Ennomos subsignaria in Newfoundland

[Lawrence F. Gall]

Forwarding on behalf of Peggy Dixon, dixonpl at agr.gc.ca:

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Any help appreciated on the following:

Last year there was an outbreak of the elm spanworm in the city of St. 
John's, Newfoundland, sufficiently extensive that some homeowners cut down 
80 year old maples to get rid of the caterpillars and frass.  The 
insect  is not common here and we were not familiar with dealing with an 
outbreak on urban streets.  Our forests are mostly conifers so it has not 
been a forestry issue either.  We are in the middle of having neighbourhood 
meetings, radio interviews and so on as everyone anticipates another "bad" 
year.

We have been collecting branches and tree boles for egg mass counts and 
rearing.  Anyway, today I was counting eggs and egg masses and noticed that 
several of the egg masses contained empty eggs.  I know these are 
univoltine so is it possible that these overwintered last year, hatched in 
the spring of 2002, and are still attached to the tree?  Is this possible?

There were many more apparently intact egg masses than empty ones.  I tried 
to dissect a couple of eggs - not easy with a tough chorion and a tiny egg. 
They were filled with a greenish "soup" - no larval differentiation obvious 
at all, but the contents looked healthy.

In 2002, late instar larvae were present in July and moths in August.  In 
2003, the spring has been cold so I am not expecting egg hatch yet.  We are 
monitoring this under controlled conditions.

Any advice appreciated, especially about whether the empty egg masses could 
have been there since being laid in the fall of 2001.  If not, is there 
another explanation??

Thanks,

Peggy Dixon

Peggy L. Dixon, PhD
Entomologist/Entomologiste
Environmental Health/Santé de l'environnement
Integrated Pest Management/Lutte intégrée
Agriculture and Agri-Food Canada/Agriculture et Agroalimentaire Canada
Telephone/Téléphone: 709-772-4763
Facsimile/Télécopieur:  709-772-6064
308 Brookfield Road/308, chemin brookfield
P. O. Box 39088 / C.P. 39088
St. John's, Newfoundland and Labrador
A1E 5Y7, Canada
dixonpl at agr.gc.ca

......................................................................
: Lawrence F. Gall, Ph.D.            e-mail: lawrence.gall at yale.edu  :
: Head, Computer Systems Office &     voice: 1-203-432-9892          :
: Curatorial Affiliate in Entomology    FAX: 1-203-432-9816          :
: Peabody Museum of Natural History    http://www.peabody.yale.edu   :
: P.O. Box 208118, Yale University                                   :
: New Haven, CT 06520-8118 USA                                       :



 
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