Identification, Biology, Impacts, and Management of Stink Bugs (Hemiptera: Heteroptera: Pentatomidae) of Soybean and Corn in the Midwestern United States

Koch, Robert L.; Pezzini, Daniela T.; Michel, Andrew P.; Hunt, Thomas E.

doi:10.1093/jipm/pmx004

Stink bugs (Hemiptera: Heteroptera: Pentatomidae) are an emerging threat to soybean and corn production in the midwestern United States. An invasive species, the brown marmorated stink bug, Halyomorpha halys (Stål), is spreading through the region. However, little is known about the complex of stink bug species associated with corn and soybean in the midwestern United States. In this region, particularly in the more northern states, stink bugs have historically caused only infrequent impacts to these crops. To prepare growers and agricultural professionals to contend with this new threat, we provide a review of stink bugs associated with soybean and corn in the midwestern United States. Descriptions and images of common stink bug species are provided as a diagnostic aid. The biologies and impacts of stink bugs to crops are discussed, with particular attention to differences among species. Based primarily on information from southern states, scouting, thresholds, and insecticide-based management of these pests are discussed. It is hoped that this review will provide stakeholders sufficient information for management of these pests, until more region-specific research can be performed on stink bugs in soybean and corn in the midwestern United States.

The midwestern United States is the top Glycine max L. Merrill (soybean)- and Zea mays L. (corn)-producing region of the United States (National Agricultural Statistics Service [NASS] 2015). In this region, the stink bug (Hemiptera: Heteroptera: Pentatomidae) fauna is relatively diverse, comprising 45–57 species per state (McPherson 1982, Packauskas 2012, Rider 2012, Sites et al. 2012, Swanson 2012, Koch et al. 2014) and includes species known to be pests of corn and soybean in some regions (McPherson and McPherson 2000, Panizzi et al. 2000).

The significance of stink bugs in the midwestern United States is increasing. First, an invasive species of Asian origin, Halyomorpha halys (Stål) (brown marmorated stink bug), is invading the region (Tindall et al. 2012, Koch 2014). This species was first collected in North America in Pennsylvania in 1996 (Hoebeke and Carter 2003) and has since spread throughout much of the continental United States (Leskey et al. 2012a, Rice et al. 2014). Halyomorpha halys is a pest of many crops, including soybean and corn (Leskey et al. 2012a, Lee et al. 2013, Rice et al. 2014). Economically significant infestations of this pest in fruit, vegetable, and field crops had been limited primarily to the mid-Atlantic region of the United States (Leskey et al. 2012a, Rice et al. 2014) but are expanding westward into the midwestern United States (http://www.stopbmsb.org/where-is-bmsb/state-by-state/). As populations of this species increase in the midwestern United States, increasing frequencies of economically significant infestations are likely. Since 2012, H. halys has been regularly found in Ohio soybean fields and sometimes at economic levels with other stink bug species (Michel et al. 2013). Another invasive species, Piezodorus guildinii (Westwood) (redbanded stink bug), is currently established in the southeastern United States and may be expanding its range northward (Tindall and Fothergill 2011). Piezodorus guildinii is a significant pest of soybean (McPherson and McPherson 2000, Panizzi et al. 2000). In addition to the spread of new invasive species, the abundance of native stink bug species appears to be increasing in the midwestern United States (Hunt et al. 2011, 2014; Michel et al. 2013). In particular, Chinavia hilaris (Say) (green stink bug), Euschistus servus (Say) (brown stink bug), Euschistusvariolarius (Palisot de Beauvois) (onespotted stink bug), and Thyanta custator accerra McAtee (redshouldered stink bug) have been increasing in abundance and frequency for the past several years (Michel and Hunt, personal observations).

Owing to the growing attention stink bugs are receiving in the midwestern United States and the lack of a recent, comprehensive resource accessible to agricultural professionals, agency and Extension staff, and producers, we compiled this review of the identification, biology, impacts, and management of stink bugs in soybean and corn in the midwestern United States.

