Timed insecticide treatments
A persistent insecticide may be applied
to foliage to control black vine weevil adults, but monitor
weevil populations beginning early in the spring before spraying.
If you can tolerate some foliage damage, do not spray until
3 or 4 weeks after first detecting feeding damage or weevils;
few if any weevils will have laid eggs before then because
snout beetles must feed for about a month before they start
laying eggs. If adult feeding cannot be tolerated, spray
about a week after first detecting adults or damage. The
most effective time to make a single application to foliage
is as soon as your regular sampling for adults indicates
that weevil populations have peaked and begun to decline.
If weevil emergence is prolonged, a second foliar spray may
be warranted about 3 to 4 weeks after the first application.
Adult black vine weevil