4 pp., 1 table, 2 color photosElm leaf beetles damage all varieties of elm trees.  Learn  how to identify this insect and understand its biology and life cycle.  There are suggestions for controlling elm leaf beetles, as well as a table of insecticides effective against this pest

Patrick, Carl D.

Texas A&M University

Elm Leaf Beetles
L-1812
5-02
Carl D. Patrick*
The elm leaf beetle, Xanthogaleruca luteola(Muller), was accidentally introduced intothe eastern United States early in the nine-
teenth century. It feeds on all varieties of elm
trees, especially Siberian and European elms.
However, feeding damage is much less evident
on varieties such as cedar elm, lacebark elm,
American elm and winged elm. Damage to these
varieties may be more severe if other elms the
beetles prefer are unavailable. The elm leaf bee-
tle is also known to cause some damage to
Japanese zelkova.
Id e ntification
Adults are about 1/4 inch long and light yellow
to brownish green. Several black spots decorate
the head and thorax, and a broad black stripe
follows the outer margin of each wing cover.
Overwintering adults are darker and duller than
summer adults. Eggs are laid in clusters of five
to 25  on the undersides of leaves; they are yel-
low-orange and pointed on the outer end, resem-
bling miniature lemons. Newly hatched larvae
are black. Mature larvae are pale yellow with
two black, interrupted stripes down the back;
they are about 1/2 inch long. Pupae are 1/4 inch
long and bright orange-yellow with scattered
black bristles.
Biology and Habits
Elm leaf beetles overwinter as adults in any
sheltered, dry place that gives them protection.
Overwintering adults sometimes enter homes,
where they become a nuisance on warm days.
The insects do not infest food or other household
materials, but simply spend the winter indoors.
In spring, beetles fly to elm trees shortly after
foliage emerges. They eat holes in new leaves
and soon deposit eggs. A single female may pro-
duce as many as 400 to 800 eggs. Slug-like black
larvae hatch in about a week. Larvae feed for
about 3 weeks on the undersides of leaves;
when mature, they crawl down the tree to gather
in large masses at the base of the trunk (or any
other nearby, sheltered place) to pupate. Adult
beetles emerge from pupae about 2 weeks later.
Three or more generations occur each year in
Texas. In late summer and early fall, the adults
begin to seek overwintering sites.
*Extension Entomologist, The Texas A&M University System.
Elm leaf beetle adult.
Damage
Elm leaf beetles feed exclusively on foliage.
Adult feeding causes small, circular holes in
leaves. Larval feeding removes most of the green
material from leaves, leaving them dry and
brown with only the leaf veins remaining.
Heavily infested trees have sparse foliage;
remaining leaves are riddled with holes, have a
rusty, reddish-brown tint and are likely to drop
prematurely. Severe infestations for several con-
secutive years can cause limbs or the entire tree
to die. Siberian elms are most severely attacked
by elm leaf beetles and most of the damage is
caused by first generation larvae. Young, devel-
oping leaves provide high quality forage for the
small beetle larvae. By the time the second gen-
eration is feeding, the leaves are mature and
there is less damage. Generally, the environmen-
tal conditions under which second and third gen-
erations develop are not as good as those for the
first generation. Elm leaf beetles do not transmit
Dutch elm disease.
Co ntro l
Natural
Natural enemies include birds, toads, diseases
and predaceous and parasitic insects. A small
wasp frequently kills many pupae. A fungus also
kills pupae and adults late in the summer, espe-
cially if the weather is humid. Unfortunately,
these natural controls are not often sufficient to
hold the beetles in check, so it is necessary to
use insecticide.
Foliar Sprays
Early detection of the beetles makes it possible
to spray trees before much damage occurs.
Examine the undersides of leaves for yellow eggs
and young larvae soon after leaves emerge in
April. Apply insecticides when most of the eggs
have hatched and the small larvae are just begin-
ning to feed. Make sure insecticide thoroughly
covers newly developing leaves. It may be neces-
sary to hire a commercial applicator, someone
who is properly licensed and equipped, to spray
tall trees. Insecticide applications may need to be
repeated to control later generations of beetles.
Systemic Applications
Another approach is to use systemic insecti-
cides, which can be applied as tree implants, soil
injections or granules. Systemic insecticides are
transported through the tree to the leaves. To
control the first generation of beetles, a systemic
insecticide should be applied in late March or
April.
Exclusion
Adult beetles can be excluded from homes by
placing tight-fitting screens over windows and
doors and closing all other openings. Spraying
outside walls and the perimeter of the house
with properly labeled insecticides may reduce
the adult population in the fall.
2
Elm leaf beetle larvae, egg mass and damage.
Elm Leaf Beetle Control Recommendations
Ingredient Trade Name
acephate Orthene® 
AceCap® 
Bacillus thuringiensis var. tenebrionis Novodor® 
bifenthrin Talstar® 1
carbaryl Sevin® 
chlorpyrifos Dursban® 2
cyfluthrin Tempo® 1
Decathlon®  1
cypermethrin Demon® 1,3
Cynoff® 1,3
disulfoton Di-Syston®  
imidacloprid Merit® 
Bayer Advanced Garden Tree & Shrub 
Insect Control
lambda-cyhalothrin Scimitar® 1
Demand® 1
permethrin Dragnet® 1,3
phosmet Imidan® 1
spinosad Conserve®  
tralomethrin Saga® 
1 For commercial use only.
2 Dursban products are no longer being sold. Use existing stocks as directed on the product label or learn how to dispose
of them by contacting your local or state hazardous waste disposal program.
3 Use on outside surfaces and around buildings only.
3
Insecticide labels are subject to change and changes
may have occurred since this publication was printed.
The insecticide user is always responsible for the
effects of insecticides on his own property, as well as
problems caused by drift from his property to that of
others. Always carefully read and follow the instructions
on the insecticide label.



