midge like no-see-ums (Ceratopogonidae), black flies (Simuliidae), and non-biting midge (Chironomidae). Midge that are not considered agricultural pests may provide some ecosystem services (i.e., pollination), while other midge are disease vectors and are pests of medical and veterinary concern. 

A - Hessian fly – adult Scott Bauer, USDA Agricultural Research Service, Bugwood.org
B - Swede midge – adult
Susan Ellis, USDA APHIS PPQ, Bugwood.org
C - Wheat midge – adult
Mike Dolinski, MikeDolinski@hotmail.com

Parasitoids are natural enemies of other insects. Thus, many parasitoids are important because they help control agricultural pest populations. Adult parasitoids lay eggs, usually singly, onto or into their host. The larvae that hatch from the eggs develop using the host as food, and eventually kill the host. An individual host usually provides enough food for just one parasitoid larva. For this reason, parasitoids species are rarely larger in size than their host species. On the prairies, important parasitoid families that may be mistaken for midge or other small, black insects include: Aphidiinae, Braconidae, Chalchididae, Encyrtidae, Eulophidae, Platygasteridae, Pteromalidae and Trichogrammididae.

Sticky cards or sweep net samples may contain hundreds or thousands of small, black, winged insects. Many are probably parasitoids and not pests so look closely when scouting. A few key differences to watch out for include:

1.      Parasitoids have two pairs of wings while midge have only one pair of wings,

2.      Parasitoids are often shiny or metallic shades of black, blue, purple or green,

3.      Midge may look hairy; parasitoids rarely look hairy.  

1 - Aphidiinae – adult (Aphidius avenaphis) Tyler Wist, AAFC
2 - Braconid wasp – adult
Alberta Agriculture and Rural Development
3 - Chalcid wasp – adult (Phasgonophora sulcata) Michael Gates, Encyclopedia of Live, EOL.org
4 - Tetrastichus julis – adult parasitizing a cereal leaf beetle larva
Swaroop Kher, University of Alberta/AAFC
5 - Ichneumonid – adult (Banchus flavescens) John Gavloski, Manitoba Agriculture, Food and Rural Development
6 - Platygasterid – adult (Inostemma sp.)
Tyler Wist, AAFC
7 - Pteromalid – adult (Pteromalus puparum) Koorosh McCormack, Natural History Museum: Hymenoptera Section, EOL.org
8 - Trichogrammid – adult (Trichogramma sp.) parasitizing an egg

Jack Kelly Clark, University of California Statewide IPM Program

Specific information on these families of parasitoids and on the species of midge listed here can be found in updated Field Crop and Forage Pests and their Natural enemies in Western Canada field guide.

Review previously featured insects by visiting the Insect of the Week page.

Post contributed by Dr. Meghan Vankosky.