Thyridopteryx Ephemeraeformis Research Articles

Host range, damage extent and leaf consumptions by the bagworm, Thyridopteryx ephemeraeformis Haw. (Lepidoptera: Psychidae) in Bangladesh

Bagworm, Thyridopteryx ephemeraeformis Haw. (Lepidoptera: Psychidae) is a polyphagous pest in Northern America and southern Australia, causing severe damage to several host plants. A study was conducted to record the host plants, damage extent, and morphometrics of bagworms in Patuakhali Science and Technology University (PSTU) from 2015 to 2018. Results revealed a limited number of host plants for bagworm namely guava (Psidium guajava), arborvitae/juniper (Thuja standishii), rangan or jungles, geranium (Ixora grandiflora/Ixora coccinea), mussaenda (Mussaenda philippica), cropperleaf (Acalypha wilkesiana ‘Ceylon), henna (Lawsonia inermis), mango (Mangifera indica), pomegranate (Punica granatum) and betel nut (Areca catechu). The length of tiny larvae, fully-grown larvae, pupa, adult winged male moths, and wingless adult maggot-like females was 1.02 mm, 24.8 mm, 14 mm, 15 mm, and 48 mm, respectively. The average length of the bag was 24.7 mm with a range of 21-28 mm, and the average breadth in the middle of the bag was 6.9 mm with a range of 6-8 mm. The highest number of larval cases per branch was found in guava (56), and the lowest was in copperleaf (8). The highest percent of leaf damage (86.23%) per plant was also observed in the guava plant, and the lowest percent of leaf damage (37.46%) was in copperleaf. The highest number of infested leaves and bags per leaf was observed in the lower stratum of the guava branch, while the lowest infestation was in the top stratum. The highest percentage of leaf area (30%) damage was recorded 72 hours after release (HAR), and the lowest percentage of leaf area (10%) damage was at 24 HAR in guava. The maximum amount of leaf was consumed by bagworm larva at 72 HAR and the minimum amount was consumed at 24 HAR in guava. The maximum leaf area (13.46 cm2) consumption was recorded at 72 HAR, while the minimum amount (3.42 cm2) was consumed at 24 HAR. No significant damage by T. ephemeraeformis was observed in the case of mango, pomegranate, and betel nut plants. J. Asiat. Soc. Bangladesh, Sci. 48(1-2): 1-17, June-December 2022

A report on positive phototaxis exhibited by newly emerged bagworm caterpillars (Lepidoptera: Psychidae)

The bagworm, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae) is a polyphagous moth that defoliates ornamental shrubs and trees. It has been reported as an emerging pest in the coastal agroecosystem of Odisha, India. A small experiment demonstrated that bagworm's newly emerged larva (NEL) was positively phototactic under white and UV light. After emerging in the rearing box, the larva was exposed to 3 volts of LED white and UV lights. After which, its phototactic behaviour was observed. Considering this report, light traps can be used to catch this nuisance species, which may now be more manageable. Hanging light sources on infested plant branches may be one technique, and when larvae congregate on that area of the branch, it may be easy to remove and kill them.

Do Cultivars of Native Plants Support Insect Herbivores?

Native plants are becoming widely used in built landscapes to help mitigate the loss of biodiversity caused by urbanization. The primary advantage of native plant species over introduced ornamentals is their ability to support the development of the insects that fuel vertebrate food webs as well as specialist pollinators. The horticultural industry has introduced many cultivars of native plants to improve their aesthetic value and disease resistance, but there has been little work that measures the impact of these genetic changes on insect herbivores and pollinators. Here we measure how six desirable traits in native woody plant cultivars (leaf color, variegation, fall color, habit, disease resistance, and fruit size) compare with their wild types in terms of their ability to support insect herbivore development, abundance, and species richness. Using a common garden experiment, we quantified the abundance and diversity of insect herbivores using each species and its cultivars for growth and development over a 2-year period, as well as cumulative feed damage over the entire season. We also conducted feeding tests with evergreen bagworm (Thyridopteryx ephemeraeformis) to measure the preference of hatchling caterpillars for cultivars vs. straight species. We found that cultivars that had leaves altered from green to red, blue, or purple deterred insect feeding in all three experiments, a preference for variegated cultivars in one of our three experiments, but no consistent pattern of use among the species and cultivars chosen for other traits. These results suggest that the usefulness of native cultivars in restoring insect-driven food webs depends on the cultivar trait that has been selected.