Identification

General

Stink bugs vary in shape and size, but are generally described as having round or oval (sometimes shield-shaped) bodies, a well-developed and often triangle-shaped scutellum, piercing–sucking mouthparts, and five-segmented antennae (Slater and Baranowski 1978, McPherson 1982, Panizzi et al. 2000; Figs. 1 and 2). At least 24 species or subspecies of stink bugs could potentially be encountered in soybean and corn in the midwestern United States (Table 1). This list was created by developing and cross-referencing lists of species of stink bugs known to occur in the midwestern United States [based on McPherson (1982), Packauskas (2012), Rider (2012), Sites et al. (2012), Swanson (2012), and Koch et al. (2014)] and species of stink bugs reported from soybean and corn [based on McPherson (1982), Panizzi and Slansky (1985), McPherson and McPherson (2000), and several more recent crop-specific publications (see table footnotes)]. Some of these species have less extensive geographic ranges and do not occur in all parts of the midwestern United States (e.g., P. guildinii is more of a southern species). Depending on geography within the midwestern United States or species of interest, several diagnostic keys for stink bug identification are available, including McPherson (1982) for stink bugs and relatives of northeastern North America, McPherson and McPherson (2000) for stink bugs of economic importance, Rider (2012) for stink bugs and relatives of North Dakota, Paiero et al. (2013) for stink bugs and parent bugs of Ontario, Packauskas (2012) for stink bugs of Kansas, and Swanson (2012) for stink bugs and relatives of Michigan. The electronic key by Paiero et al. (2013) is particularly user friendly with many color photographs.

Fig. 1

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Line drawing of stink bug adult showing body parts important for discrimination of species common in soybean and corn in the midwestern United States (image credit: A.K. Tran).

Fig. 2

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Stink bug adults commonly encountered in soybean and corn of the midwestern United States: (A) Podisus maculiventris, (B) Chinavia hilaris, (C) Halyomorpha halys, (D) Thyanta custator accerra (green), (E) Thyanta custator accerra (brown), (F) Euschistus servus euschistoides, and (G) Euschistus variolarius (photo credits: C. Kurtz and C. Philips, and modified by D. Pezzini).

Table 1

Plant-feeding stink bugs potentially encountered in soybean and corn of the midwestern United States (“X” indicates reported presence of a species in a particular crop)

Scientific name	Common name	Soybean	Corn
Banasa dimidiata (Say)^a^,^b^,^c^,^d^,^e		X^g
Banasa euchlora Stål^a^,^b^,^c		X^g
Chinavia hilaris (Say)^a^,^b^,^c^,^d^,^e	Green stink bug	X^f^,^g^,^h^,^j^,^k^,^l	X^f^,^h^,ⁱ^,^j
Chinavia pensylvanica (Gmelin)^c^,^d^,^e		X^g
Chlorochroa persimilis Horvath^a^,^b^,^c^,^d^,^e		X^l	X^f^,^h^,ⁱ^,^j
Coenus delius (Say)^a^,^b^,^c^,^d^,^e		X^f^,^l
Cosmopepla lintneriana Kirkaldy^a^,^b^,^c^,^d^,^e		X^l	X^j
Euschistus ictericus (L.)^b^,^c^,^d^,^e		X^f^,^g^,^k^,^l	Xⁱ^,^o
Euschistus servus (Say)^a^,^b^,^c^,^d^,^e	Brown stink bug	X^f^,^g^,^h^,^j^,^k^,^l	X^f^,^h^,ⁱ^,^j^,^o
Euschistus tristigmus (Say)^a^,^b^,^c^,^d^,^e	Dusky stink bug	X^f^,^g^,^h^,^k^,^l	Xⁱ^,^o
Euschistus variolarius (Palisot de Beauvois)^a^,^b^,^c^,^d^,^e	Onespotted stink bug	X^f^,^g^,^h^,^j^,^l	X^f^,^g^,^o
Halyomorpha halys (Stål)^c^,^d^,^e	Brown marmorated stink bug	X^m	X^m
Holcostethus limbolarius (Stål)^a^,^b^,^c^,^d^,^e		X^f^,^g^,^l	X^f
Hymenarcys nervosa (Say)^a^,^c^,^d		X^f^,^g^,^j	Xⁿ
Mecidea major Sailer^a^,^c^,^e		X^j
Mormidea lugens (F.)^a^,^b^,^c^,^d^,^e		X^g^,^l
Murgantia histrionica (Hahn)^a^,^b^,^c^,^e	Harlequin bug		X^f
Neottiglossa undata (Say)^b^,^c^,^d^,^e		X^l
Oebalus pugnax (F.)^a^,^c^,^d^,^e	Rice stink bug	X^f^,^g^,^j^,^k	X^f^,ⁱ^,^j
Piezodorus guildinii (Westwood)^c	Redbanded stink bug	X^g^,^h^,^j^,^k
Proxys punctulatus (Palisot de Beauvois)^c		X^f^,^g
Thyanta calceata (Say)^c^,^d		X^f^,^g
Thyanta custator accerra McAtee^a^,^b^,^c^,^d^,^e	Redshouldered stink bug	X^f^,^g^,^j^,^k^,^l	X^f^,^j
Thyanta pallidovirens (Stål)^a		X^g

