Sod Webworms and Armyworms - Sod Solutions

Sod Webworms and ArmywormsTurfgrass Insider—Late SummerB IG F L U S H OF W O R M S IN L A W N S AS WE G E T R E A D Y F O R F A L LI am seeing a another round of problems with tropical sod webworms (Herpetogramma spp.) in St.Augustinegrass, centipedegrass, and carpetgrass lawns here in September. Tropical sod webworms are one ofthe most destructive pests of St. Augustinegrass and carpetgrass. We are seeing them now in centipedegrass,bermudagrass, and zoysiagrass lawns as well.Sod Webworm Facts Moths lay eggs in tall grass andshrubs and rest in landscapes duringthe dayTropical sod webworm (http://turfgrass.com/pics/pics39.html)Eggs hatch in a week—larvae toadult in approximately 25 daysDamage may begin near flowerbedsLook for notched leaves & greenexcrement pelletsWebworms feed mainly at night andare lethargic compared toarmywormsWatch for feeding birdsSt. Aug and carpetgrass are favoritesHow do you know if it is tropical sod webworm damage?The lawns may have a few chewed up circular areas or browned out areas that exceed a 1000 ft 2 . First glance,you will think disease. After close inspection of the turf, you will see that the leaves have heavy chewing damageand you may see green excrement pellets.. Young webworm larvae feed along the mid-rib trough of the leaf.Mid-sized larvae chew notches in the edges of leaves and older larvae will completely strip off the leaves similarto the damage caused by armyworms. It is the notched edges on grass blades that are the tipoff. Additionally, theworms leave trails of a silky web as they crawl through the grass. You can spot these “webs” in the morningwhen dew is on the ground. Like armyworms, watch for birds feeding in the area.

Tropical sod webworm damage in 2010 in St. Augustinegrass lawns in Vermillion Parish and Baton RougeTropical Sod Webworm Life CycleMoths are 0.5 to 0.75 inches long and have snout like projections on their heads. You see the moths flutteringover the turf and in flowerbeds areas nearby. This short-lived moth does not feed on the turf but isresponsible for laying the eggs in the grass and landscapes. The eggs hatch in 7 to 10 days and the larvaebegin feeding on the turf. The larvae (worms) can get up to 1 inch long and are light green to graygreen with dark spots on their body. There is no characteristic inverted Y shape on the head of webwormslike you see with armyworms. The tropical sod webworm completes their development from egg to mothemergence in 5 to 6 weeks. The species overwinters as larvae in the soil. We could get 3 to 4 generationsin a season.Tropical sod webworm mothMature tropical sod webwormMature tropical sod webworm

POPULATIONS OF FALL ARMYWORMS ARE BEING REPORTED ALL OVER THE STATEFall armyworms (Spodoptera frugiperda). I am getting many reports of exploding armyworm populationsand turf managers seeing flocks of birds in sports fields and home lawns. Armyworms will feed onanything including weeds but bermudagrass is most vulnerable to attacks. Scout your lawns, fields, andfairways.Look for the inverted Y on the armyworm’sFall Armyworm Life CycleFall Armyworm FactsMoths lay egg masses on light coloredobjects in turf areas (goalpost, flags etc.)Eggs hatch in a 2 to 3 days—larvaemature in as little as 12 daysUsually attack with very heavy populations—damageresemblesdrought from a distanceArmyworms active at mid-dayWatch for feeding birdsBermudagrass and ryegrass arefavorites3 to 4 generations possibleThe adult moth responsible for the armyworm is brown in color with a wingspan of 1 ½ inches wide. Theeggs are laid on the leaves of the turfgrass in clusters but it is not unusual to see egg clusters on light coloredobjects near turf areas such as goal posts or fences. The eggs may hatch in as little as 2 days. Thelarvae can feed for 2 to 3 weeks causing severe turfgrass damage. Armyworms have chewing mouthparts that completely devour the leaves rendering large areas void of foliage. Eventually, the larvae burrowinto the soil and pupate transforming into the adult moth. The process takes approximately 2 weeks.Fall armyworm larvae are 1 ½ inches long and black striped their entire body length. They may be black incolor to green. However, the most distinguishing characteristic is the inverted Y on its head.Fall armyworm life cycleIdentifying characteristicsFall armyworm moth

Diagnosing the problem with soapy water...Armyworms feed at midday but sod webworms prefer to feed at night.I have found that just looking carefully through the grass during middaymay not turn up any webworms or you just might have a light infestationof armyworms. However, if you make up a soapy solution in a couple ofgallons of water and pour it in a transition area (damaged turf transitioningto good turf), the armyworms present in the area willgo crazy. Tropical sod webworms will at least start moving, making themeasier to spot. You might as well start carrying dishwashing soap and abucket in your truck.Control Options For Tropical Sod Webworms and Fall ArmywormsI have seen tropical sod webworms and armyworms in the same turf before. The good news is that insecticidesthat kill sod webworms work well on armyworms too. The following table gives you some optionsfor controlling worms in turfgrass.Insecticides for homeownersbifenthrincarbarylchlorantraniliproledinotefuranspinosadtrichlorfonCommon Trade Name(s)Talstar, Quali-Pro, etc.Sevin, Carbaryl etc.AceleprynZylam (only sod webworm listed on label)ConserveDyloxWhat can you do about turf recovery?It is too late to apply fertilizers now that we are in September unless we are talking bermudagrass. In mostcases, turf will grow back before the first frost. However, I have seen weak St. Augustinegrass not recoverfrom tropical sod webworm damage before and newly emerging seeded bermudagrasses can be seriouslydamaged.As long as you keep turf areas inspected, you can head off any severe damage with a good insecticide.Birds can be a good indicator but sometimes they get on a population late. Feel free to send any of thisinfo out to your clientele.Ron Strahan