How climate extremes—not means—define a species' geographic range boundary via a demographic tipping point

Species' geographic range limits interest biologists and resource managers alike; however, scientists lack strong mechanistic understanding of the factors that set geographic range limits in the field, especially for animals. There exists a clear need for detailed case studies that link mechanisms to spatial dynamics and boundaries because such mechanisms allow us to predict whether climate change is likely to change a species' geographic range and, if so, how abundance in marginal populations compares to the core.The bagwormThyridopteryx ephemeraeformis(Lepidoptera: Psychidae) is a major native pest of cedars, arborvitae, junipers, and other landscape trees throughout much of North America. Across dozens of bagworm populations spread over six degrees of latitude in the American Midwest we find latitudinal declines in fecundity and egg and pupal survivorship as one proceeds toward the northern range boundary. A spatial gradient of bagworm reproductive success emerges, which is associated with a progressive decline in local abundance and an increase in the risk of local population extinction near the species' geographic range boundary.We developed a mathematical model, completely constrained by empirically estimated parameters, to explore the relative roles of reproductive asynchrony and stage‐specific survivorship in generating the range limit for this species. We find that overwinter egg mortality is the biggest constraint on bagworm persistence beyond their northern range limit. Overwinter egg mortality is directly related to winter temperatures that fall below the bagworm eggs' physiological limit. This threshold, in conjunction with latitudinal declines in fecundity and pupal survivorship, creates a nonlinear response to climate extremes that sets the geographic boundary and provides a path for predicting northward range expansion under altered climate conditions. Our mechanistic modeling approach demonstrates how species' sensitivity to climate extremes can create population tipping points not reflected in demographic responses to climate means, a distinction that is critical to successful ecological forecasting.

Spatio‐temporal variation in mating success of female bagworms

AbstractThe study investigated spatio‐temporal variation in the mating success of female bagworms, Thyridopteryx ephemeraeformis Haworth (Lepidoptera: Psychidae), across a broad latitudinal range in Indiana, USA, between 2007 and 2009. A series of interconnected equations based on estimates of demographic parameters at different intervals was used to derive the punctual sex ratio and female mating success early and late in the season. Both the mating success of females and the relative abundance of bagworms declined with latitude, which provides indirect support to the mate encounter Allee hypothesis. However, the late emergence of females at northern locations combined with the consistently low mating success of late‐emerging females suggests that the impact of latitude on mating probability is indirectly mediated by emergence time. A variable level of protandry was observed each year, and the low ratio of males per female late in the season was associated with low female mating success. The reduced level of activity of males at temperatures below 18 °C may also account for the low mating probability of late‐emerging females. The weak, inconsistent effect of local variation in sex ratio on female mating success suggests that males commonly disperse from their natal patch, a behavior that may have evolved to reduce inbreeding in local populations of bagworms. Altogether, these results suggest that temporal variation in sex ratio has a greater impact on the mating success of female bagworms than spatial variation in sex ratio.

Broad-scale latitudinal variation in female reproductive success contributes to the maintenance of a geographic range boundary in bagworms (Lepidoptera: Psychidae).

BackgroundGeographic range limits and the factors structuring them are of great interest to biologists, in part because of concerns about how global change may shift range boundaries. However, scientists lack strong mechanistic understanding of the factors that set geographic range limits in empirical systems, especially in animals.Methodology/Principal FindingsAcross dozens of populations spread over six degrees of latitude in the American Midwest, female mating success of the evergreen bagworm Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae) declines from ∼100% to ∼0% near the edge of the species range. When coupled with additional latitudinal declines in fecundity and in egg and pupal survivorship, a spatial gradient of bagworm reproductive success emerges. This gradient is associated with a progressive decline in local abundance and an increased risk of local population extinction, up to a latitudinal threshold where extremely low female fitness meshes spatially with the species' geographic range boundary.Conclusions/SignificanceThe reduction in fitness of female bagworms near the geographic range limit, which concords with the abundant centre hypothesis from biogeography, provides a concrete, empirical example of how an Allee effect (increased pre-reproductive mortality of females in sparsely populated areas) may interact with other demographic factors to induce a geographic range limit.

