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85(3), 1983, pp. 426-434 


A. G. Wheeler, Jr. and Gary L. Miller 

(AGW) Bureau of Plant Industry, Pennsylvania Department of Agriculture, 
Harrisburg, Pennsylvania 17110; (GLM) Department of Entomology and Plant 
Pathology, University of Tennessee, Knoxville, Tennessee 37901. 

Abstract. history of the rhopalid Harmostes fraterculus (Say) was 
followed in south central Pennsylvania during 1978-81. Adults of this more 
southern, apparently migrant species appeared in late July to early August. A first 
Pennsylvania generation developed in flower heads of the composite Eupatorium 
fistulosiim Barratt in August and early September; a second generation was pro- 
duced on this host and on E. perfoliatum L. during mid-September and October. 
A hypothesis is proposed to explain its migratory flight. Notes on oviposition and 
mating behavior are given, duration of the egg and nymphal stages is recorded, 
and all immature stages are described and illustrated. 

Harmostes fraterculus, described from Indiana and Georgia in the genus Syr- 
omastes (Say, 1831), was placed in the largely Neotropical genus Harmostes Bur- 
meister by Stal (1870). One of the few widely distributed species of the genus in 
North America, this rhopalid is uncommon in most collections and apparently 
is less frequently collected than the wide-ranging H. reflexulus (Say). Torre-Bueno 
(1941) defined the range of H. fraterculus as New Jersey south to Florida, west 
to California and Arizona, and through Mexico into Central America. In a generic 
revision, Gdllner-Scheiding (1978) noted that in the eastern United States she 
had seen specimens from as far north as Pennsylvania. Harmostes fraterculus is 
known to occur as far south as Guatemala and in South America is replaced by 
the closely related H. parafraterculus, described by Gollner-Scheiding (1978). 

With the exception of Yonke and Walker’s (1970a, b) study of H. reflexulus, 
the field biology and immature stages of Harmostes species are poorly known. 
Information on H. fraterculus is limited to notes on habits and host associations. 
Rosenfeld (1911) observed adults overwintering in Spanish moss in Louisiana. 
Blatchley (1926), Froeschner (1942), and Hoffman (1975) reported collections 
from “boneset” and “Joe Pye weed,” plants of the composite genus Eupatorium. 
Nymphs have been found on various ragweed species in southern California: 
Ambrosia acanthicarpa Hooker (Goeden and Ricker, 1974), A. dumosa (Gray) 
Payne (Goeden and Ricker, 1976a), and A. chenopodiifolia (Benth.) Payne (Goe- 
den and Ricker, 1976b). In Mexico, Brailovsky and Soria (1981) collected fra- 
terculus on composites of the genera Eupatorium, Haplopappus, and Verbesina. 



In September 1 978 we found large populations of H. fraterculiis on Eiipatoriiim 
fistulosum Barratt at two sites near Harrisburg, Pennsylvania. We had not collected 
this rhopalid previously in the state, and the few Pennsylvania specimens we 
located in various insect collections had been taken in late summer or early fall. 
Coupled with its absence from nearby colonies of the same host, we suspected 
H. fraterculus was a migrant in Pennsylvania, populations occurring north of the 
permanent range only in certain years, as is known for heteropterans like the 
harlequin bug, Murgantia histrionica (Hahn). We began studies in 1979 to elu- 
cidate the seasonal history of Pennsylvania populations and to determine whether 
this rhopalid overwinters in the state. In this paper we present a generalized 
seasonal history for H. fraterculus in Pennsylvania, report on certain aspects of 
its habits in the laboratory, and describe and illustrate the immature stages. 

