Thursday, 14 July 2016

Weekly Update (July 13, 2016; Wk 11) - Grasshoppers

Grasshoppers (Acrididae) – Across the prairies, the predicted mean instar of Melanoplus sanguinpes is 4.5 with adults appearing in many areas across the prairies.  In central Saskatchewan, grasshopper development continues to be more than 2-3 weeks ahead of average development. 

The following graph shows grasshopper development at Saskatoon for 2016. The model indicates that fifth instar numbers are beginning to peak and that adult grasshopper densities are increasing. 

The second graph below illustrates grasshopper development (for Saskatoon) based on LTN data. Based on average weather, the population should be primarily in the third instar and fourth instars with increasing numbers of fifth instars.  Adults are not predicted to occur until July 19. 


- The following image showing various stages of Camnulla pellucida is provided below - note that adults have wings extending the length of the abdomen whereas nymphs lack wings but develop wing buds that will eventually mature to wings.  

Figure 1. Life stages of Camnulla pellucida which including eggs, first-fifth instar nymphs and adult (L-R).

- Generally, the economic threshold for grasshoppers in cereals is 8-12 per square metre but will vary by crop and growing conditions.

Biological and monitoring information related to grasshoppers in field crops is posted by the provinces of ManitobaSaskatchewanAlbertaBritish Columbia and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the new "Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide" - both English-enhanced or French-enhanced versions are available.