Dispersal and development of bagworm larvae (Lepidoptera: Psychidae) on three host plants

AbstractThe present study investigated the development and dispersal of bagworm larvae, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae), on three hosts: arborvitae, Thuja occidentalis, blue spruce, Picea pungens, and juniper, Juniperus virginiana. The biomass of larvae was recorded at repeated intervals at 21 field sites. The relative quality of plants varied during larval development: early in the season, larvae were heavier on juniper and arborvitae than on blue spruce; late in the season, in contrast, larvae and pupae were lighter on juniper than on the two other plants. Larvae on blue spruce pupated later than those on arborvitae. In the laboratory, feeding rate and larval growth were not influenced by the density of larvae on the foliage of arborvitae up to a range which greatly exceeded that observed at any of our experimental sites. The incidence of dispersal among neonates emerging on arborvitae was high, as indicated by the high number of larvae captured on sticky traps, and the relatively low number of early instars on arborvitae foliage in relation to the reproductive output of females in the parental generation. The high rate of dispersal among early instars may be due to potential resource depletion over successive generations of bagworms.

Can alien plants support generalist insect herbivores?

Simple rearing experiments were con- ducted to address two questions relevant to under- standing how generalist lepidopteran herbivores interact with alien plants. Yellow-striped armyworm (Spodoptera ornithogalli), luna moth (Actias luna), bagworm (Thyridopteryx ephemeraeformis) and white-marked tussock moth (Orgyia leucostigma) were reared from egg to 5th instar on excised foliage in the laboratory to determine the degree to which highly polyphagous lepidopteran herbivores are physiologically capable of surviving and developing on the suite of alien plants naturalized in the mid- Atlantic. Actias luna larvae from a single population were similarly reared on a representative of each of the 25 native plant genera recorded as hosts for this species to compare the diet breadth of a local population with that listed over the entire geographic range of the species. With few exceptions, all four generalists either quickly starved or grew at an unsustainably low rate on alien foliage. Actias luna larvae survived for 18 days on only 44% of the native plants recorded as hosts over the entire range of this insect and thrived on only 7%. The data suggest that (1) alien plants are unlikely to produce as much generalist insect biomass as the native plants they replace and (2) Lepidoptera that qualify as generalists when host breadth is considered over their entire geographic range may express a far more specialized diet within local populations. Both of these conclu- sions support the hypothesis that alien plant invasions may seriously disrupt terrestrial food webs by reducing the insect biomass required by insectivores in higher trophic levels.

Fitness consequence of pupation site for bagworms (Lepidoptera: Psychidae) on arborvitae

The present study investigated the fitness consequence of pupation site of bagworms, Thyridopteryx ephemeraeformis, on arborvitae. The abundance and survival of pupae were higher on trees with a southern exposure than on those with a northern exposure. Neither sex-ratio nor female mating success was influenced by the exposure of trees. The ratio of females per male, survival of pupae, and mating success of females all increased from the bottom to the top of arborvitae. Our results suggest that bagworm larvae may enhance their fitness by pupating in locations most suitable for pupal survival and female mating success. Because adult female bagworms can not disperse, pupation by female larvae may further influence the performance of their larval progeny, either by favouring the long-range dispersal of ballooning larvae or by providing neonates with suitable foliage nearby their site of emergence.

Influence of Oviposition Experience on Multiparasitism by <I>Pimpla disparis</I> Vierick and <I>Itoplectis conquisitor</I> Say (Hymenoptera: Ichneumonidae)

We evaluated the potential for competition between the exotic ichneumonid parasitoid Pimpla disparis Vierick and the native ichneumonid Itoplectis conquisitor Say, in the form of multiparasitism and destructive host feeding, by examining how previous oviposition experience influenced host selection. Both species commonly attack the host species, bagworm, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae), in central Illinois. We used in our study adult female parasitoids that were naïve, had previously oviposited into hosts that contained heterospecifics, or had oviposited into hosts that initially were unparasitized. Naïve parasitoids of both species were disinclined to oviposit into hosts that already were parasitized by heterospecific larvae, suggesting that female parasitoids could detect the larvae. However, parasitoids with prior oviposition experience were less selective and oviposited into hosts that already were parasitized and unparasitized hosts. Female P. disparis and I. conquisitor probed parasitized hosts more frequently than unparasitized hosts. Adult female parasitoids of both species rarely directly fed on hosts, but those that did preferred to feed on hosts that already were parasitized. For both parasitoid species, the first larva to colonize a multiparasitized host was the most likely to survive to adulthood.

