of Rhode Island GreenShare Factsheets
The adult pear psylla looks somewhat like a tiny cicada.
Early season adults are small, 2.12 mm (1/10th inch) in length,
and are a dark reddish brown color with black bands on the
abdomen. The wings are held roof-like over the sides of the
body and are nearly translucent. Eggs are yellowish orange
and may be seen with the aid of a hand lens in creases of the
bark. Newly hatched nymphs are yellowish and only 1/4 mm (1/80
inch) in length! Late-stage nymphs are hard shelled and wing
pads may be seen forming. Adults of summer generations may
differ from those of the hibernating generation being about
one third smaller and having brighter (tan to light brown)
coloring and different wing markings.
Adult psyllas overwinter on the trunks under flakes of
bark or in crevices. If they are abundant, they may also be
found under leaves on the ground. Adults emerge with the onset
of warm weather (40 to 50 degrees F) in the spring, mate, and
begin laying eggs when temperatures reach 50-60 degrees F.
Yellowish-orange eggs are deposited in crevices in the bark
and near the terminal buds. Most of the eggs will have hatched
by the time the flower petals fall. Young nymphs migrate to
the axils of leaf petioles and of forming fruit. As these sites
become overcrowded, the nymphs move on to the undersides of
the leaves. Five immature (nymphal) stages are passed through
before the winged adults appear. There are three to four generations
of the pear psylla per year. Females of the later generations
will deposit most of the eggs along the leaf midribs. One female
pear psylla may deposit up to 500 eggs.
The pear psylla attacks all varieties of pears and may
occasionally attack quince. It is a sucking insect and feeds
on the plant sap. Heavy feeding plus the injection of toxic
saliva by pear psylla may cause early defoliation and loss
of the fruit crop. The nymphs secrete a sticky substance known
as honeydew as they feed. A black sooty mold fungus forms on
this honeydew and may cause damage by interrupting the normal
process of photosynthesis. A roughening or 'russet' of the
skin occurs on the fruit.
Look for adults on the spurs and branches of the tree
during warm days just prior to bud burst, and on the tender
new shoots from green cluster through the remainder of the
season until leaf drop. Eggs in the late dormant to bud burst
stages are found singly or in rows on spurs and twigs, or around
bud scales. Through the remainder of the growing season, look
on tender new growth for rows of eggs along the leaf midribs
and especially the undersurfaces. Small nymphs are found from
green cluster throughout the season on tender new growth, larger
nymphs are found on leaves that are hardening off.
Natural enemies such as lady bird beetles, lacewings,
and syrphid fly larvae are often present but they seldom keep
populations low enough to prevent injury. Apply oil as adults
are emerging, but before egg laying has occurred (as soon as
adults are present and temperatures exceed 50 degrees F.) Timing
will vary each season. The most important times to treat for
pear psylla are at the pre-bloom (white bud) and petal fall
stages. Apply a multipurpose fruit tree spray mixture (note:
multipurpose mixture often contains malathion, captan and methoxychlor)
or insecticidal soap at white bud, at petal fall, and as needed
based on monitoring during the growing season. Insecticidal
soaps are made from biodegradable fatty acids and are contact
insecticides that can provide suppression of pear psylla when
used in a seasonal spray program. Their residual period is
short, however, and uniform drying conditions are required
to prevent droplet residues on the fruit surface.
Adapted from the
Cornell Cooperative Extension, 1999
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
of Rhode Island Cooperative Extension provides equal program