Summer Insects and Diseases
Locust Twig Borer
Cottony Maple Scale
Spiny Oakworm
Pinkstriped 0akworm
Orangestriped Oakworm
Walnut Caterpillar
Yellownecked Caterpillar
REDBUD CANKER - Botryosphaeria dothidea - The "red flags" in the fence rows and
along the wood’s edge stand out amongst the green foliage background. The " red flags" are the branch or branches of redbud trees killed by this canker disease. The cankers are sunken areas on the branches with the bark still intact over the canker face. Usually the bark does not crack along the callus ridges of the canker. Without the cracking, the cankers are hard to recognize because they blend in with uncankered areas. To identify the canker, look for a sunken area at the base of the dead branches. This disease is common on redbud with symptoms occurring every year. When older, larger trees begin to decline and die, this canker disease is prevalent on the trees. Infected branches should be pruned out to minimize damage especially in ornamental trees. It is best to prune during dry weather and below the canker or cankers.
VERTICILLIUM WILT - Verticillium albo-atrum - Maples primarily sugar and red, may have wilting branches, discolored leaves and branch dieback at this time. Symptoms may occur to one part of the tree crown and progress throughout the crown. The foliage may be sparse and undersized giving the tree crown a thin and transparent look. Some branches may have yellow to red foliage. The fungus produces a black to greenish black stain that can be found on the surface of the sapwood and one to several rings deep in the wood. Remove the bark from freshly wilted branches checking several places because the stain is produced in a narrow streak that could be missed. Finding the stain helps to verify the disease's presence, because other insects (flat headed borers and diseases (Maple Decline) can produce similar symptoms.
Trees may be killed in one season or can survive for several years. Once infected the tree will eventually die. Life can be prolonged if the tree is lightly infected by pruning infected branches and fertilizing in the spring with high nitrogen fertilizers (such as 10-5-5). If you examine the tree and find the stain has moved into the main stem from an infected branch pruning will not help and death may be quick.
NUTRIENT DEFICIENCY SYMPTOMS - The yellow (chlorotic) foliage typical of nutrient deficiency symptoms is present on sweetgum and maples - primarily red maple. You may also begin to observe the symptom on pin oak. The trees will have a yellow appearance and the tissue between the leaf veins will be yellow. The tissue along the main veins will remain green.
Iron deficiency is the cause of the symptom on pin oak and can be related to pH problem in the soil. A high pH will "tie-up" iron making it unavailable to the tree. Iron deficiency may also be the cause of the chlorosis on sweetgum. For red maple manganese or iron may be deficient.
Chelated iron or manganese fertilizers can be applied to alleviate the symptoms. If symptoms are severe on pin oak, the soil pH should be determined because measures may be needed to lower the pH to provide a long term control.
ASH YELLOWS/ASH DECLINE - Mycloplasma-Like Organism - This disease has been observed since the 60's by district foresters and there is one reference to declining ash from a classified forest report, from the late 1940's. It is assumed that the declining ash of the 1940-1980's is the same disease now called Ash Yellows. After years of monitoring the disease in the northern third of Indiana, it may be very common to district foresters and other foresters. In other areas of the state, the disease is not common but may be present. Declining trees will have thin crowns with foliage tufted at the end of branches. Foliage will be slightly off color - not dark green. Branch dieback may be present and can persist for many years. Trees with advanced decline, greater than 50% of the crown with dieback, may have epicormic sprouts in the inner crown and witches brooms may form on the root collar and lower bole. A quick method to determine if Ash Yellows is present is to examine understory saplings and young pole size trees that have died. Witches' brooms readily form on these trees. Witches' brooms are 95% positive that the mycloplasma is present in the tree and woods. Although trees may eventually die, death is a slow process. Trees with greater than 50% crown dieback should be harvested within 5-10 years of reaching this condition. At this time annual radial growth greatly slows or stops Ash yellows commonly occurs on white and green ash but has been found on blue and black ash.
