Bt references

[Paul Cherubini]

I can confirm that Mourning Cloaks do use elm trees.  I have found
colonies of mourning cloak larvae on elms planted along a road in Reno,
Nevada. I have also raised mourning cloak larvae on cut elm branches.

However, I do not agree with Semjase that spraying Bt could drastically
reduce mourning cloak butterfly populations. If there was such a thing
as a formulation of Bt was that effective against any common and nearly
cosmopolitan species of lepidoptera, the company that made it would be
wealthy beyond belief.

As a side note, the mourning cloak is one of our most successful urban
butterflies. For example, it is a frequent sight in Los Angeles and
Mexico City.

Paul Cherubini, El Dorado, California
paulcher at concentric.net