West Coast Nut September 2019

are vulnerable to crop loss or damage
from LFB.
Tollerup said he has seen a 50 percent
almond crop loss in an orchard where
LFB feeding early in the growing season
caused nuts to drop from the trees.
Leaffooted bug species include
Leptoglossus zonatus, L. clypealis and L.
occidentalis. Their name comes from the
small, leaf-like projections on their hind
legs. Adults in all three are about 0.75
to 1 inch long and have narrow brown
bodies with a white zigzag pattern
across the wings. Zonatus, which has
become the dominant LFB specie in the
San Joaquin Valley, can be identified by
two yellow spots just behind the head.
Overwintering
Leaffooted bugs’ overwintering capability
can lead to high populations in
the spring. This insect pest can tolerate
temperatures down to 21 degrees F for
six hours, Tollerup said. Milder winter
weather and this species’ ability to find
shelter are factors in higher infestation
rates in orchards. This pest is commonly
associated with pomegranates that
provide a feeding/reproduction site after
nut harvest. But, it is also finds shelter
in ornamental perennial plants including
palm and cypress trees. These pests
also seek shelter in eucalyptus trees and
outbuildings.
Almond and pistachio orchards
adjacent to riparian sites and other
prime overwintering sites are more
likely to suffer LFB feeding damage,
Tollerup said.
Last year, Tollerup said he was in a
fifth-leaf almond orchard adjacent to
a somewhat neglected pomegranate
planting. The orchard lost half its crop
due to a large population of LFB feeding
on the nuts early in the season.
Overwintering sites that provide adequate
shelter are springboards for the
next generation of LFB to hatch in the
spring. Adult LFB that survive winter
can lay more than 200 eggs in string like
strands on host plants. Nymphs emerge
from the eggs about one week later and
develop into adults in 5-8 weeks. Adults
can lay eggs over an extended period,
creating a population that includes
all life stages by late June. During the
spring and summer there are typically
two to three generations of LFB. In
the fall, all LFB develop until they
become adults. These will overwinter in
aggregations.
Adult leaffooted bugs’ mouthparts
can pierce developing nuts to suck
out juice. These mouthparts comprise
more than half their length and allow
them to probe deep into fruit in search
seeds. Nymphs have less of an impact
when feeding, generally only extracting
plant juices. According to UC IPM
Guidelines, LFB excretes digestive
enzymes when feeding to liquefy a
small part of the seed so that it can be
ingested. Tollerup hypothesized that
the enzyme also stains the pellicle of
almond kernels.
Management of LFB
Tollerup said almond growers and
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September 2019
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