Faronta diffusa in Alberta, Canada

Martha V. Lutz & Charles T. Lutz lutzrun at avalon.net
Wed Aug 2 13:31:26 EDT 2000

Hello . . . me again (Martha Rosett Lutz).  Dr. Johnson sent this to me
yesterday, saying it needed some editing and asking if I would please post
it to the Leps List.  (This is spooky--the same thing happened last time I
sent a long-ish note to the Leps List.  Immediately afterward he asked me
to post a note on his behalf.  Once again, how can I say 'no' to a good
friend who also is the current President of the Entomological Society of

Note:  Dan is trusting my 4+ years of experience as a professional writer
and editor, so I will say here that any errors or misspellings or just
plain bad grammar or syntax are my fault and I take full responsibility.
The science content is direct from Dan.


>From Dr. Daniel Johnson:

I'm taking a break to look briefly at an insect that has gone from rare to
common in local cereal fields.  (I believe that it is also rare in western
states of the US.)  Although we often find larvae of the rare Wheat head
armyworm (WHAW), Faronta diffusa, in southern Alberta (AB) mature cereals,
this year there are many other fields in which it is common (1-5 per 20
sweeps, and up to more than 3 per sweep).  At this time most local
populations are probably well below the economic threshold (which has not
been set), but the method and rate of feeding indicates pest potential. The
larva eats wheat kernels right out of the head, and feeds quickly.  (To see
an illustration of this, look at the completely empty head in the photo on
the website below; not the one at the top - that is a photo of me; I mean
the green empty head a little lower on the page).

As I understand from recent e-mails received from John Gavloski and Scott
Hartley, there are no reports of this species from Saskatchewan or Manitoba
yet this year.  As far as I know, there are no past reports of wide-spread
infestations (except spot occurrence in 1998).  In AB this year it seems to
be most common in wheat and barley, mainly in the fescue grassland
ecoregion, and to a lesser extent in the mixed grass ecoregion.  Yesterday
I was unable to find any WHAW in wheat fields near Foremost or Etzikom (SE
AB, dry mixed grass ecoregion).

I suspect that it is more common in southern Alberta because of the dry
warm conditions.  Conservation tillage probably provides greater
overwintering survival of the pupae.

It will probably be noticed at harvest time, and many cereals will escape
damage because of timing of harvest.

Dan Johnson
Aug 1, 2000

 Dan Johnson
 fax (403) 382-3156
 JohnsonDL at em.agr.ca


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