SLUG OAK SAWFLY - Caliroa quercuscoccineae - 
Shingle pin, black and red oak
are-being defoliated by this sawfly. The slug like larvae are a translucent yellow green
with black heads 1/2 to 1 long. They feed in groups on the underside of the leaf. They do
not eat the veins which gives the leaf a lacy translucent appearance. At a distance the
trees will appear yellowish red to reddish brown color. There are two generations per
year. The second generation in August and September produces the most noticeable
defoliation.
FALL WEBWORM - Hyphantria cunea - The second generation webs become evident in southern Indiana during July. The webs are formed at the end of the branches and enclose the leaves for the caterpillars to feed upon. Black walnut, redbud, sycamore, hickory, black cherry, persimmon are common hosts but the webworm will feed on many other species. Localized populations have developed into epidemics in areas across the state in the past. They could do this again. At epidemic levels, entire trees are covered with silk webs. Defoliation usually does not hurt the tree. The web turns black and ugly with age and thus becomes unsightly. Pruning webbed branches and destroying the web is one control . If an insecticide is needed, it should be applied early when the web is small and must penetrate the web. The caterpillars do not leave the web until they pupate. Sevin, malathion, Orthene, Dursban and others can be used.
LACEBUGS - Corythucha spp. - White oaks are beginning to have a dull green appearance with the leaf color on some trees turning a dull red or rust red color. This may be the result of feeding by lacebugs. Lacebugs feed on the underside of the leaf by sucking individual cell contents. This creates a chlorotic stipple on the upper leaf surface. On the under surface, shiny blacks specks indicate the lacebug's presence. The adult lacebugs are 1/4' long with a flat clear lacy wing cover over their body. In addition to white oak, lacebugs will also feed on sycamore, redbud, basswood, elm, hackberry and other species. Control measures are not recommended because feeding occurs late in the growing season.
SPIDER MITE - Oligonychus spp. - The dull green color to oak leaves may also be the result of spider mite feeding. They feed on the underside of the leaf and are not easily seen because of their small size. If you do not see the black specks and adult lacebugs, then the discoloration is probably from spider mites. Spider mites like the hotter part of the summer. They commonly attack spruce trees producing a reddish brown or purplish red color to the inner needles. One way to recognize their presence is the morning dew on the silk threads between the needles or the needle hanging in "mid air" by the silk thread. Besides the oaks and spruce, spider mites will feed on other trees such as scotch pine Christmas trees which were heavily damaged in recent years.
TULIPTREE SCALE - Toumeyella liriodendri - The crawler stage will emerge in late August or early September. For heavily infested ornamental trees, inspect the trees once or twice a week for emergence of the crawler. Crawlers are the size of a pinhead and black in color. Seedlings to 4" DBH trees can be killed by the scale. Heavily infested trees are easy to recognize by the sparse foliage and black appearance from sooty mold growing on the honeydew secreted by the scale. Adult scales are "helmet" shaped l/4-3/8" diameter and orangish to reddish black in color. They are found on the twigs. A summer oil, insecticidal soap, Orthene, malathion, Dursban, or Mavrik can be used for control.
JAPANESE BEETLES - Popillia japonica - 
The green and red metallic beetles
are still feeding on the foliage of trees shrubs and vines. They started feeding in mid
June in southern Indiana and should be finished by mid to late August. The rust red
foliage on grapevine, sassafras, multiflora rose and ornamental fruit trees is the
skeletonizing defoliation of Japanese beetle. They usually feed from the underside of the
leaf preferring the top leaves of seedlings first. Mixed hardwood plantations planted in
old pastures could have moderate to heavy defoliation because the, grass covered field
supported a population of beetles. Another concern in old fields is the root feeding of
Japanese beetle grubs that may cause the gradual death of seedlings.
LOCUST LEAFMINER - Odontata dorsalis - The rust red appearance to black locust from locust leafminer defoliation should be evident in southern Indiana, especially southeastern Indiana. Populations and defoliation from this leafminer have been low for several years. The adult beetle skeletonizes the leaf and the larvae mine between the upper and lower leaf surfaces. The blotches created by the leaf mining produce the rust red color of black locust.
