Here are the questions most farmers ask about orange wheat blossom midge (midge), and the answers we provide at the Solutions Center.

Q: What do wheat midge adults look like?

A: Wheat midge is a very small, fragile orange fly about 2-3 mm (1/8") long. Its head is almost completely covered with two jet black eyes. The oval-shaped, transparent wings are fringed with fine hairs and it has six relatively long legs. If you see something actively flying in the crop during the day, it's probably not a wheat midge. Wheat midge adults are not strong flyers. They are only active in the crop just prior to and after sunset. When they fly, they tend to flutter from place to place. When resting on the plants they orient themselves with their head pointing upwards. After dark they are the only small orange fly resting on wheat heads.

Q: Is the orange-colored fly I saw in the wheat this afternoon a wheat midge?

A: If you saw an orange colored fly in the crop during the day, it's probably a lauxanid. The lauxanid, Camptoprosopella borealis is very common in wheat fields during the day and early evening. This fly is 2.5 to 4 mm in length, robust and yellowish-brown in colour. It is a strong flyer and when disturbed during the day, it will fly above the crop canopy. During the day, it is usually observed resting on leaves or on awns with its body oriented in the horizontal position or with its head pointed towards the ground.

Q: When should I check my wheat for wheat midge?

A: Wheat should be monitored every evening from the time the wheat heads emerge from the boot until they have flowered, as evident by a pair of anthers extruded from a single florets in the center of the wheat head. Monitoring should begin just prior to sunset and continue as long as the temperature is greater than 20 degrees C and the wind is less than 6 mph and the economic threshold has been reached.

Q: How do I determine if I have enough wheat midge in my crop to justify applying insecticides?

A: Wheat midge is a difficult insect to determine its densities in a wheat field. There have been a number of methods used by producers over the years, including sweeping an oil covered pie plate through the crop and counting the number of midge adhering it. Most methods being used are not very precise.

The most dependable monitoring method requires you to go out into the wheat field after it has started to head and to count the number of adult midge laying eggs on the wheat after sunset on warm, calm evenings. If the economic threshold is exceeded, insecticide application should be applied within four days of having reached the threshold.

Q: What is the best plant growth stage to apply insecticides to control wheat midge?

A: The best plant stage to apply Lorsban* is when the wheat crop is about 70 per cent headed. At this plant growth stage, the head on the main stem is fully emerged, the head on the first tiller is about one-half to two-thirds emerged and very few tillers will have flowered. This should provide the maximum number of unflowered wheat heads to apply insecticide to and kill the eggs deposited on the wheat heads four days prior to the insecticide application.

Q: Is it too late to apply Lorsban if the crop is 30 per cent flowered?

A: Applying Lorsban to a crop that is 30 per cent flowered will provide some crop protection. The amount of protection provided will be determined by how many days they have been laying their eggs on the plants. If the eggs have been on the plant for more than four or five days, the eggs will have hatched and once the emerging larvae have attached themselves to the developing seeds they will be unaffected by an insecticide application.

Q: When is the best time of day to apply insecticides for wheat midge control?

A: Evening application of Lorsban for midge control has been a standard recommendation since the early 1980s. The evening application was recommended because wheat midge adults are more active during the evening and Lorsban applied during the evening left higher residues on the plants when compared to applications made prior to noon. But as larger and larger areas required treatment, it became impossible to treat all the infested acreage during the evening and early morning application became more common. The morning application appears to provide adequate control, but studies comparing the time of application and the level of control have never been undertaken. Both evening and morning application appear to provide satisfactory results.

Q: Do adult midge cause damage?

A: No. They are self-sufficient, do not eat and are present only to lay eggs.

Q: When do wheat midge populations peak?

A: Wheat midge continues to develop in the soil. Peak populations should emerge between July 10th and 20th.

Q: Why are there two Lorsban rates for wheat midge?

A: The higher rate of 405 mL/acre should be used when aerially applying Lorsban and when ground applying the product into a thick, dense crop canopy. The lower rate of 336 mL/acre should only be applied by ground application into a thinner or average crop canopy.

Q: Are triticale and winter wheat susceptible to damage from wheat midge?

A: Yes. Similar thresholds as hard red spring wheat would apply to both triticale and winter wheat. Following the completion of the flowering process, further susceptibility levels of these two crops in unknown.

