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| Figure 1. Applying Tanglefoot to plastic. |
This week, we are busy making emergence traps for wheat midge so we can collect the the newly emerging adults from the soil. To do this, we spread a sticky substance called Tanglefoot onto a plastic sheet (Figure 1) then we cut it into strips. The strips will be mounted inside plastic buckets that have the bottoms cut off and will be pushed into the soil at our producer-cooperator fields. If the midges land on the sticky traps, they won’t be able to fly away and we will be able to collect them and determine how many have overwintered in the field.
I’ve learned that wheat midges are tiny flies that overwinter within cocoons in the soil. They emerge as adults over a 5-6 weeks period between mid-June to mid-July. They only live for four or five days but during that brief period the females lay eggs on the wheat flowers. When the eggs hatch, the larvae crawl within the spikelet (Figure 2) then feed upon the developing wheat kernel. They are highly concealed larvae, existing and feeding within the spikelet then, once the weather turns damp, the larvae drop to the soil to form their cocoon in preparation for overwintering.
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| Figure 2. Structure of wheat plant and head (Image: http://www.odec.ca/projects/2009/adam9s2/index_files/image1207.jpg) |
Typically, wheat midges are sampled using soil cores and by examining the plants for adults when they are laying eggs, but Amanda is doing research on other methods of monitoring this pest (as she writes about in her own post!).