Polyphagy, flightlessness, and reproductive output of females: a case study with bagworms (Lepidoptera: Psychidae)

Abstract 1. We evaluated the relation between plant‐mediated larval traits and the fitness of female bagworms, Thyridopteryx ephemeraeformis Haworth (Lepidoptera: Psychidae) by sampling 29 populations of bagworms on five plant genera (Thuja, Pinus, Picea, Juniperus, and Gleditsia).2. Compared with those on other genera of plants, female larvae on Thuja attained a larger size at pupation and developed faster. The superior quality of Thuja as a larval food plant resulted in a higher potential fitness of females, as indicated by a low level of pupal mortality and high fecundity.3. The fecundity of females increased with pupal size on different plant genera, and the effect of host plant genus was negligible compared with pupal size.4. The mating success of females varied among different populations (0–37% unmated females), but neither host plant, emergence time, nor the size of females had a significant influence on the proportion of mated females.5. The conversion of adult biomass into reproductive tissue, measured as the ratio between the biomass of eggs divided by the biomass of calling females, increased with the pupal size of females and approached 90% for large females. The high rate of egg conversion in bagworms may be related to the neoteny of short‐lived females that invest little in somatic tissue.

Elements of Population Dynamics of Bagworm (Lepidoptera: Psychidae) on Hedge Rows of White Pine

Spatiotemporal elements related to the population dynamics of bagworms, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae), on white pine, Pinus strobus (L.), were investigated by sampling populations of bagworms repeatedly at 12 sites within a 50-km radius in central Indiana. The number of live bagworms declined over time by up to 95% in some sites, and the rate of population decline increased with the initial density of larvae. A comparison of population density of bagworms in past generations with that of the current-year generation revealed that sites heavily infested with bagworms from previous years carried a high number of live larvae early but not late in the season. The positive relationship between densities of bagworms in past and current generations observed at five of 12 sites suggests that larvae commonly do not disperse when they emerge on a suitable host. However, there was considerable variation relative to this pattern, suggesting that dispersal is common as well. Pupation and emergence of adults occurred in late summer and early fall, with some level of phenological asynchrony observed at different sites. Dates corresponding to 50% pupation or adult emergence varied by up to 12 d at different sites. Males suffered higher mortality than females during the pupal stage. The positive correlation between the mortality level of female pupae and previous years' population density may be related to a buildup of populations of natural enemies in sites that were previously heavily infested with bagworms.

Efficacy and Costs Associated with the Manual Removal of Bagworms, Thyridopteryx ephemeraeformis, from Leyland Cypress

Abstract Bagworms (Thyridopteryx ephemeraeformis) are a common pest of landscape plants. The efficacy and costs were determined for the manual removal (handpicking) of bagworms from a single Leyland cypress (X Cupressocyparis leylandii) and estimated for a planting of 40 trees. Manual removal costs were compared to the estimated costs of spraying trees with the insect growth regulator tebufenozide. Handpicking the bags provided 92% control and required 160 minutes for one tree and an estimated 6,400 minutes for 40 trees. Labor costs for manual removal were estimated at $44 for one tree and $1764 for 40 trees. Estimated time required to spray a single tree was 71 minutes while 40 trees required an estimated 251 minutes. Estimated cost to spray one tree was about $28 and the cost for 40 trees was estimated to be $105. The time spent and costs of control are similar for handpicking and spraying single trees. Handpicking may be acceptable on single or small numbers of short trees that may be safely handpicked. However, as the number of trees increases, time and costs associated with handpicking increase dramatically, while costs to spray increase only slightly.