Study Areas and Methods 

Field studies.— Seasonal history was observed periodically at two sites near 
Harrisburg (Dauphin Co.), Pennsylvania, from late September to early November 
1978 and at regular intervals at these and additional areas during 1979-81. The 
main sites for field work, about 1 0 km apart, were low-lying areas along streams 
that were dominated by colonies of Joe-Pye weed, Eupatorium fistulosum, a 
perennial herb of moist habitats which, like most members of the genus, has 
corymbose, discoid heads. Boneset, E. perfoliatum L., was common at one of the 

During spring and early summer 1979-82 we collected extensively near the 
study areas to try to find overwintering individuals of H. fraterculus; once flower 
buds of E. fistulosum were well developed (late June to early July), we concentrated 
on sampling the host plants rather than on general collecting. When adult rhopalids 
appeared on the hosts (late July to early August), we sampled the plants weekly 
or biweekly through September in 1979 and until mid-October in 1980; periodic 
observations were continued until November. Samples were taken by tapping 
flower heads of the host over a small tray, collecting 10 to 20 nymphs (except 
when first instars were scarce in early samples), and sorting them to stage in the 
laboratory. The relative proportion of adults to nymphs was estimated in the field 
at each sample date. 

Laboratory studies. — Field-collected adults were placed in small, plastic petri 
dishes containing florets of E, fistulosum and a source of moisture, and were held 
at 20-22°C under an approximate 12-h photoperiod. We made notes on mating 
and oviposition behavior and removed eggs to individual dishes to determine 
incubation times and duration of nymphal stages. We tried to rear H. fraterculus 
on sunflower seeds soaked in water and cracked in half, the technique used by 
Yonke and Walker (1970a) to rear H. rejlexulus. The mortality, however, was so 
great, particularly with early-stage nymphs, that we had to substitute excised disc 
flowers of Joe-Pye weed. A small portion of the cyme, consisting of 6-8 capitula, 
was cut from a flower head and the stalk inserted through Parafilm" stretched 
over the opening of a glass genitalia vial filled with water. Even then, a high 
mortality prevented us from rearing any individual from egg to adult. Therefore, 
the developmental times obtained are based partially on determination of instars 
for field-collected nymphs of various stages. 




Fifth instar (in alcohol, n = S) (Fig. 1). — Elongate-pyriform, somewhat dorso- 
ventrally flattened, testaceous, mottled or reticulate with brown or reddish brown, 
often forming small to large testaceous spots, a pale stripe along meson from 
anterior margin of pronotum onto scutellum. Antenna cylindrical, segment I 
shorter, broader, II and III distinctly flattened, IV fusiform. Dorsum covered with 
numerous fine setae, most arising from tubercles or white papillae. Wing pads 
reaching 3rd or 4th abdominal segment, their apices sometimes dark brown; dorsal . 
abdominal scent glands opening between tergites IV-V and V-Vl, surrounded by 
dark rims; trichobothrial pattern as in Fig. 2. Legs dark brown, femora with small 
testaceous spots; metafemora with 2 stout spines on ventral aspect near apex. 

Length 4.58-6.17 mm, x = 5.55. Head, length 1.04-1.20 mm, y = 1.16; width 
0.90-1.00 mm, x = 0.95; interocular space 0.64-0.70 mm, a= 0.66. Protergal 
length 0.60-0.64 mm, a' = 0.62; humeral width 1.54-1.64 mm, x = 1.60. Anten- 
nal lengths I, 0.36-0.40 mm; II, 0.66-0.70; III, 0.68-0.74; IV, 0.60-0.64. Labial 
lengths I, 0.80-0.86 mm; II, 0.70-0.74; III, 0.66-0.78; IV, 0.62-0.70, reaching 
beyond metacoxae to 2nd abdominal segment. 

Fourth instar (in alcohol, /? = 3 (Fig. 3). — Form and color similar to 5th instar, 
the white papillae on dorsal surface of abdomen and spines on metafemora less 
distinct. Wing pads reaching 2nd abdominal segment. 

Length 3.84-4.40 mm, x= 4.16. Head, length 0.94-1.10 mm, Jv = 1.04; width 
0.76-0.80, X = 0.78; interocular space 0.52-0.54 mm, x = 0.53. Protergal length 

0. 42-0.46 mm, a = 0.44; humeral width 1 . 12-1.16 mm, x= 1.13. Antennal lengths 

1, 0.30-0.34 mm; II, 0.52; III, 0.54-0.56; IV, 0.50-0.52. Labial lengths I, 0.66- 
0.70 mm; II, 0.60; III, 0.52-0.60; IV, 0.60-0.64. 

