CAUTION: This information
was developed for North Carolina and may not apply to other areas.
European fruit lecanium, Parthenolecanium corni (Bouche);
European peach scale, Parthenolecanium persicae (Fabricius); Fletcher
scale, Parthenolecanium fletcheri (Cockerell); oak lecanium scale, Parthenolecanium
quercifex (Fitch); Coccidae; HEMIPTERA
Female lecanium scales are 2 to 6 mm in diameter.
When fully grown, female scales are rounded, reddish to dark brown and
sometimes have a pale waxy bloom. Male scales are flying insects (each
wing is about 2 mm long) which are brown. Males have a long "tail" called
the style, and they have two white hairs that trail from the body. Eggs
are almost white and are 0.25 to 0.35 mm long. The eggs resemble fine pollen.
New nymphs are called crawlers. Crawlers are flat, pale insects with conspicuous
legs and antennae. Older nymphs are flat and brown. The legs and antennae
become less noticeable as they mature. Males develop into a pupal stage
that is a pale peach color and is covered by a translucent waxy coat.
Lecanium scales are found throughout North America, and many kinds of trees
can be infested with lecanium scales, but dogwoods and oaks are the most
frequently reported hosts. Lecanium scales suck sap from the leaves and
twigs of trees. They excrete honeydew, Severe infestations may stunt plant
development and cause premature leaf drop and small flowers. Sooty molds
may also develop on the honeydew.
Lecanium scales lay 1,000 to 5,000 eggs each in April and May.
These hatch and crawlers move to the leaves where they feed until late
summer. The nymphs molt into the second instar which moves
back to the twigs to spend the winter. They hibernate under a thin,
waxy shield. Males usually pupate and emerge in early spring. Some lecanium
scales can lay fertile eggs without mating. As adult females mature, they
become rounded and hardened. As the eggs are laid, the body of the scale
shrinks against the outer skin to form a protective shield over the eggs.
Optimizing tree growing conditions is always best. Perform a soil test,
irrigate during drought, avoid soil compaction beneath trees, remove turf from
beneath trees to avoid competition and excessive fertilization. Apply pesticide
sprays only if necessary and only to the crawlers. These scales are not easily
eradicated. The scales on the twigs are protected from pesticides
by the thin waxy covering or the adult scales are less susceptible to pesticides.
However, the crawlers are unprotected. By mid-June, most of the eggs should have
hatched and most of the crawlers should be on the leaves. The following pesticides
are labeled for scales or scale crawlers and can be used for Lecanium scale control:
75% soluble powder
10% wettable powder
50% wettable powder
80% soluble powder
20% wettable powder
systemic; may be appropriate in some settings
25% water soluble packets
57% emulsifiable conc.
25% wettable powder
23% flowable concentrate
*horticultural oil alone or + malathion
hort oil alone provides the fewest off-target effects
* Suitable for home use. There may be additional chemicals available.
For assistance with a specific problem, contact your local North Carolina
Cooperative Extension Service personnel.
Published by North Carolina Cooperative Extension Service
Distributed in furtherance of the Acts of Congress of May 8 and June 30,
1914. Employment and program opportunities are offered to all people regardless
of race, color, national origin, sex, age, or disability. North Carolina
State University at Raleigh, North Carolina A&T State University, U.S.
Department of Agriculture, and local governments cooperating.