EENY-653 Bluegrass Billbug Sphenophorus parvulus Gyllenhal (Insecta: Coleoptera: Curculionidae: Dryophthorinae)1 Luis F. Aristizábal and Eileen Buss2 Introduction Synonymy The bluegrass billbug, Sphenophorus parvulus Gyllenhal, Calendra parvula Gyllenhal 1838 (Vaurie 1954) is a weevil that commonly infests cool season turfgrasses, especially Kentucky bluegrass, Poa pratensis L. (Figure 1). Calandra parvulus Gyllenhal 1838 (Schellenberg and More than 64 Sphenophorus species occur in the United Clairville 1789 cited by Kuhn et al. 2013) States. Florida contains about 25 of them, including Sphe- nophorus apicalis LeConte, Sphenophorus cariosus Oliver, Sphenophorus parvulus Gyllenhal 1838 (Vaurie 1951; ICZN Sphenoplwrus inaequalis Say, Sphenoplwrus mininms Hart, 1959) and the hunting billbug. Sphenoplwrus venatus vestitus Chittenden (Peck and Thomas 1998; Woodruff 2001; Huang and Buss 2009). Larval and adult billbugs can be damaging in residential lawns, golf courses, or orchard grasses. Figure 2. Distribution of bluegrass billbug, Sphenophorus parvulus Gyllenhal, in the United States. Red stars show the states where Figure 1. Adult bluegrass billbug, Sphenophorus parvulus Gyllenhal, Sphenophorus parvulus had been reported. walking on turfgrass. Credits: Map modified from General Turf and Insects - Stem and Credits: David J. Shetlar, Ohio State University Thatch Pests by David J. Shetlar, Ohio State University. 1. This document is EENY-653, one of a series of the Entomology and Nematology Department, UF/IFAS Extension. Original publication date April 2016. Reviewed February 2019. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication. 2. Luis F. Aristizábal; and Eileen Buss, associate professor emeritus, Department of Entomology and Nematology; UF/IFAS Extension, Gainesville, FL 32611 The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office. U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension. Distribution and legs are wrapped around the middle of the body. Pupae range from 5.5 to 10 mm in length (Satterthwait 1931a). Splzenophorus parvulus is widely distributed within the United States and Canada (Vaurie 1951; Johnson-Cicalese et al. 1990; Watschke et al. 1995). Vaurie (1951) reported the distribution of Sphenophorus parvulus to include Ar- kansas, Colorado, Florida, Georgia, Illinois, Iowa, Kansas, Kentucky, Minnesota, Missouri, New York, and Texas, and also in Ontario, Canada. It has also been reported from Utah and Washington (Tashiro and Personius 1970), and in Nebraska (Kindler and Spomer 1986; Bruner 1890) (Figure 2). Description Sphenoplwrus parvulus eggs are bean-shaped (oblong), and are off-white or cream-colored (Figure 3). Eggs are 1.4 to 1.6 mm long and 0.6 mm wide (Kindler and Spomer 1986). Figure 4. Larva of the bluegrass bill bug, Sphenophorus panvulus Gyllenhal. Credits: David J. Shetlar, Ohio State University Figure 3. Egg of the bluegrass billbug, Sphenophorus parvulus Gyllenhal. Credits: David J. Shetlar, Ohio State Univeristy Larvae are soft bodied, legless, off-white in color, and have a distinctly sclerotized (hardened) head capsule (Watschke et al. 1995). The head capsule color varies from yellowish after hatching to dark red or brown when older (Figure 4). Larvae range from 1.2 mm (first instar) to 8 mm in length Figure 5. Pupa of the bluegrass billbug, Sphenophorus panvulus (fifth instar). The fifth instar becomes a pre-pupa, and Gyllenhal. actively constructs an earthen cell in which to pupate. Credits: David J. Shetlar, Ohio State University Pupae (Figure 5) are soft and initially off-white in color Adult Sphenophorus parvulus (Figure 1) are distinguished and then turn rusty brown just before the adult emerges. by their typical snouts and for their brown-black color The pupa has the distinctive snout visible, but the wings with uniformly small pits in the pronotum. Teneral (newly Bluegrass Billbug Sphenophorus parvulus Gyllenhal (Insecta: Coleoptera: Curculionidae: Dryophthorinae) 2 emerged) adults look rusty brown in color but darken when Larvae begin feeding inside grass stems immediately after sclerotized. Adult body lengths range from 5 to 8 mm; hatching, producing powdery frass that is visible if the mean length is 7.6 mm for females and 6.9 mm for males. stems are cut. Large larvae (third instar) exit from the grass The elytra (wing covers) are characterized by punctate fur- stem to the soil where they feed on roots and rhizomes rows forming striated lines similar to parallel chains (Vaurie (Kindler and Spomer 1986). Larval development ranges 1951; Watschke et al. 1995). The antennae are geniculate from 23 to 60 days, depending on temperature (Vaurie (elbowed) and arise from the base of the snout. 