Third instar (in alcohol, n = 4) (Fig. 4).— Similar to preceding instar, but more 
elongate, the reddish markings less intense, the tubercles and white papillae less 
distinct. Mesothoracic wing pads covering metathoracic pads, which extend to 
1st abdominal segment. Labium reaching 3rd abdominal segment. 

Length 2.60-3.20 mm, a' = 2.96. Head, length 0.74-0.80 mm, a = 0.78; width 
0.60-0.62 mm, a= 0.61; interocular space 0.42-0.44 mm, a= 0.43. Protergal 
length 0.26-0.28 mm, a = 0.27; humeral width 0.76-1.04 mm, a = 0.85. Anten- 
nal lengths I, 0.20-0.28 mm, II, 0.36-0.40; III, 0.40-0.42; IV, 0.40-0.44. Labial 
lengths I, 0.50-0.52 mm; II, 0.44-0.46; III, 0.40-0.46; IV, 0.50-0.54. 

Second instar (in alcohol, ^ = 4) (Fig. 5). — More pyriform and paler than pre- 
ceding instar; integument appearing more smooth. 

Length 2.04-2.20 mm, a = 2.09. Head, length 0.58-0.64 mm, a = 0.61; width 
0.40-0.46 mm, a = 45; interocular space 0.28-0.34 mm, a = 0.33. Protergal length 

0. 1 6-0. 18 mm, A = 0. 1 7; humeral width 0.48-0.68 mm, a = 0.61. Antennal lengths 

1, 0.14-0.18 mm; II, 0.24-0.28; III, 0.28-0.30; IV, 0.32-0.34. Labial lengths I, 
0.36-0.40 mm; II, 0,34-0.40; III, 0.30-0.32; IV, 0.42-0.44. 

First instar (in alcohol, n = 2) (Fig. 6). — More elongate, less dorsoventrally 
flattened than preceding instars; dorsal abdominal scent gland openings indistinct; 
labium sometimes extending beyond abdomen. 

Length 1.40-1.42 mm, a = 1.41. Head, length 0.42-0.44 mm, a = 0.43; width 
0.34; interocular space 0.24-0.26, a = 0.25. Protergal length 0.28-0.30 mm, a = 
0.29; humeral width 0.36-0.40 mm, a= 0.38. Antennal lengths I, 0.14 mm; II, 



Figs. 1-4. Hannostes fmterculus nymph. 1, Fifth instar. 2, Trichobothrial pattern of fifth instar; 
diagram represents left side of abdominal sterna II-VII and shows trichobothria (X) and spiracles (O). 
3, Fourth instar. 4, Third instar. 

0.20-0.22; III, 0.24-0.26; IV, 0.30-0.34. Labial lengths I, 0.34-0.38 mm; II, 0.32; 
III, 0.30-0.32; IV, 0.40. 

Egg (« = 5) (Fig. 7).-Length 1.00-1.06 mm, x = 1.03. Elongate oval, white 
when deposited, turning orange to dark brown before hatching, distinct sculpturing 



Figs. 5-7. Harmostes fraterculus nymph and egg. 5, Second instar. 6, First instar. 7, Egg. 

apparently absent; 2 distinct micropylar processes or aero-micropyles at anterior 
pole, the form typical of rhopalid eggs except for absence of a ventral attachment 
stalk (see Southwood, 1956; Cobben, 1968). 


Seasonal history.— Adults first appeared on flower heads of their host plants 
during the last week of July in 1979 and the first week of August in 1980, just as 
a few flowers of Joe-Pye weed were beginning to open. In both years the seasonality 
of populations was similar, and the phenological pattern here presented is based 
on a composite of 1979-80 samples supplemented by observations made in 1978 
and 1981. 

During the week following their first collection, adults increased noticeably in 
numbers, and mating pairs were observed on flower heads of E.fistulosum. First- 
instar nymphs were found two to three weeks after the appearance of adults, and 



Table 1 . Duration (in days) of egg and nymphal stages of Harmostes fraterciihis reared at 20-22°C. 