Scientific name	Common name	Soybean	Corn
Banasa dimidiata (Say)^a^,^b^,^c^,^d^,^e		X^g
Banasa euchlora Stål^a^,^b^,^c		X^g
Chinavia hilaris (Say)^a^,^b^,^c^,^d^,^e	Green stink bug	X^f^,^g^,^h^,^j^,^k^,^l	X^f^,^h^,ⁱ^,^j
Chinavia pensylvanica (Gmelin)^c^,^d^,^e		X^g
Chlorochroa persimilis Horvath^a^,^b^,^c^,^d^,^e		X^l	X^f^,^h^,ⁱ^,^j
Coenus delius (Say)^a^,^b^,^c^,^d^,^e		X^f^,^l
Cosmopepla lintneriana Kirkaldy^a^,^b^,^c^,^d^,^e		X^l	X^j
Euschistus ictericus (L.)^b^,^c^,^d^,^e		X^f^,^g^,^k^,^l	Xⁱ^,^o
Euschistus servus (Say)^a^,^b^,^c^,^d^,^e	Brown stink bug	X^f^,^g^,^h^,^j^,^k^,^l	X^f^,^h^,ⁱ^,^j^,^o
Euschistus tristigmus (Say)^a^,^b^,^c^,^d^,^e	Dusky stink bug	X^f^,^g^,^h^,^k^,^l	Xⁱ^,^o
Euschistus variolarius (Palisot de Beauvois)^a^,^b^,^c^,^d^,^e	Onespotted stink bug	X^f^,^g^,^h^,^j^,^l	X^f^,^g^,^o
Halyomorpha halys (Stål)^c^,^d^,^e	Brown marmorated stink bug	X^m	X^m
Holcostethus limbolarius (Stål)^a^,^b^,^c^,^d^,^e		X^f^,^g^,^l	X^f
Hymenarcys nervosa (Say)^a^,^c^,^d		X^f^,^g^,^j	Xⁿ
Mecidea major Sailer^a^,^c^,^e		X^j
Mormidea lugens (F.)^a^,^b^,^c^,^d^,^e		X^g^,^l
Murgantia histrionica (Hahn)^a^,^b^,^c^,^e	Harlequin bug		X^f
Neottiglossa undata (Say)^b^,^c^,^d^,^e		X^l
Oebalus pugnax (F.)^a^,^c^,^d^,^e	Rice stink bug	X^f^,^g^,^j^,^k	X^f^,ⁱ^,^j
Piezodorus guildinii (Westwood)^c	Redbanded stink bug	X^g^,^h^,^j^,^k
Proxys punctulatus (Palisot de Beauvois)^c		X^f^,^g
Thyanta calceata (Say)^c^,^d		X^f^,^g
Thyanta custator accerra McAtee^a^,^b^,^c^,^d^,^e	Redshouldered stink bug	X^f^,^g^,^j^,^k^,^l	X^f^,^j
Thyanta pallidovirens (Stål)^a		X^g