Conservation biological control in urban landscapes: Manipulating parasitoids of bagworm (Lepidoptera: Psychidae) with flowering forbs

Abstract We conducted field experiments to test the hypothesis that regulation of herbivorous pests in urban landscapes can be enhanced with forbs that provide floral resources for adult natural enemies. The herbivore was bagworm, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae), which is attacked by a guild of hymenopterous parasitoids. We established host shrubs in common garden plantings, encircling some with flowering forbs, released bagworm larvae on shrubs, and assessed survivorship. The hypothesis was supported: parasitism rates of bagworm were 71% higher in shrubs that were surrounded by flowering forbs than in shrubs that lacked flowers. This study also suggested that white-footed mice and European sparrows were important predators of bagworms. The most abundant parasitoid species was the exotic ichneumonid Pimpla (=Coccygominus) disparis (Vierick), an introduced biological control agent of gypsy moth. In a second experiment, parasitism rates were at least three times higher in shrubs encircled by a high density of forbs compared to those having fewer or no forbs. In a third experiment, parasitism rates exceeded 70% in shrubs that were adjacent to a central bed of flowering forbs, but less than 40% in shrubs that were farther away. We conclude from these studies that flowering forbs have a localized effect on host-searching behavior of female parasitoids, encouraging them to parasitize bagworms in the immediate vicinity. This study provides further evidence that ecological methods of pest management can be integrated into the design of urban landscapes to improve regulation of herbivorous pests.

Aerial dispersal and host plant selection by neonate Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae)

Abstract. 1. Neonate evergreen bagworms, Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae), disperse by dropping on a strand of silk, termed silking, and ballooning on the wind. Larvae construct silken bags with fragments of plant foliage. This species is highly polyphagous, feeding on more than 125 species of woody plants of 45 families. The larvae commonly infests juniper (Juniperus spp.) and arborvitae (Thuja spp.), but rarely feed on deciduous hosts such as maples. The hypothesis is proposed that polyphagy in T. ephemeraeformis is maintained by variation among larvae in dispersal behaviour, and time constraints on the opportunity to disperse, but patterns of host species preference result from a predisposition for larvae to settle on arborvitae and juniper but disperse from other hosts.2. Consistent with that hypothesis, laboratory experiments revealed: (a) starved larvae varied in their tendency to disperse from paper leaf models; (b) starved larvae readily silked only during their first day; (c) larvae became increasingly sedentary the longer they were exposed to plant foliage; (d) when provided with several opportunities to silk, larvae became sedentary after exposure to arborvitae foliage, but repeatedly silked after exposure to maple (Acer species) foliage or paper; and (e) larvae were less inclined to silk from foliage of arborvitae than from maple.3. Field experiments supported the hypothesis by demonstrating that: (a) neonates tended to disperse from maple leaves while larvae older than 1 day tended to settle and remain; and (b) neonates were less likely to disperse from arborvitae and juniper trees than from maples.

Bagworm Survival and Feeding Preferences as Indicators of Resistance among Maples

Abstract The bagworm (Thyridopteryx ephemeraeformis (Haworth)) is a polyphagous, native pest of numerous deciduous and evergreen ornamental plants. Bagworm larvae were used to investigate host plant susceptibility among ten species and cultivars of maples that are economically important and commonly encountered in landscapes in the eastern United States. Data analyses from 48-hour choice assays, conducted in the laboratory during 2000 and 2001, indicated that differences existed among maples for bagworm feeding preferences and host plant susceptibility. Results from the 48-hour trials were not as accurate as seasonal no-choice assays, however. No-choice assays during both seasons quantified resistance among maples that limited larval bagworm survival and development. Measurements of larval feeding injury demonstrated resistance in paperbark maple (Acer griseum (Franch.) Pax) and trident maple (A. buergerianum Miq.) when compared with other maples. Laboratory results were corroborated during 2001 by a no-choice field assay, in which early instar bagworm larvae performed well on the majority of maples. In contrast, paperbark maple and trident maple were resistant to bagworm feeding, while ‘Autumn Blaze’ Freeman maple (A. x freemanii E. Murray), a hybrid cross obtained by breeding A. rubrum with A. saccharinum, showed moderate resistance.

Bags of the Bagworm <I>Thyridopteryx ephemeraeformis</I> (Lepidoptera: Psychidae) Protect Diapausing Eggs from Water Loss and Chilling Injury

Abstract The bagworm Thyridopteryx ephemeraeformis (Haworth) is univoltine and overwinters as diapausing eggs within the silken bag from the female moth. We have sought to determine whether selection of this overwintering site protects eggs against desiccation and low temperature injury. Bag-enclosed eggs retained water nearly three times more effectively (net water loss rates were lower) than naked eggs. A similar trend was noted in the ability of eggs to withstand prolonged exposure to subzero temperatures: naked eggs were four times more susceptible to chilling injury compared with those tucked inside a bag. Plastic or tissue paper artificial bags did not mimic the protection against cold. The eggs contained low levels of glycerol and sorbitol, suggesting no major role for these cryoprotectants. Bagworm eggs are not freeze tolerant, and their high water content implies that they have neither been enhanced for water conservation nor cold hardiness. These observations indicate that use of the female bag ...