Mean ± 5 * 

Mean Age 




8.2 ± 0.40 


Nymphal stages 




3.3 ± 0.61 





3.3 ± 0.98 





3.3 ± 0.90 





4.1 ± 1.13 





5.4 ± 1.02 


* Standard deviation. 

by late August populations consisted mainly of third instars. Oviposition appar- 
ently continues for several weeks because nymphs of three stages often were present 
in samples; occasionally all five stages were found. Teneral adults of a first Penn- 
sylvania generation were observed during the first week of September when fourth 
and fifth instars were predominant in the population. 

During mid-September, the number of first-generation adults increased, late- 
instar nymphs were still common, and eggs and instars I~II of a second generation 
were observed. With a deterioration of food resources on their hosts, late-ma- 
turing, first generation females appeared to oviposit mainly in the few flowering 
heads that remained; late in the season adults and nymphs were most abundant 
in heads bearing a few flowers, or in withered heads that had not completely 
dried. Although the first generation was found only on E. fistulosum at the sample 
sites (and once on the Joe-Pye weed E. purpiireum L. in a nearby, much drier 
habitat), the second generation developed partially in heads of boneset, E. per- 
foliatum, occurring near patches of E. fistulosum. Boneset flowers usually were 
available for several weeks after those of Joe-Pye weed had dried up. 

Adults of the second generation were observed as early as the last week of 
September. A few fifth instars were present until mid-October, and adults could 
be found until late October or early November. 

Laboratory studies. — Field-collected pairs mated readily in rearing containers, 
sometimes remaining in copula for several hours. In an apparent absence of 
elaborate pre-copulatory behavior, the male simply crawled over the female; if 
receptive, she remained motionless, and he inserted his aedeagus. At first, the 
pair assumed a side-to-side position, then often oriented tail-to-tail. Mutiple 
matings were observed for several pairs. 

The single female observed in oviposition crawled over and probed the excised 
florets, and thrust her ovipositor into the disc flowers. Oviposition times ranged 
from 35 s to 1 min 5 s (Jc = 53 s, n = 5). Eggs usually were deposited singly into 
disc flowers and placed on the inner edge of involucral bracts, on ovaries, or on 
the pappus; a few were laid in clusters of two or three. 

The average incubation time was 8.2 days (Table 1). Instars I-III each averaged 
3.3 days; the duration of the fourth stage was slightly longer, and the fifth stage 
was the longest. We were unable to rear H. fraterculus from egg to adult, and the 
average of 19.4 days required for nymphal development is based partly on times 
determined for field-collected nymphs. Even though our data cannot be compared 



directly to those of Yonke and Walker (1970a), who reared 67 nymphs of H. 
reflexiihis from egg to adult, our 19.4 days is close to the 21.7 days required for 
the development of rejlexuhis nymphs. 


Our field studies, although contributing to the biological knowledge of a poorly 
known species, raise several questions. Is Harmostes fraterculus capable of over- 
wintering in south central Pennsylvania? Based on the data now available, we 
believe this rhopalid migrates into the area during late summer of most years and 
is near the northern limits of its range. The only evidence tending to negate a 
migratory theory is the appearance of populations at the sample sites for three 
consecutive seasons; one might not expect a ‘Tall out” to occur each season in 
the same colonies of Eupatorium. Still, the large size of the colonies under ob- 
servation and the patchiness of rhopalid populations in nearby areas, coupled 
with the additional information to be presented, reinforce our original assumption 
regarding the status of H. fraterculus in Pennsylvania. 

Pennsylvania specimens of this rhopalid are scarce in the insect collections we 
examined (American Museum of Natural History— AMNH; Cornell University— 
CU; New York State Museum — NYSM; and National Museum of Natural His- 
tory— USNM), and none was taken before August. Gollner-Scheiding’s (1978) 
record is the only published one from the state. In tracking Joe-Pye weed north 
from the Harrisburg area, we found populations in Columbia and Northumberland 
counties, but we did not collect specimens in the extreme northern counties or 
in southern New York. There are no New York specimens in the collections of 
AMNH, CU, NYSM, or USNM. The Canadian record Gollner-Scheiding (1978) 
had in mind undoubtedly is that of Provancher (1886), which was based on a 
misidentification of the lygaeid Ortholomus scolopax {Sdiy) (see Van Duzee, 1912: 
319; Slater, 1964: 341). 