Q: I have my own weather station. How many degree days do midge generally need before they begin to appear?

A: Male wheat midge start emerging after 660 growing degree days base 5 degrees C; females start emerging after 700 growing degree days base 5 degrees C.

Q: How does Lorsban control wheat midge?

A: Lorsban controls the adult wheat midge by contact and inhalation. Both of these are immediate activity. Activity on the eggs has not been scientifically proven, however we do believe the vapor and contact residual activity both play a role. The vapor is believed to penetrate the eggshell resulting in activity. Eggs that are not controlled in this manner may also be have the larvae controlled immediately as they hatch from the egg. Once the larvae have penetrated the wheat kernel - the damage is done, thus control is no longer warranted.

Q: Is there a minimum/maximum temperature limitation to spraying Lorsban?

A: Temperature restrictions such as those found on pyrethroid (Decis™) labels are not applicable to Lorsban. Specifically for wheat midge, applications are not recommended at temperatures below 15 degrees C due to wheat midge being inactive and deeper in the crop canopy.

Q: What does the wheat midge parasite look like?

A: The main wheat midge parasite in western Manitoba and Saskatchewan is Macroglenes penetrans. It is a small, black wasp about 1 to 2 mm long. It overwinters within the larval stage of the wheat midge. In the spring, the wasp larva develops rapidly and kills the overwintering midge larva. The first adults emerge about a week after the wheat midge emergence begins and continues for about a month. Upon emerging they mate and seek out midge larvae in which to deposit their eggs. Annually, this parasite controls about 25 to 40 percent of the overwintering midge population.

Q: What affect will insecticide application have on the small, parasitic wasp that attacks wheat midge?

A: Insecticides applied to control wheat midge will affect its parasite, Macroglenes penetrans (Kirby) negatively. How much it affects it is related to local cropping practices and when the insecticides are applied. Where producers use crop rotation practices and apply insecticides at the right time, the impact should be minimal. Where crop rotation is used, the parasite emerges from last year's wheat stubble and migrate into this year's wheat fields in search of midge eggs. Because the parasite population emerges after the wheat midge, only a small proportion of the wasp population will be in the wheat field when the insecticides are being applied.

Q: Do dragonflies eat wheat midge adults?

A: If dragonflies feed on wheat midge adults, they do not consume very many. Dragonflies hunt during the day and wheat midge begin flying in the evening about the time dragonflies quit flying.

Q: How do I monitor wheat midge using sticky traps/cards/pie plates?

A:(answer from Lloyd Harris) Since the early 1980's, the recommended method for monitoring wheat midge has been to visually inspect wheat heads for egg laying midge on warm, calm evening just prior or after sunset after the crop has started to head. Monitoring continues every evening for an additional week to ten days until threshold populations have been reached or until anthers are visible on at least one floret in the center of wheat heads throughout the crop. For Glenlea wheat, monitoring continues until about 30 per cent of the florets on each head have exposed anthers.

Producers use this monitoring technique to estimate wheat midge populations but they do not like it, with good reason. Looking for these small insects at twilight or in the dark with a flashlight while fending-off the mosquitoes has made this one of the least welcomed tasks on the farm. And to make things worse, most producer's fields are spread over several miles and they may all need to be inspected at the same time.

To avoid having to inspect crops at night, producers have sometimes placed foam pie plates coated with vegetable oil on stakes throughout the crop to monitor their crops for wheat midge, but with varying success. After trying the "sticky-pie-plate" technique, most producers usually go back to visually inspecting their crops at night.

Last year, scientists with Agriculture and Agri-Food Canada evaluated a new version of technique. Instead of pie plates covered with oil, they used 10 sticky cards about the size of playing cards covered with a petroleum-based resin similar to Tanglefoot' placed several meters within the crop after heading. Cards were left in the fields for three days before they were examined.

Preliminary results are now in.

• No midge on the cards means population levels are too low to detect and are probably not economical.
• One to five midge on the ten cards is probably a concern.
• More than five midge on the ten cards indicates a serious problem.

The sticky-card, research results are promising but preliminary. In Manitoba and Saskatchewan, many areas have enough midge to give positive results using the sticky card technique. Producers considering using the Agriculture and Agri-Food Canada monitoring technique before these experiments are completed should continue using the existing recommendations when determining the need to apply insecticides for midge control. Until the research is completed, it should be view as interesting but experimental.