Number 5 - June 2, 2014

Caterpillar Hunter These adult beetles are attracted to lights at night. They may be noticeable due to The large ground beetle Calosoma has their large size and bright colors in the been reported in the Bloomington and evening around lights or in parking lots Joliet areas of the state. This 1.2-inch and other brightly lit areas in the morn- long beetle is broadly oval with long ing. They are considered to be beneficial black legs and antennae. There are spe- insects and should not require control cies with purple wing covers and others measures. They are large and predaceous with bright metallic green wing covers beetles, and they will probably bite if that occur in Illinois. The ones being they are handled. (Phil Nixon) seen currently have green wing covers.

These beetles are commonly known as Black Cutworm fiery searchers or caterpillar hunters. One species, C. sycophanta, was intro- There have been large flights of black duced from Europe into the northeast- cutworm moths into Illinois for several ern United States in the early 1900s to weeks. This insect overwinters in the control gypsy moth caterpillars. Both southern U.S., flying up into the state in the larval and adult stages feed on cat- the spring. There are several generations erpillars, with the adults climbing per year in Illinois. Golf course personnel through trees in search of caterpillars. should be on the lookout for black cut- worm larval infestations in bentgrass, Once introduced, this ground beetle ryegrass, and fescue. They do not cause spread much faster than the gypsy moth damage to Kentucky bluegrass as most and has been known to occur in Illinois larvae are unable to survive on it. for decades. It has been blamed partially for the huge reduction in the number of Damage on greens appears as circles 2 giant silk moths, such as cecropia, pro- to 3 inches in diameter where the grass methia, luna, and Polyphemus moths. blades are eaten down to the crowns. These moths are generally forest insects, Frequently, there is a shallow hole in the so the loss of large forest expanses to center of the circle. Cutworm caterpil- agriculture and other development is lars feed at night, tending to feed in a also a factor. The small remaining forest circle, as far as they can reach, with their remnants likely allow increased preda- posterior end frequently inserted in a tion by birds and parasitic wasps, so the shallow hole. These damaged areas are silk moth decline is probably due to sev- most numerous within 30 or so feet eral factors. from the green apron because the older, larger cutworms like to hide in the taller detergent in a gallon of water. Distribute turf around the green during the day, this evenly over a foot square of turf; a commuting onto the green at night to watering can works well. Within a cou- feed. Feeding damage looks like ball ple of minutes, the irritated larvae come marks where a golf ball skipped across up onto the turf surface. Only two to the green, rubbing off the grass blades. three cutworms per foot square are Thus, golfers do not recognize the dam- enough to result in noticeable injury. An age as being caused by an insect. application of bifenthrin (Onyx, Talstar), carbaryl (Sevin), chlorantroniliprole Additional damage is caused by insect- (Acelepryn), deltamethrin (DeltaGard), feeding birds, such as starlings, robins, spinosad (Conserve), or trichlorfon grackles, cowbirds, and blackbirds. In (Dylox) controls the caterpillars. Insecti- feeding on the younger cutworms that cidal nematodes are also effective. hide in the thatch of the green, they pull up small divots about one-half inch Cutworm moths lay their eggs near the tip across. These little divots are large of grass blades, so frequent mowing and enough to deflect putts, causing golfers clipping removal reduce caterpillar num- to get upset. The sand in these divots bers 75 to 97%. Dump clippings baskets also quickly wears the edge of greens well away from greens and other bent- mowers blades, causing the blades to grass areas. Over 90% of the eggs survive require sharpening and replacing more the mowing process, so dumping the clip- often. Birds feeding on black cutworms pings at the green apron results in cater- can be a hazard at airports. pillars that can easily attack the green. Homeowners who collect grass clippings Damage to lawns is frequently hidden by and use them to mulch around vegetable the taller grass, although lawns may plants and flowers concentrate the eggs have irregular, roundish, brown areas into smaller areas, resulting in heavy feed- where the green grass blades have been ing damage from the resulting larvae to eaten, revealing the thatch. More com- their garden plants. Top-dressing the monly, bird damage is obvious. Because green with sand also reduces the number lawn turf is rooted deeper and more of cutworm larvae. (Phil Nixon) firmly, it is unlikely to be pulled out by the birds as occurs on golf greens. In- stead, round holes about one-half inch in Invasive Species Spotlight: European diameter are punched through the turf Gypsy Moth by the birds' beaks as they search for larvae. Lawns with many cutworms look Throughout the summer, my two in- dingy from a distance due to the brown- terns, Lily and Evan, will be providing ish to blackish holes where the underly- readers with some articles focusing on ing soil shows. invasive species in Illinois. While they will be heavily involved with invasive Black cutworm larvae are dark-colored, species monitoring, they’ll also be gain- heavy-bodied, and up to one-and-one- ing some experience in outreach as well. half inches long. They can be flushed If there is a particular invasive species from the turf with a teaspoon of 5% py- topic you’d like to learn more about, let rethrum or 1 tablespoon of dishwashing us know! First up, gypsy moth! The European gypsy moth (EGM), Modified Growing Degree Days (Base Lymantria dispar, is a non-native moth 50°F, March 1 through May 29) that can attack up to 500 tree and shrub species. It is one of the most destructive Historical One- Two- Station Actual Average Week Week forest pests in the United State. It is also Location Total (11 year) Projection Projection present in the northern part of Illinois. Freeport 558 436 647 762 Larvae can commonly be found on St. Charles 450 414 532 638 hardwood trees such as oak and aspen. DeKalb 466 479 561 680 Monmouth 560 533 659 783 EGM attacks trees by feeding on their Peoria 595 569 697 825 leaves. If defoliation is heavy and re- Champaign 625 583 733 866 peated, trees may die after 2 years of Springfield 742 651 857 996 infestation. Tree mortality may also be Brownstown 735 711 856 1000 Belleville 778 744 901 1040 increased when trees regrow a new set Rend Lake 829 803 960 1112 of leaves. This is energetically costly to Carbondale 827 760 952 1096 the tree which may make it susceptible Dixon 846 818 976 1124 Springs to other pests.

