Evergreen Bagworm Moth

Thyridopteryx ephemeraeformis (Haworth)

Sphinx ephemeraeformis Haworth, 1803:72.

Thyridopteryx ephemeraeformis (Haworth).—Davis, 1964:134.

The predominantly eastern North American bagworm, Thyridopteryx ephemeraeformis, has been reported from the West Indies (Davis, 1964), but this evidence is still based primarily upon only three male specimens from the Bahamas and Haiti. The adult illustrated in Figure 16, represents the largest form typical of southern Florida and the West Indies. As would be expected, the head of the adult male of Thyridopteryx (Figures 36, 37) demonstrates greatest affinities to that of Oiketicus. The maxillae, however, are even more reduced, and the labial palpi are shorter in length with the basal portion more strongly fused.

Seventeen larval cases, a few containing poorly preserved larvae, have been examined from Puerto Rico that may represent this species. The largest of these cases (30 mm long) are somewhat small for mature larvae of T. ephemeraeformis, but they do resemble cases of this species reared from Thuja occidentalis in the United States. The resemblance, however, may be due simply to the fact that the Puerto Rican larvae were collected from a related host, Thuja orientalis. Hopefully, adults will eventually be reared from this population.

HOSTS.—Over 125 species of plants have been reported as hosts (Davis, 1964) with members of the Cupressaceae being particularly favored.

WEST INDIAN DISTRIBUTION.—Bahamas: Specific locality unknown: 1 (BM). Nassau, 1 , 3 Jan. (BM). Haiti: Port-au-Prince: 1 (ZMNU). Puerto Rico: Guaynabo, Parkville: 12 larval cases (determination questionable), 18 Nov. (UPR); 5 larval cases (determination questionable), 18 Nov. (USNM).

Unidentified Species

On the following pages I have followed the procedure in my 1964 revision for several species that cannot be named at this time because of insufficient or otherwise inadequate material. Indeed, no new specific names should be proposed for these insects until the adult males have been reared and properly described. The reason for this being, that within this troublesome family it is the adult male that is the ultimate basis for both specific and generic delimitation. The purpose in mentioning these oddities is to attract the attention of future students and collectors. The numerical sequence used is a continuation of that followed previously (Davis, 1964:156–158).

Species No. 4: Oiketicus species

This species is typified by larval cases usually 60–70 mm long that are without an external sheath of silk but are covered by closely appressed, interwoven fragments of leaves (Figures 204, 205), or, in some individuals, with more loosely attached, divergent leaves. The adults are still unknown. The larval cases most resemble those of O. toumeyi Jones but may represent a rather unusual variation of O. abbotii Grote. Several cases have been reported from Cuba (Davis, 1964: 156), and one specimen of perhaps the same species has been collected in Jamaica.

HOST.—“An Mandelbaun” (from specimen label).

WEST INDIAN DISTRIBUTION.—Cuba: Havana: 11 cases (IPK); 1 case (USNM). Jamaica: St. Ann Parish: Clarement, 534 m (1750 ft): 1 case, Mar. (USNM).

Species No. 6

Larval cases of this insect were previously reported (Davis, 1964) from Haiti and were characterized as having the exterior of the bag usually covered with long, slender stems of grasses, or other plants, applied longitudinally. Frequently these plant fragments extend the entire length of the case (12–14 mm) or even beyond. As I mentioned in my earlier report, these cases most closely resemble those constructed by larvae of Epichnopteryx and Psyche (=Fumea and Fumaria auct.). The adult stage is still unknown although similar bags (Figure 196) have been collected in Trinidad by Miss Cruttwell. Her material may represent a different species, but they do fall within the same size range (11–12 mm). In her report (in press) on the bagworms of Trinidad, Miss Cruttwell states that the species was rarely encountered. All larval cases from Trinidad were collected on low growing herbs, and one was found on Eupatorium odoratum L.

HOST.—Asteraceae, “Eupatorium odoratum L.” (Cruttwell, in press).

WEST INDIAN DISTRIBUTION.—Haiti: Aux Cayes: 4 larval cases, 15–18 Mar. (AMNH). Petionville, 457–915m (1500–3000 ft): 4 larval cases, 26–28 Jan. (AMNH). Trinidad: Curepe: 2 larval cases, Dec. (USNM).

Species No. 7: Oiketicus species

Five larval cases have been collected in Jamaica that do not resemble that of any species of Oiketicus known to occur in the Antilles. The larger examples bear a strong resemblance to cases of O. geyeri, a widespread South American species, which has never been collected in the West Indies. It is possible that these bags are simply a variant of Oiketicus species no. 4. Two of the cases contained fragmentary pupal remains.

LARVAL CASE (Figure 206).—Length 40–65 mm in length; greatest diameter 7–12 mm. Exterior of case typically smooth, naked, and covered with grayish white silk; sometimes with short (5–10 mm long) plant stems arranged longitudinally along length of case.

HOST.—Unknown.

WEST INDIAN DISTRIBUTION.—Jamaica: Specific locality unknown: 3 larval cases (USNM). Falmouth: 1 larval case (USNM), Rose Hill, Runaway Bay, St. Ann Parish, 274 m (900 ft): 1 larval case, 29 Apr. (USNM).

