I haven’t been able to find much about control of cypress tip moth on true cypress (Cupressus). I’m looking for a non-toxic control instead of the WSU recommendation of Orthene. Would Neem possibly work? Spinosad? Both are registered for leaf miners (fly larvae), but this is a moth larvae. Bt (Bacillus thuringiensis) won’t work because the larvae are inside of the foliage. What’s the best timing for a non-toxic? WSU recommends controlling the adults in July-August.
University of
British Columbia Botanical Garden’s forum has this to say:
“In the west, cypress tip moth sometimes infests cypress (Cupressus and
Cupressocyparis) and false cypress (Chamaecyparis); those are also
sometimes called cedars. In the east, cedar often refers to Juniperus
(red cedar), Thuja or Chamaecyparis (white cedar); all are subject to
bagworm infestations and various tip-miners. In the west, timely shearing
is the most effective way to control cypress tip moth, and this may also
be a tactic in other parts of North America.
“In many cases, infestations occur because there are few natural enemies
about to reduce pest levels. Sometimes, pests are attracted to plants
that are already weakened by stress. Healthy plants and diverse
plantings, together with a reduction in pesticide use, will over time,
increase beneficial organisms which will in turn reduce pest levels.
Spraying to reduce pests generally affects beneficials to a greater
degree than the actual target pest. This is because pest species often
have a greater capacity to rebound — they often reproduce faster, have a
greater tolerance for pesticide residues and have a greater capacity to
become resistant to pesticides.”
Oregon State University’s IPM site only mentions chemical controls.
From an online forum, ‘Horticulture Guy:’
Q. I have a row of 16 – three year old “Emerald Green” arborvitaes. I
suspect they have arborvitae leafminer (cypress tip moth). I have
noticed the moths before, but now there are more and I just recently
noticed brownish-yellow tips on a couple of the trees. All of them have
lots of needles falling from the interior. My problem is that I have
received conflicting reports about the proper time to spray for them, and
is there anything I can do in the meantime to lesson the damage? Thank
you! Linda Brieger – Tacoma, WA
A. The way to gain control over any pest population is to know its life
cycle. Spraying is geared toward eliminating the adult form of the
insect, which is a moth as the second of the two common names indicates.
The most likely reason you may see conflicting reports on when to spray
the moths is because of varying times the moth may emerge in different
regions where they are present. They are generally active in our area
from April to June with a peak of activity in May. The moths lay their
eggs during this period and the eggs hatch and then burrow into the
needles of the host plant. According to the WSU extension the adult
moths are silver-tan and approximately 1/4″ in length. External sprays
won’t have an effect on the larvae once they burrow so you need to spray
weekly during this period to catch the larvae as they hatch. Systemic
insecticides are able to kill the larvae once they are in the host. You
can limit systemic insecticide spraying to one application near the
beginning of the activity since they generally remain effective for some
time (see labels for instructions). As far as “in the meantime” a
sprayless solution is to prune out and destroy infected parts of the host
now so that there are less moths in the spring. You can also keep an eye
out in the spring for the white cocoons that form after the larvae exit
the host to become adult moths. You can remove these as well.
University of California Integrated Pest Management suggests that proper
cultural care and removal of susceptible plants is the answer. Excerpt:
Provide proper cultural care to keep plants vigorous. Prune out and
dispose of foliage infested with immature leafminers to restore the
plant’s aesthetic appearance and provide some control. Consider replacing
plants especially susceptible to the cypress tip miner. High populations
and damage can be reduced on established plantings by applying a
broad-spectrum, persistent insecticide such as acephate on susceptible
varieties when adult moths are active. Beginning in early spring, examine
foliage tips for the cocoons. When these appear, vigorously shake foliage
and watch to see if silvery tan, tiny moths fly up then settle back on
the foliage. One application to foliage can be made when a large number
of tip moths appear, between March and May in California. This reduces
browning next season.
You could try using the Neem oil (instead of the more toxic alternatives)
although I did not find any information specifically suggesting this as a
control for cypress tip moth. The WSU book, Pacific Northwest Landscape
IPM Manual (2002) suggests natural parasites which attack this species of
insect, but they do not specify the identity of these predators. They
state that there are no “biorational pesticide management options” for
this pest.