EGM caterpillars are voracious leaf eat- Insect development is temperature de- ers. These caterpillars consume as much pendent. We can use degree days to help leaf tissue as they can, as quickly as they predict insect emergence and activity. can, in order to nourish themselves and Home, Yard, and Garden readers can use become reproducing adults. A single the links below with the degree day ac- caterpillar can consume 11 square feet cumulations above to determine what of vegetation during its lifetime. insect pests could be active in their area.

Female EGM lay their eggs in summer on GDD of Landscape Pests any flat surfaces such as patio furniture, GDD of Conifer Pests auto tires, fire wood, grills, and children’s toys. When these objects are transported, Degree day accumulations calculated the egg masses are moved with them. using the Illinois IPM Degree-Day Calcu- lator (a project by the University of Illi- Caterpillars are most active in May and nois Department of Crop Sciences and June when they are feeding on leaves. the Illinois Water Survey). (Kelly Estes) Full grown gypsy moth caterpillars are about 2-3 inches long. They are a grayish color with long hairs throughout their bodies. Caterpillars have five pairs of Giant Confusion: Giant Hogweed and blue spots and six pairs of red spots Common Look-Alikes along their backs. Giant Hogweed (Heracleum mantegazzi- Around mid-summer, caterpillars go into anum) is an invasive plant from Asia and the pupal stage of their life cycle. After 2 was likely introduced into the United weeks adult moths emerge from the co- States due to its use as a spice in foreign coon. Cocoons vary in size according to dishes. This exotic, invasive has been their sex. (Lilly Calderon, Kelly Estes) identified in a couple of Illinois counties.