Species No. 8

Only one larval case of this unidentified species is known. It was collected in December in Curepe, Trinidad, by Miss Cruttwell. The host is not known, although judging from the construction of the larval case, the species is probably lichen- ivorous. The structure of the bag most resembles that of “Clania” licheniphilus or Dendropsyche burrowsi and may be briefly characterized as follows:

LARVAL CASE (Figure 197).—Dimensions: length, 9 mm; diameter, 2 mm. Fusiform in outline; exterior of case gray with irregular bands and patches of white; walls relatively smooth, covered with minute particles of plant material overlying a thin silken base.

Species No. 9

Several moderately large larval cases have been collected in Jamaica for which no adult or immature specimens have been preserved. Most of the bags are simply labeled “Jamaica,” although a more precise locality is provided for some; the latter were collected at Claremont, St. Ann Parish, in March at an elevation of 534 m (1750 ft). Pupal and larval remains are present inside some of the cases, but these are too fragmentary for description. It is possible that the bags were produced by a rather large species of Cryptothelea, possibly C. watsoni. The 30 larval cases are deposited in the collection of the National Museum of Natural History, Smithsonian Institution, and may be characterized as follows;

LARVAL CASE (Figures 193, 194).—Dimensions: length, 20–29 mm; diameter, 6–8 mm. Fusiform in shape; exterior of case dark, heavily covered with small particles of plant material and usually with a few medium (6–8 mm long) to large (10–15 mm long) sections of cut stems; stems normally applied lengthwise to case but occasionally may project out at nearly right angles. Walls of case thin and flexible.

Species No. 10: Prochalia species

This species is represented by a single adult male (Figure 4) collected 13 August 1931 at Santiago de las Vegas, Cuba. Unfortunately, the missing abdomen makes it impossible to identify the species, although it is known to belong to the genus Prochalia. It agrees with that genus in all major features of the antennae, legs and wing venation (Figure 62). The radial venation of the forewings differs slightly from that figured for Prochalia pygmaea Jones (Davis, 1964), but these set of veins are particularly variable in this genus. As mentioned earlier, it is possible that this specimen may be the adult of “Clania” licheniphilus. The unique specimen is deposited in the National Museum of Natural History, Smithsonian Institution.

larva crawling Thyridopteryx ephemeraeformis, evergreen bagworm Thyridopteryx ephemeraeformis, evergreen bagworm

The evergreen bagworm (Thyridopteryx ephemeraeformis), commonly known as bagworm, eastern bagworm, common bagworm, common basket worm, or North American bagworm, is a moth that spins its cocoon in its larval life, decorating it with bits of plant material from the trees on which it feeds.

The evergreen bagworm's case grows to a length of over 6 cm, tapered and open on both ends. Newborn larvae are blackish and turn brown to tan as they grow, mottled with black. The heads and thorax develop a yellow tint as they grow to a full length of 24 to 32 mm. Adult males resemble bees, having a 25 mm wingspan with transparent wings (thuris window + pterux wing) and black furry bodies. Adult females are maggot-like with yellowish-white soft bodies 19 to 23 mm long and small tufts of hair near the end of the abdomen. The cream-colored eggs are 0.75 mm in diameter.

The evergreen bagworm thrives in the eastern United States as far west as Nebraska, north into New England and bordering the Gulf of Mexico south throughout Texas. It has been found in other countries, such as South Africa, Croatia, and in the north-east of Iran. Large populations in forested areas are rare. With scarce predators in urban areas, evergreen bagworms often thrive in urban habitats. When disturbed, the larva will retract its head into its case and hold the front opening closed. Mature larvae may remain in the host tree or drag its case nearby before attaching itself for the pupa stage.

The diet of larvae consists of leaves and buds of trees. Arborvitae and red cedar are favored host trees. Cypress, juniper, pine, spruce, apple, birch, black locust, elm, maple, poplar, oak, sycamore, willow, and over 100 other species can also be eaten.

Bagworms are commonly parasitized by ichneumonid wasps, notably Itoplectis conquisitor. Predators include vespid wasps and hornets. Woodpeckers and sapsuckers can feed on the larvae from their cases.

Eggs hatch from early April to early June (earlier in the south) and larvae emerge from the carcass of their mother in her case. Newborn larvae emerge from the bottom of the hanging case and drop down on a strand of silk. The wind often blows the larva to nearby plants where it begins its new case from silk and fecal material before beginning to add leaves and twigs from its host. When mature in mid-August, the larva wraps silk around a branch, hangs from it, and pupates head down. The silk is so strong that it can strangle and kill the branch it hangs from over the course of several years as the branch grows. Adult males transform into moths in four weeks to seek out females for mating. The female never leaves the cocoon, requiring that the male mate with her through the open end at the back of the case. She has no eyes, legs, wings, antennae, and can't eat, but she emits a strong pheromone to attract a mate. After her death with hundreds to several thousand eggs still inside, her offspring hatch and pass through her body, pupal shell and case over several months emerging to start their own cases. Later, her pupal case can be found, full of the yellow remains of eggshells.

The bagworm has a voracious appetite and is considered a serious pest. Host trees develop damaged foliage that will kill the tree if left unchecked. If caught early enough in an infestation, the cases from the previous year can be picked off by hand before the end of May. They are easiest to detect in the fall after their cases have turned brown, especially on evergreen trees. Various bacterial sprays such as Bacillus thuringiensis Bt/Spinosad and stomach insecticides such as carbaryl (Sevin) are used to control infestations.