Manitoba Insect Update

June 2, 2008

Compiled by: John Gavloski, Entomologist, Manitoba Agriculture, Food and Rural Initiatives,
Crops Knowledge Centre, Phone: 204-745-5668; Fax: 204-745-5690

To report observations of insect activity or control that may be of interest or importance to others in Manitoba, please send messages to the above contact addresses.

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Summary

Cutworms have been a concern in some fields in the central part of Manitoba. Diamondback moth traps have only been catching very low numbers so far.

Recent Insect Concerns and Observations

Cutworms: Some cutworm problems have been noted in fields in the Central part of Manitoba. Highest population have been reported near Portage la Prairie and west of Cypress River. Some barley, sunflower and potato fields have been treated with insecticides to control cutworms. The species of cutworm involved seems to vary with the field encountered. Dingy cutworm has been one of the more common species this year. Below are pictures of dingy cutworm and redbacked cutworm. If you use a magnifier, you should be able to see the 4 spots of equal size per segment on the dingy cutworm, as well as what look like “v”-shaped markings on each segment. Note the thin white line down the middle of the redbacked cutworm, and the thicker reddish bands.


Dingy cutworm	Redbacked cutworm

Surveys and Forecasts

Diamondback moth: Counts of adult diamondback moth have remained very low across Manitoba. Only a few traps have reported any diamondback moths captured, and these counts have been either 1 or 2. Thus the risk from diamondback moth is currently low. Data from the diamondback moth trapping program and an interpretation of the data are available at: https://www.gov.mb.ca/agriculture/crops/insects/db/index.html

Bertha Armyworm: Traps for monitoring adults of bertha armyworm can now be set up. The protocol for setting up traps to collect bertha armyworm is on the MAFRI website at: https://www.gov.mb.ca/agriculture/crops/insects/fad59s00.html

Wireworm Survey: A national survey is being conducted to determine what species of wireworms are most abundant. It would be great if we can get as many samples as possible sent in from Manitoba. This will be very valuable data, because it has been shown that some of the newer seed treatments for wireworms do not work equally well on all species of wireworms. If you come across wireworms, save a sample to contribute to the survey. You can place the wireworms in a container (pill bottle, film canister, etc.) with a bit soil and send them to: Dr. Bob Vernon, Pacific Agri-Food Research Centre, P.O. Box 1000 – 6947 #7 Highway, Agassiz, B.C., V0M 1A0. Remember to include some details regarding the location the sample is from, the date it was collected, and the crop that was being grown in the field. Samples can also be dropped off or sent to me at the MAFRI office in Carman.

Coming our Way? Insect Summary from U.S. North Central States

Kentucky has reported extremely large collections of adult armyworm moths. According to their reports, these have been the highest captures they have recorded. These moths are also being captured in Ohio in relatively high numbers, and small larvae are already feeding on crops there. With these higher moth collections, growers should be aware that given the right conditions armyworms are an insect that can potentially be a concern in Manitoba. They do not overwinter in Manitoba, so the adult moths would have to get moved in on winds from the south. But considering the very high numbers to the south, this is something to watch.

Insect Identification Quiz


Caption: A	Caption: B

Question: These insects were both found while digging in the soil. Which of these insects is a wireworm?
1) A 3) Both are wireworms
2) B 4) Neither are wireworms

Answer: The insect in photo B is a wireworm. The insect in photo A is the larvae of a fly called a stiletto fly. These are sometimes referred to as therevids, from the name of this family of flies. Therevid larvae are predators and are quite active. They will thrash around a lot when disturbed, something wireworms won’t do. Also notice the lack of legs in the therevid larva. Wireworms have 3 sets of small legs near the front.

I have had several samples or pictures of Therevid larvae sent in this year. Apparently their populations are high in some areas. Don’t confuse them for wireworms.