At the two main sample sites and additional areas near Harrisburg we have 
never encountered adults of H. fraterculus before late July, even though extensive 
surveys have been conducted for this study and as part of projects involving other 
insects. We have, however, made early-season collections of adults of H. reflexulus 
and have found nymphs developing on yarrow, Achillea millefolium L., during 

It appears that H. fraterculus overwinters within 100 miles of Harrisburg. We 
have seen specimens collected from early April and May in the northern Virginia 
and Washington, D.C., area (CU, USNM) and one taken “under sign board on 
tree” at Cape May Courthouse, N.J., on March 29 (AMNH). 

Like H. reflexulus, H. fraterculus apparently overwinters in the adult stage in 
its permanent range, at least as far north as the Washington area and southern 
New Jersey. This rhopalid is closely associated with Joe-Pye weed, not only in 
Pennsylvania but farther south; we have collected nymphs from E. fistiilosum 
(and Conyza canadensis (L.) Cronq.) in North Carolina. Eupatorium spp. and C. 
canadensis do not bloom until mid- to late summer. What happens to populations 
of the rhopalid earlier in the season? Have early-season generations been over- 
looked on a composite of the same tribe or some other composite? Does the bug 
use a succession of hosts like H. reflexulus (Yonke and Walker, 1970a) and the 
lygaeids Lygaeus equestris L. (Solbreck and Kugelberg, 1972) and L. kalmii L. 



(Hunt, 1979)? Or, in the northern fringes of its range, is fmterculus ''getting by” 
on plants of unrelated families before Eupatorium comes into bloom? Is it possible 
that this rhopalid, essentially a southern species that ranges into Central America, 
does not breed until late summer under more northern photoperiods? The pen- 
tatomid Proxys punctidata (Palisot de Beauvois) has a similar range, and breeding 
populations are known from as far north as southern Illinois where adults do not 
emerge from overwintering sites and begin to reproduce until mid- to late June 
(Vangeison and McPherson, 1975). 

Although further study is needed to clarify some of these points, we believe the 
following summary provides the most logical explanation of seasonality for H. 
fraterculus in Pennsylvania. Our hypothesis also may be relevant to populations 
of other rhopalids and to certain species in other families of Hemiptera-Heter- 

As a specialist herbivore on flower heads of composites growing in somewhat 
temporary habitats, H. fraterculus engages in migratory or nontrivial flights. Rho- 
palid adults have been collected by day at heights of 200-5000 ft. (61-1523 m) 
and at night at 500-5000 ft. (152-1253 m) (Click, 1939). Southwood and Leston 
(1959) regard the rhopalid Liorhyssiis hyalinus (F.) as a migrant insect in England. 
For //. fraterculus, migratory movements, perhaps combining active flight with 
passive dispersal on convective air currents, could be nonspecific in direction but 
still adaptive because food resources presumably would be available in all direc- 
tions and at all distances. As Dingle (1972) and others have noted, most small 
migrant insects undergo unspectacular movements that make migratory flights 
difficult to detect. Outbursts or irruptions of H. fraterculus in all directions from 
a "core” population most likely would be detected only in areas north of the 
permanent range, e.g., Pennsylvania. In most cases of successful colonization of 
Eupatorium, the rhopalid would be able to overwinter. In Pennsylvania there also 
is the possibility of a late-fall, return flight. In northern areas of its range, the large 
milkweed bug, Oncopeltis fasciatus (Dallas), is thought to migrate south with 
northerly winds as day length decreases in autumn (Dingle, 1972). 


We are grateful to E. R. Hoebeke (Department of Entomology) and R. B. Root 
(Section of Ecology and Systematics), Cornell University, for reading an early 
draft of the manuscript. We have benefitted from discussing with them the sea- 
sonality of H, fraterculus', the authors, however, assume responsibility for state- 
ments concerning migratory behavior in this rhopalid. 

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