Studies of Ballooning and Resulting Patterns of Locally Contagious Distribution of the Bagworm Thyridopteryx ephemeraeformis (Haworth) (Lepidoptera: Psychidae)

A series of field studies was stimulated by the unexpected finding of a band of junipers (Juniperus virginiana) bearing heavy infestations of bagworms, the band running south-southwest to north-northeast through a woodlot (near Norman, OK) of otherwise lightly infested trees. Fidelity to wind direction was confirmed, and numbers of bagworms ballooning from 3.05 m to 36.58 m was measured, with Tanglefoot® traps mounted on metal fence posts. Ballooning numbers were satisfactorily described with a negative exponential model incorporating both gravitational and trap losses. No significant difference was found between ballooning distances achieved by larvae with and without early-stage bags. A study of infestation levels on ornamental junipers planted around houses on the north and south sides of east-west streets revealed both a strong front- vs. backyard difference, and a weaker but statistically significant side-of-street effect. Patterns reflecting short-range dispersal were found in a linear windbreak planting of northern white cedar (Thuja occidentalis), and in a 12 × 44 = 528-tree lattice of planted junipers (near Urbana, Illinois). A “bonfire” effect showing heaviest infestations in mid-lattice, and reduced infestations on the periphery (especially on the windward edge) was postulated and confirmed. Studies of the effect of increased “target” size of larger trees, and of the incidence of apparent bird and small mammal predation, are also reported.

SEX-SPECIFIC HABITAT UTILIZATION BY BAGWORMS (LEPIDOPTERA: PSYCHIDAE)

Bagworms (Lepidoptera: Psychidae) have an unusual life history (Borror et al. 1989). Following eclosion, apterous females stay within their pupal case and the protective bag they constructed as larvae. Females attract winged males by expelling pheromone-impregnated scales outside of their pupal case into the lower extremity of the bag. Sexual segregation of pupation sites has been found in three bagworms, Thyridopteryx ephemeraeformis (Haworth) (Gross andFritz 1982), Oiketicus kirbyi (Guilding) (Rhainds et al. 1995a, 1995b), and Metisa plarza (Mlker) (Rhainds, unpublished). In all three bagworms, proportionately more female than male larvae pupate in the upper strata of trees. Pupation of females in upper sites is adaptive because it may enhance any to all of the following: pheromone dissemination (Gross and Fritz 1982), mate attraction (Rhainds et al. 1995a, 1995b), progeny development (Rhainds, unpublished), and dispersal of neonatal larvae (Cox and Potter 1988). We report habitat segregation between male and female pupae of the bagworm Clania cramerii (Mstwood) (Thangavelu and Ravindranath 1985).

Dicymolomia julianalis (Lepidoptera: Pyralidae) on Selected Hosts in Eastern and Middle Tennessee

The pyralid Dicymolomia julianalis (Walker) has an unusually diverse range of hosts. In this study, the life cycle, feeding habits, and biological control potential of D. julianalis were evaluated on 3 hosts (musk thistle, Carduus nutans L. ssp. leiophyllus (Petrovic) Stojanov & Stefanoff; the common bagworm, Thyridopteryx ephemeraeformis (Haworth); and cattail, Typha spp.) at 3 sites in eastern and middle Tennessee. During this 2-yr study, 3 generations per year of D. julianalis were inferred. The 1st, 2nd, and 3rd (overwintering) generations occurred on cattail, dead or dying musk thistle, and within bagworm egg clusters, respectively. Second-generation individuals also were reared from cattail. Of these 3 hosts, cattail is believed to be the primary host of D. julianalis throughout the year in Tennessee. Infestation levels, averaged across all sites, were 11.6, 14.2, and 95.0% on musk thistle, bagworm, and cattail, respectively. Larvae of D.julianalis may simply feed as scavengers within seed heads of musk thistle and have limited effect on seed production and survival of musk thistle. However, D. julianalis may have potential as a biological control agent of bagworm.