Rent Shop Volunteer Join

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
2 ratings

Sunday - July 28, 2013

From: Jacksonville, FL
Region: Southeast
Topic: Butterfly Gardens, Herbs/Forbs
Title: Effects or insecticide on Monarch butterflies
Answered by: Guy Thompson

QUESTION:

Thank you for fielding questions about plants!! Our nursery just informed us that their milkweed grower was using imidacloprid in their milkweed production. As a follow up to the question already in your database about imidacloprid on milkweed and its toxicity; Are NEW plants grown from 1) the stalks of denuded (by the poor caterpillars) plants and 2) grown from seeds from a imidacloprid treated plant - are those plants subject to the same half life time frame?

ANSWER:

The excerpt shown below must be the one you found in out database.

"Imidacloprid is a chemical to avoid if at all possible.  It is a synthetic analog of nicotine and is slow to degrade in the environment.  According to the National Pesticide Telecommunications Network, it has a half-life in sandy loam soil of greater than one year.  In bright light it degrades faster, with a half life of 39 days. But even the degradation products that form inside plants are highly toxic to insects, and their half-life is not reported.

Imidacloprid has been implicated in the mysterious colony collapse disorder of honeybees. For this reason, certain countries, e.g., France, has outlawed its usage for many purposes.

It seems safe to assume that milkweeds treated with imidacloprid may be quite toxic to monarch caterpillars for an extended period.  Mr. Smarty Plants recommends the use of much less toxic sprays, such as Safer soap, which may be less effective on aphids but harmless to monarch caterpillars."

The half life of the chemical will be the same no matter where it resides.  The main question is the quantity that the caterpllars eat.  Imidacloprid is a systemic compound, meaning that it moves throughout the entire plant and not just the parts sprayed.  There might be enough on the denuded stalks to injure the caterpillars when they eat new leaves that have drawn the insecticide from the old stalks.  But the amount of imidacloprid that might have entered the seed would be diluted so much in new plants grown from it that there should be no danger. The caterpillars would not ingest a large enough amount of the chemical to damage them. So the conservative solution is to start new plants from seed.

 

 

 

More Herbs/Forbs Questions

Planted bluebonnets won't prosper in Bluff Dale, TX.
April 24, 2013 - I have planted bluebonnet seed several years (this last year we planted inoculated seed) always the same results -germination, growth to 4-6 leaf stage, then very pale stunted growth, bronzing. soil t...
view the full question and answer

Plants for streambank area in Oregon
September 14, 2012 - I am ready to replant a streambank area with native plants..what do you recommend for the Willamette Valley in Oregon? Thanks much!
view the full question and answer

Shade tolerant groundcover plants for Tarrant County, Texas
November 01, 2011 - I live in far NE Tarrant County (Ft Worth), TX and need a groundcover that can tolerate complete shade and poor, rocky, clay soil. I need mostly for erosion control, and needs to be relatively low
view the full question and answer

Shade tolerant plants for erosion from Austin
May 03, 2014 - I live in Austin and my house backs up to Shoal Creek. I am looking for a native creeping vine or something that will grow on the shaded bank to help prevent erosion. It should be able to tolerate the...
view the full question and answer

Tropical Texas landscape from Houston
March 04, 2013 - Do you know of any public (or at least photographed) place in Texas that has been landscaped entirely with native "tropical-looking" (i.e. evergreen but NOT conifer and NOT succulent/arid) species? ...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.