References for occurrence in midwestern United States:

a

b

c

d

e

References for crop associations:

f

McPherson (1982),

g

Panizzi and Slansky (1985),

h

McPherson and McPherson (2000),

i

Tillman (2010),

j

Suh et al. (2013),

k

Temple et al. (2013),

l

Koch and Pahs (2014),

m

Rice et al. (2014),

n

Sedlacek and Townsend (1988b),

o

Koch and Pahs (2015)

Table 1

Plant-feeding stink bugs potentially encountered in soybean and corn of the midwestern United States (“X” indicates reported presence of a species in a particular crop)

Scientific name	Common name	Soybean	Corn
Banasa dimidiata (Say)^a^,^b^,^c^,^d^,^e		X^g
Banasa euchlora Stål^a^,^b^,^c		X^g
Chinavia hilaris (Say)^a^,^b^,^c^,^d^,^e	Green stink bug	X^f^,^g^,^h^,^j^,^k^,^l	X^f^,^h^,ⁱ^,^j
Chinavia pensylvanica (Gmelin)^c^,^d^,^e		X^g
Chlorochroa persimilis Horvath^a^,^b^,^c^,^d^,^e		X^l	X^f^,^h^,ⁱ^,^j
Coenus delius (Say)^a^,^b^,^c^,^d^,^e		X^f^,^l
Cosmopepla lintneriana Kirkaldy^a^,^b^,^c^,^d^,^e		X^l	X^j
Euschistus ictericus (L.)^b^,^c^,^d^,^e		X^f^,^g^,^k^,^l	Xⁱ^,^o
Euschistus servus (Say)^a^,^b^,^c^,^d^,^e	Brown stink bug	X^f^,^g^,^h^,^j^,^k^,^l	X^f^,^h^,ⁱ^,^j^,^o
Euschistus tristigmus (Say)^a^,^b^,^c^,^d^,^e	Dusky stink bug	X^f^,^g^,^h^,^k^,^l	Xⁱ^,^o
Euschistus variolarius (Palisot de Beauvois)^a^,^b^,^c^,^d^,^e	Onespotted stink bug	X^f^,^g^,^h^,^j^,^l	X^f^,^g^,^o
Halyomorpha halys (Stål)^c^,^d^,^e	Brown marmorated stink bug	X^m	X^m
Holcostethus limbolarius (Stål)^a^,^b^,^c^,^d^,^e		X^f^,^g^,^l	X^f
Hymenarcys nervosa (Say)^a^,^c^,^d		X^f^,^g^,^j	Xⁿ
Mecidea major Sailer^a^,^c^,^e		X^j
Mormidea lugens (F.)^a^,^b^,^c^,^d^,^e		X^g^,^l
Murgantia histrionica (Hahn)^a^,^b^,^c^,^e	Harlequin bug		X^f
Neottiglossa undata (Say)^b^,^c^,^d^,^e		X^l
Oebalus pugnax (F.)^a^,^c^,^d^,^e	Rice stink bug	X^f^,^g^,^j^,^k	X^f^,ⁱ^,^j
Piezodorus guildinii (Westwood)^c	Redbanded stink bug	X^g^,^h^,^j^,^k
Proxys punctulatus (Palisot de Beauvois)^c		X^f^,^g
Thyanta calceata (Say)^c^,^d		X^f^,^g
Thyanta custator accerra McAtee^a^,^b^,^c^,^d^,^e	Redshouldered stink bug	X^f^,^g^,^j^,^k^,^l	X^f^,^j
Thyanta pallidovirens (Stål)^a		X^g

