On 14/05/2015 18:54, Emery Davis wrote:
Anyone have an idea about how long a pyrethrin-based bug spray would take
to work on viburnum beetle larvae? My viburnum opulus has been
skeletonised the last several years, this year I saw the caterpillar-like
beasties at work and sprayed. Two days later there were still lots
alive, I sprayed again. A day later they're still not dead but may have
stopped eating. Do I need to switch to a more noxious product?

Fraid so if you want them dead reliably. Or you could pick them off one
by one with tweezers which would be the only true Organic(TM) way.

This is a rooted cutting, now quite large, but my friend who gave it to
me is unaffected by the bugs!

-E

A simple organophosphate contact knock down will probably still work on
them but you have to swap every couple of years to avoid resistance. I
have never had too much bother with caterpillars unless I failed to spot
them but red spider mite has been a real problem in the greenhouse.

--
Regards,
Martin Brown