English

Elm Leaf Beetle

Texas A&amp;M Repository

Elm Leaf BeetlesL-18125-02Carl D. Patrick*The elm leaf beetle, Xanthogaleruca luteola(Muller), was accidentally introduced intothe eastern United States early in the nine-teenth century. It feeds on all varieties of elmtrees, especially Siberian and European elms.However, feeding damage is much less evidenton varieties such as cedar elm, lacebark elm,American elm and winged elm. Damage to thesevarieties may be more severe if other elms thebeetles prefer are unavailable. The elm leaf bee-tle is also known to cause some damage toJapanese zelkova.Id e ntificationAdults are about 1/4 inch long and light yellowto brownish green. Several black spots decoratethe head and thorax, and a broad black stripefollows the outer margin of each wing cover.Overwintering adults are darker and duller thansummer adults. Eggs are laid in clusters of fiveto 25  on the undersides of leaves; they are yel-low-orange and pointed on the outer end, resem-bling miniature lemons. Newly hatched larvaeare black. Mature larvae are pale yellow withtwo black, interrupted stripes down the back;they are about 1/2 inch long. Pupae are 1/4 inchlong and bright orange-yellow with scatteredblack bristles.Biology and HabitsElm leaf beetles overwinter as adults in anysheltered, dry place that gives them protection.Overwintering adults sometimes enter homes,where they become a nuisance on warm days.The insects do not infest food or other householdmaterials, but simply spend the winter indoors.In spring, beetles fly to elm trees shortly afterfoliage emerges. They eat holes in new leavesand soon deposit eggs. A single female may pro-duce as many as 400 to 800 eggs. Slug-like blacklarvae hatch in about a week. Larvae feed forabout 3 weeks on the undersides of leaves;when mature, they crawl down the tree to gatherin large masses at the base of the trunk (or anyother nearby, sheltered place) to pupate. Adultbeetles emerge from pupae about 2 weeks later.Three or more generations occur each year inTexas. In late summer and early fall, the adultsbegin to seek overwintering sites.*Extension Entomologist, The Texas A&M University System.Elm leaf beetle adult.DamageElm leaf beetles feed exclusively on foliage.Adult feeding causes small, circular holes inleaves. Larval feeding removes most of the greenmaterial from leaves, leaving them dry andbrown with only the leaf veins remaining.Heavily infested trees have sparse foliage;remaining leaves are riddled with holes, have arusty, reddish-brown tint and are likely to dropprematurely. Severe infestations for several con-secutive years can cause limbs or the entire treeto die. Siberian elms are most severely attackedby elm leaf beetles and most of the damage iscaused by first generation larvae. Young, devel-oping leaves provide high quality forage for thesmall beetle larvae. By the time the second gen-eration is feeding, the leaves are mature andthere is less damage. Generally, the environmen-tal conditions under which second and third gen-erations develop are not as good as those for thefirst generation. Elm leaf beetles do not transmitDutch elm disease.Co ntro lNaturalNatural enemies include birds, toads, diseasesand predaceous and parasitic insects. A smallwasp frequently kills many pupae. A fungus alsokills pupae and adults late in the summer, espe-cially if the weather is humid. Unfortunately,these natural controls are not often sufficient tohold the beetles in check, so it is necessary touse insecticide.Foliar SpraysEarly detection of the beetles makes it possibleto spray trees before much damage occurs.Examine the undersides of leaves for yellow eggsand young larvae soon after leaves emerge inApril. Apply insecticides when most of the eggshave hatched and the small larvae are just begin-ning to feed. Make sure insecticide thoroughlycovers newly developing leaves. It may be neces-sary to hire a commercial applicator, someonewho is properly licensed and equipped, to spraytall trees. Insecticide applications may need to berepeated to control later generations of beetles.Systemic ApplicationsAnother approach is to use systemic insecti-cides, which can be applied as tree implants, soilinjections or granules. Systemic insecticides aretransported through the tree to the leaves. Tocontrol the first generation of beetles, a systemicinsecticide should be applied in late March orApril.ExclusionAdult beetles can be excluded from homes byplacing tight-fitting screens over windows anddoors and closing all other openings. Sprayingoutside walls and the perimeter of the housewith properly labeled insecticides may reducethe adult population in the fall.2Elm leaf beetle larvae, egg mass and damage.Elm Leaf Beetle Control RecommendationsIngredient Trade Nameacephate Orthene® AceCap® Bacillus thuringiensis var. tenebrionis Novodor® bifenthrin Talstar® 1carbaryl Sevin® chlorpyrifos Dursban® 2cyfluthrin Tempo® 1Decathlon®  1cypermethrin Demon® 1,3Cynoff® 1,3disulfoton Di-Syston®  imidacloprid Merit® Bayer Advanced Garden Tree & Shrub Insect Controllambda-cyhalothrin Scimitar® 1Demand® 1permethrin Dragnet® 1,3phosmet Imidan® 1spinosad Conserve®  tralomethrin Saga® 1 For commercial use only.2 Dursban products are no longer being sold. Use existing stocks as directed on the product label or learn how to disposeof them by contacting your local or state hazardous waste disposal program.3 Use on outside surfaces and around buildings only.3Insecticide labels are subject to change and changesmay have occurred since this publication was printed.The insecticide user is always responsible for theeffects of insecticides on his own property, as well asproblems caused by drift from his property to that ofothers. Always carefully read and follow the instructionson the insecticide label.

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Elm Leaf Beetle

Abstract

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Texas A&M University

Texas A&M Repository

Elm Leaf Beetle

Abstract

Similar works

Full text

Available Versions

Texas A&M University

Texas A&amp;M Repository

Texas A&M Repository