Scientific name	Common name	Soybean	Corn
Banasa dimidiata (Say)^a^,^b^,^c^,^d^,^e		X^g
Banasa euchlora Stål^a^,^b^,^c		X^g
Chinavia hilaris (Say)^a^,^b^,^c^,^d^,^e	Green stink bug	X^f^,^g^,^h^,^j^,^k^,^l	X^f^,^h^,ⁱ^,^j
Chinavia pensylvanica (Gmelin)^c^,^d^,^e		X^g
Chlorochroa persimilis Horvath^a^,^b^,^c^,^d^,^e		X^l	X^f^,^h^,ⁱ^,^j
Coenus delius (Say)^a^,^b^,^c^,^d^,^e		X^f^,^l
Cosmopepla lintneriana Kirkaldy^a^,^b^,^c^,^d^,^e		X^l	X^j
Euschistus ictericus (L.)^b^,^c^,^d^,^e		X^f^,^g^,^k^,^l	Xⁱ^,^o
Euschistus servus (Say)^a^,^b^,^c^,^d^,^e	Brown stink bug	X^f^,^g^,^h^,^j^,^k^,^l	X^f^,^h^,ⁱ^,^j^,^o
Euschistus tristigmus (Say)^a^,^b^,^c^,^d^,^e	Dusky stink bug	X^f^,^g^,^h^,^k^,^l	Xⁱ^,^o
Euschistus variolarius (Palisot de Beauvois)^a^,^b^,^c^,^d^,^e	Onespotted stink bug	X^f^,^g^,^h^,^j^,^l	X^f^,^g^,^o
Halyomorpha halys (Stål)^c^,^d^,^e	Brown marmorated stink bug	X^m	X^m
Holcostethus limbolarius (Stål)^a^,^b^,^c^,^d^,^e		X^f^,^g^,^l	X^f
Hymenarcys nervosa (Say)^a^,^c^,^d		X^f^,^g^,^j	Xⁿ
Mecidea major Sailer^a^,^c^,^e		X^j
Mormidea lugens (F.)^a^,^b^,^c^,^d^,^e		X^g^,^l
Murgantia histrionica (Hahn)^a^,^b^,^c^,^e	Harlequin bug		X^f
Neottiglossa undata (Say)^b^,^c^,^d^,^e		X^l
Oebalus pugnax (F.)^a^,^c^,^d^,^e	Rice stink bug	X^f^,^g^,^j^,^k	X^f^,ⁱ^,^j
Piezodorus guildinii (Westwood)^c	Redbanded stink bug	X^g^,^h^,^j^,^k
Proxys punctulatus (Palisot de Beauvois)^c		X^f^,^g
Thyanta calceata (Say)^c^,^d		X^f^,^g
Thyanta custator accerra McAtee^a^,^b^,^c^,^d^,^e	Redshouldered stink bug	X^f^,^g^,^j^,^k^,^l	X^f^,^j
Thyanta pallidovirens (Stål)^a		X^g

References for occurrence in midwestern United States:

a

b

c

d

e

References for crop associations:

f

McPherson (1982),

g

Panizzi and Slansky (1985),

h

McPherson and McPherson (2000),

i

Tillman (2010),

j

Suh et al. (2013),

k

Temple et al. (2013),

l

Koch and Pahs (2014),

m

Rice et al. (2014),

n

Sedlacek and Townsend (1988b),

o

Koch and Pahs (2015)

Among the species potentially encountered in soybean and corn in the midwestern United States (Table 1), several are encountered with frequency. Koch and Pahs (2014, 2015) and Koch and Rich (2015) recently performed surveys of the stink bugs associated with soybean and corn in Minnesota. In Minnesota soybean, E. variolarius, Euschistusservus euschistoides, and C. hilaris comprise 68–90% of stink bug adults (Koch and Pahs 2014, Koch and Rich 2015). In Minnesota corn, E. variolarius and E. servus euschistoides comprised 95–100% of stink bug adults (Koch and Pahs 2015). A predatory species, Podisus maculiventris (spined soldier bug) is also observed in corn and soybean (Koch and Pahs 2014, 2015; Koch and Rich 2015). Further work is needed to characterize the stink bug community associated with these crops in other states in the region. Understanding of stink bug anatomy (i.e., body parts) is important for identification of these species (Fig. 1).