MIMOSA WEBWORM - Mimosa and honeylocust across the state have the brown webs created by the small larvae which feed inside the web for protection. There are two generations, per year and the second generation should be starting around July. The web and defoliation create a tan to reddish brown appearance. In some areas webbing and defoliation is heavy. If control measures are needed on Ornamental trees, B.t., orthene, Sevin, Dursban.,and the Pyrethrins(Mavrik, Asana) can be used.
BAGWORM - Thyridopteryx ephemeraeformis - Many think of bagworm
as a pest of conifer trees such as Arborvitae, E. red cedar, white and scotch pine, and
Norway and blue spruce. However, bagworm will feed on many hardwoods such as oaks, maples,
black locust, sycamore, persimmon, elm and others.
Also, the name "bagworm" is used by many to refer to the tents of Eastern Tent Caterpillar that occur in black cherry at this time of the year. Or they are referring to the webs of Fall Webworm found at the end of branches of various hardwoods - black walnut, persimmon, black cherry, sycamore and other others - in the late summer.
Bagworm is the grayish brown silken case covered with needles or leaves approximately 2" long when fully grown. They firmly attach to the twigs of trees infested. The larva stay inside the bag while feeding, and it is only the male moth who emerges from the bag. The female stays in the bag and lays her eggs in the bag which overwinter.
The cold winter temperatures may have killed eggs in bags that were exposed. Bags inside infested trees may have had enough protection from the cold temperatures for eggs to survive. Egg hatch usually occurs in late May and early June. At this time insecticide treatments are the most effective. Once bags reach 1" in length, it is much harder to achieve control and prevent defoliation. Insecticides available are Dipel, Thuricide, Orthene, Cygon, Diazinon, Dursban or malathion. Another good control is hand removal and destruction of all bags, but this should only be recommended for individual ornamental trees.
White pine has been severely defoliated in previous years and had top dieback of the tree from feeding on the bark of twigs by early instar larvae. Carefully examine white pine for the small bags that will look like buds. Bagworm tends to attack the top whirls of the tree first. So examine this area when surveying for Bagworm.
TWIG GIRDLER - oncideres cingulata cingulata - Persimmon, hickory, pecan and other trees may have twigs falling to the around or hanging broken in the tree. A closer look will reveal a smooth "V" shaped cut encircling the twig. The center of the cut on the fallen twig will have splinters of wood. When the "V" cut nears the pith, the weight of the twig causes it to snap. The smooth cut is made by the adult beetle so that the eggs can be laid in the fallen twig. The fallen or broken twigs are not a serious problem to larger trees, however seedlings and saplings could be seriously damaged. Collecting and burning the fallen twigs helps to minimize the damage.
SUMMER CATERPILLARS - Did you observe defoliation by any of the summer feeding caterpillars? They are usually observed on oak or black walnut. When they defoliate the tree they usually eat all of the leaf except for the main vein and lateral veins. In plantations defoliation usually occurs to a few scattered trees and can be from a few leaves to a large percent of the tree. The defoliation does not seriously hurt the tree. Described below are some of the caterpillars you may, have observed.
Spiny Oakworm - Anisota stigma - 
The
caterpillar is tawny and pinkish in color with white specks. There are two long-curved
spines on the second segment behind the head. Short backward curving spines occur on the
other body segments. They grow to 2" in length.
Pinkstriped 0akworm - Anisota virginiensis - This caterpillar is greenish brown with four pink stripes down its' body, The two long curved spines are on the second segment behind the head like the Spiny Oakworm. The spines on the other body segments are shorter than spines on the spiny oakworm. They grow to 2" in length.
Orangestriped Oakworm - Anisota senatoria - 
Of the summer caterpillars,
this species has caused widespread defoliation to forests. It also grows to 2" in
length, has two spines on the second segment behind the head and has shorter spines on the
remaining body segments. However, it is black in color with 8 orange-yellow stripes down
its' body.
Walnut Caterpillar - Datana integerrima - 
Young
caterpillars are a dark red color. Older caterpillars turn black in color. Fine gray or
white hairs cover the body and white stripes line the body. They feed in groups and raise
their head and tail when disturbed. Besides black walnut, they feed on butternut, hickory
and pecan.