1951; Watschke et al. 1995). Pupae are found in the soil close to the host plant, 2 to 5 cm below the surface. The Life Cycle and Biology pupal period ranges from eight to ten days (Satterthwait 1931). Finally, a new generation of adults emerges and the Sphenophorus parvulus has one to two generations per year life cycle repeats. in Kentucky, Ohio, West Virginia, and Pennsylvania, but has two or more generations in warmer regions (Figure 6) (Kindler and Spomer 1986). The life cycle of Sphenophorus Hosts parvulus may be more synchronized in the northern US Sphenophorus parvulus has become a serious pest of than in the South due to consistent seasonal changes. The Kentucky bluegrass, Poa pratensis L., and Zea mays L. following life cycle is based on studies in Nebraska (Kindler This insect also attacks other grasses including perennial and Spomer 1986). Sphenophorus parvulus adults begin ryegrass, Lolium perenne L.; tall fescue, Festuca anmdinacea emerging from their overwintering sites (beneath dead Schreb; barley, Hordeum vulgare L.; wheat, Triticum leaves, under rocks, sticks, and litter, for example) in the aestivum L; rye, Secale cereal L.; Virginia orchardgrass, spring when the soil temperature (2.5 cm deep) reaches 18 Dactylis glomerata L.; and bentgrass, Agritis spp. (Tashiro to 20°C. and Personius 1970; Johnson-Cicalese 1990). Economic Importance According to Haydu et al. (2008), the economic value of the turfgrass and lawncare industries in the United States are significant. In Florida, for example, turfgrass is part of the residential, commercial, and recreational landscape includ- ing golf courses. Therefore, any damage caused by pests Figure 6. All developmental stages of the bluegrass billbug, in turfgrass, lawns, and golf courses will have a negative Sphenophorus parvulus Gyllenhal. economic impact. Credits: David J. Shetlar, Ohio State University High populations of Sphenophorus parvulus can kill large After emergence, adults search for host plants and start areas of grass. Residential home lawns, commercial sod feeding. From late April through May, mated females chew fields, and golf courses planted with susceptible turfgrass holes in the base of grass stems into which they insert species are affected by this insect pest. Lawns can provide one to three eggs. Each female lays about 255 eggs over a benefits to the landscape, environment, and homeowners. three month period, but most egg laying occurs in the first Benefits of lawns include increasing aesthetics look that month. Eggs can be found from May to September with increases the economic value of landscape, improvements a peak oviposition period in May and June in Nebraska of recreational areas, but also results in reduction of pol- (Kindler and Spomer 1986). At 21°C the incubation period lution and prevention of soil erosion. Direct and indirect for eggs ranges from six to 11 days. damage caused by Sphenophorus parvulus on lawns and golf First generation larvae finish development by the end of courses sometimes necessitate control treatments and lawn June and new adults begin to appear in July. These adults replacement, which affect the economy of homeowners and often lay eggs that can produce second generation adults in golf courses. August until early October. Only Sphenophorus parvulus adults can overwinter, in contrast to the hunting bill bug. Damage Sphenophorus venatus vestitus, which can have multiple life Both Sphenophorus parvulus adults and larvae feed on or stages overwinter or even remain actively feeding. in grass stems, causing serious damage. The severity of damage depends on the size of the insect population and the overall health of the infested plants. Bluegrass Billbug Sphenophorus parvulus Gyllenhal (Insecta: Coleoptera: Curculionidae: Dryophthorinae) 3 Larval stem boring and root feeding reduce or prevent the applied after other control tools have been used, if the movement of nutrients in the grass and can cause plant insect population has increased. death (Vaurie 1951). In Kentucky bluegrass, association between the number of larvae and live stems was correlated Monitoring: Monitoring is the first strategy to detect (Kindler