This plant can grow to heights of 10 to 15 Anthracnose on Shade Trees: ft and a width of 5 ft. It is a biennial or A Review of the Tolerable, the Bad, short lived perennial that has a mostly and the Ugly green hollow stem with reddish purple raised spots along with coarse short hairs Anthracnose samples are just beginning on the stalk. The stem can grow to 2 to 4 to show up at the Clinic this season. inches in diameter. The plant has small Conditions have been favorable this white flowers in flat umbels that bloom in spring for the development of anthrac- mid-May through July. The seeds are el- nose on shade trees. Anthracnose is the liptical shaped and one plant can produce disease name designated for a group of up to 20,000 seeds. After seeding, the closely related pathogens which cause a plant dies back to the taproot which can variety of symptoms including leaf live throughout the winter. blight and deformation and cankers on stems and branches, though symptoms In addition to being an invasive weed that that develop depend on the tree that is can quickly overtake an area by crowding infected. The occurrence of anthracnose out other plants, giant Hogweed is also on shade trees is favored by cool, wet harmful to humans by creating a clear wa- springs. Anthracnose diseases can be tery sap that can cause burning and blis- hosted by a number of shade trees in- tering on the skin when combined with cluding sycamore, ash, and maple. sunlight and can also cause blindness. This sap can get onto someone just by This disease is very noticeable on syca- brushing by the leaves or breaking the mores, you can observe what appears to stem or leaves. It is highly recommended be delayed leafing on the tree and leaves that when dealing with this plant one and growing tips dying as they emerge. should wear gloves and protective cloth- Upon closer examination of twigs you ing to allow no contact with skin. can find cankers which are sunken, dead looking areas. Cankers on twigs can re- Giant Hogweed belongs in the carrot or strict water and nutrient movement to parsley family (Apiaceae). It has several leaves, resulting in leaf and twig die- look-a-likes including cow parsnip (Hera- back, while cankers on larger branches cleum lanatum), angelica (Angelica atro- can girdle and kill entire branches. The purpurea), and poison hemlock (Conium small black fruiting bodies of anthrac- maculatum) - all common plants in Illinois nose which have a “pimple” like appear- and all commonly mistaken for giant ance (but black) can also be found on hogweed. Although many of these plants twigs and branches. Another symptom may look like giant hogweed at first you may observe is witches brooming glance, none of them get to be as large or around terminal shoots that were killed have its exaggerated characteristics. by the anthracnose infection.

Giant hogweed is still rare in Illinois. Anthracnose also can develop on ash While visitors in natural areas are un- trees. The symptoms you would ob- likely to encounter this plant, it never serve if your ash has anthracnose are hurts to keep a watchful eye for this and dark blotches along the margins of other invasive plants. (Evan Cropek, leaves which in turn cause distorted Kelly Estes) leaves, and small purplish-brown spots located near the leaf centers. The most vigor. Concentrate on boosting tree vi- significant symptom is leaf drop, when tality to promote new growth. Prune in new green leaves fall from the tree. and around the tree to open it to better Though this disease is not known to air movement. Remove dead or dying cause significant stress to ash trees in a branches, water in periods of drought, single year, 3 or more consecutive years and mark calendars now to fertilize af- of heavy defoliation (more than 25% de- fected trees in the fall. Watering in foliated) of ash trees can leave them summer drought is probably the best more susceptible to other diseases. advice we can give to help infected trees.

Symptoms of anthracnose disease on Unless anthracnose fungi have repeated- maple are similar to those of ash: pur- ly hit a tree or a very young tree is in- plish brown blotching along leaf veins volved, we do not recommend using that can span out to the leaf margin. fungicides. However, if the problem is That being said, anthracnose is usually severe enough, fungicide sprays can be not a severe disease on maples. It is applied to trees in the early spring when more known for detracting from the aes- buds begin to swell, and should be ap- thetic beauty of maples by the discolora- plied every 7-14 days when it is a rainy, tion of the leaves, usually no significant wet spring as these are conditions most defoliation ever occurs. favored by development of anthracnose. Fungicides that will help control an- Cultural methods to help control this thracnose in shade trees include chloro- disease include maintaining proper sani- thalonil, thiophante-methyl, mancozeb, tation of leaves and pruning off and propiconazole, and copper fungicides. burning (or remove from site) twigs and branches with cankers. Fertilizer can be For more information, see Report on applied in late fall one month before the Plant Diseases, no. 621 (Adobe PDF). first frost or in early spring one month (Chelsea Harbach and Suzanne before last frost to help increase tree Bissonnette)