Yellownecked Caterpillar - Datana ministra - 
This is another late
summer feeding caterpillar like the walnut caterpillar. You may see the colonies feeding
on oaks, maples, elm and other species. They have one generation per year and should
complete the larval stage by the end of August. The caterpillar is black with 4 yellow
stripes down its back. The segment behind the head is orange-yellow. The body is covered
with gray hairs. They feed in a colony and will raise their head and tail when disturbed.
The need for control and the control measures are the same as for the walnut caterpillar.
OAK WILT - Ceratocystis fagacearum - Oak wilt has become more
evident on red and black oak in northwestern Indiana. The wilting and dying can be seen in
yard trees and woodlots in several counties. Starting in July, premature defoliation may
have occurred with the fallen leaves a green to bronze green color. 
Gradually the tree continues to die and you may observe other dead trees
adjacent to the dying tree indicating that tile disease has been there for more than one
year and is spreading by root grafts. Sanitation is one measure to use to manage the
disease. Wilting or dead trees can be cut and destroyed. If they are cut and held for
firewood, the firewood pile Should be tightly covered with a tarp to prevent sap beetles
from visiting the logs and then carrying the spores of tile fungus away to infect healthy
trees. For yard trees, the root grafts need to be severed to prevent spread from tree to
tree. This can be done ditch-witch trencher or vibratory plow (like those used to install
underground utility lines). The line to sever root grafts should be at least one live tree
away from the infected tree. In woodlots, use the oak wilt trees as the center of an
opening in the woods.
PINE ROOT COLLAR WEEVIL - Hylobius radicis -The weevil's feeding produces two symptoms - "flagging" of twigs (outer twigs turn reddish brown) from adult weevil feedings in the spring and death of the tree from larval feeding (girdling) below the root collar which can occur throughout the year. Adult weevils chew holes in the bark down to the wood which become covered with white resin and make the twig appear rough textured. They chew individual holes alone the length of the twig which eventually girdle it. Larvae feed under the bark on the stem and larger roots below the soil line. Removal of the soil reveals a black resin soaked appearance to the bark surface and soil around the root collar. After several years of feeding, trees eventually die. The weevil can be managed by using stump treatments of Lindane or Dursban after each harvest. In heavily infested plantations, root collars of live trees can be treated with the above insecticides and Orthene can be applied in August or September to the tree top to kill newly emerging adult weevils. Also, growers should change to shorter rotations in heavily infested fields in an effort to salvage as many trees as possible.
Introduced Pine Sawfly- Diprion Similis- The
sawfly has two generations. The sawfly has two generations and a partial third generation
in southern Indiana. The second generation usually produces the noticeable defoliation,
which means that you may not observe thin defoliated crowns until September and October in
plantations defoliated for the first time. For plantations defoliated this year you will
observe the thin defoliated crowns in April with the level of defoliation increasing
during June to July.
The larvae has a black head, a dark body, black stripes down the back and yellow and black spots on the sides. The first generation larvae will be present from mid-May through June. The second generation is present from late July through September. A third generation may be present in November. When larva are not present and during the winter, you can recognize their presence from the brown capsule-like pupal cases attached to needles and twigs of white pine or to twigs of understory shrubs and weeds.
The sawfly prefers white pine but also feeds on scotch, red, jack and mugho pine. The first generation feeds on older needles but second and third generations feed on current year and older needles. It is the multiple generations and feeding on all needles that can severely defoliate and stress the tree. Damage will be growth loss, increased stress making trees more susceptible to bark beetles and root rot and possible mortality in sawtimber size trees. Management decisions should be made with consideration of the overall management goal for the forest stand, the amount of past defoliation, an estimate of future defoliation level, the stand stocking level, an estimate of the tree and stand's current health (food or poor), and an estimate of damage (growth loss and mortality). For Christmas trees the loss of aesthetic quality from defoliation is the prime consideration when making a management decision. Management tools will include harvesting and thinning in forest stands and pesticides in Christmas tree and windbreak plantings. Pesticides available include Orthene, Sevin, Cygon, malathion and Dursban.