Insecticides and Crop Scouting - Parrish and Heimbecker, Limited

Scout to Spot Insect Outbreaks Early

Be prepared, but check thresholds before you spray

Crop scouting is the best way to get to know field conditions, identify insects present, determine threshold levels, and know when to act to protect yield. It’s the economically and environmentally sound prerequisite to making pest management decisions, reducing uncertainty, and ensuring you spray only when necessary. By utilizing Integrated Pest Management (IPM) strategies, you can control and prevent problems before they occur.

Familiarize yourself with problematic and beneficial species 

It’s important to develop tolerance for insect presence in your crops. Get to know both the problematic and beneficial species. Not every insect is there to cause harm. Many help, acting as natural predators to protect your crop or pollinating your plants. Terrestrial and avian animals also provide pest control—birds eat worms and grasshoppers, for example.

Crop scouting can help you build both knowledge and tolerance, and be prepared when action is truly necessary. Talk to an agronomist trained in thresholds and beneficial species, and ensure they are not focused on boosting product sales. When you must spray, time your application to protect beneficial insects. Otherwise, spraying may destroy those too, making the situation worse when pests move back in and there are no natural predators left to control them.

Carry a scouting kit  

Carry a scouting kit that contains the tools you’ll need to collect, record and preserve samples: clipboard, paper, pen, tweezers, paper or clear plastic bags, 10X magnifier, sweep net, pocket knife, flagging tape, and a pest identification guide. (Field heroes has an excellent FREE guide that can be ordered here).

Scouting tips 

  • Begin scouting weekly at emergence, more often in higher value crops and those more susceptible to attack. 
  • Assess overall field appearance, then check edges, centre, low and high areas.
  • Choose an appropriate scouting pattern, considering the field shape and ease of access, such as a W, X, Y or Z pattern (for uniformly distributed insects). 
  • Check specific areas for insects that populate those (high, low, wet or dry sections). 
  • Count mobile insects based on number present per square metre. 
  • For less mobile insects, shake the plant and count them on the ground.  
  • Swing a sweep net at arm’s length through the canopy to sample mobile or small insects (such as lygus bugs). 
  • Check plants from roots to shoots, on upper and lower sides of leaves, flowers and pods, for damage or abnormalities. 
  • Check at least five locations in fields under 100 acres, at least 10 in larger fields. 
  • If you find something suspect, contact your P&H Representative to help with assessment. 

Insects to be aware of this year are:  

Grasshoppers – Hatching is wrapping up and they should be in the nymph stage. If you have very high populations, now is the time to control. 4 species to be keep an eye on: 3 generalists (feed on all crops) migratory, Packard, and twostriped. And clearwinged hoppers which prefer cereals/grasses. General note: if size of grasshoppers is over ½ inch by middle of July and seeing populations of 10+/m2 it may be time to spray. There are many species on the prairies so proper ID is important, majority are not crop pests. Thresholds by crop can be found here. BeneficialsBee flies, Flesh flies, Ground beetles, Tachinid flies  

Wheat midge – With late seeding across the Eastern Prairies, this many be more of an issue this year. If you still have some fields between heading and flowering, you should be scouting for them in the evening (dusk). Beneficials: ground beetles, Macroglenes penetrans  

Diamond back moth – Keep an eye out for them when scouting canola from now through August. If you are seeing some, gently pull plants and shake/bang against something (truck hood) to dislodge and get a larvae count. BeneficialsCotesia spp., Damsel bugs, parasitoids, green lacewing 


WANT TO STAY UP TO DATE? Check out the Prairie Pest Monitoring Network’s weekly update.

Treat problem pests when thresholds are present 

Your P&H Representative can help you identify insects and provide treatment recommendations. P&H provides a variety of pest management options from suppliers such as BASF, Corteva, FMC, Bayer, Syngenta and Nufarm. Contact your local P&H to discuss crop protection products that fit your farm.