Euschistus servus (Brown Stink Bug)

Euschistus servus occurs throughout the midwestern United States and much of North America (McPherson 1982), and is the most common species of Euschistus in the United States (Slater and Baranowski 1978). This species is composed of two subspecies (McPherson 1982). Euschistus servus euschistoides occurs in the northern United States (Fig. 2), and E. servus servus occurs in the southern United States. These two subspecies are known to interbreed and create a hybrid population, where their two populations meet in a swath extending from roughly Kansas to Maryland (McPherson 1982). These subspecies and the hybrid are similar in size (11.0–15.0 mm long; McPherson 1982) and color (brown or light brown). However, the subspecies can be distinguished from each other based on close examination of the head, antennae, and edge of the abdomen (i.e., connexivum). The tip of the head of E. servus euschistoides appears notched because the juga are longer than the tylus, whereas the tip of the head of E. servus servus does not appear notched, because the juga and tylus are equal or nearly equal in length (Paiero et al. 2013). In addition, the last two segments of the antennae (i.e., segments four and five) are usually dark brown in E. servus euschistoides and yellowish-brown or reddish-brown in E. servus servus (Paiero et al. 2013). Finally, the edge of the abdomen is completely or nearly completely covered by the front wing in E. servus euschistoides, whereas the edge of the abdomen is more exposed in E. servus servus (Paiero et al. 2013). Hybrid adults present a combination of the characters of the two subspecies (McPherson 1982).

Euschistus variolarius (Onespotted Stink Bug)

Euschistus variolarius occurs throughout the midwestern United States and much of North America (McPherson 1982). This is the most common stink bug in northern states, but it is relatively uncommon in the southern United States, particularly below 37° latitude (Parish 1934, Slater and Baranowski 1978). Adults of E. variolarius are yellowish-brown and 11.0–15.0 mm long (McPherson 1982, Panizzi et al. 2000; Fig. 2). Males have a large black spot on the underside near the tip of the abdomen (i.e., on the pygophore), hence the common name “onespotted stink bug” (Paiero et al. 2013). Euschistus variolarius and E. servus can be found in the same habitats at the same time (Koch and Pahs 2014, 2015) and look very similar to one another. However, E. variolarius can be fairly easily distinguished from E. servus euschistoides (i.e., the more common subspecies in much of the midwestern United States) by examination of the tip of the head and the “shoulders” (i.e., anterolateral margins of the pronotum; Fig. 2). The tip of the head of E. servus euschistoides appears notched, because the juga are longer than the tylus, whereas the tip of the head of E. variolarius does not appear notched, because the juga and tylus are equal or nearly equal in length (Paiero et al. 2013). The “shoulders” of E. variolarius are generally more pointed than those of E. servus euschistoides (McPherson 1982). Presence of the black spot on the pygophore of E. variolarius males is lacking in E. servus (McPherson 1982), but should not be confused with the black spots on the underside of the abdomen of a slightly smaller species, Euschistus tristigmus (Say).

A diagnostic key and descriptions of the nymphal instars of E. servus and E. variolarius are provided by Decoursey and Esselbaugh (1962) and Munyaneza and McPherson (1994). In general, nymphs of both species range from 1.5 to 10.4 mm long and are yellow brown in color (Fig. 3). First and second instars of the two species are nearly identical, but the later instars can be distinguished. Third to fifth instars E. variolarius have a white band on the under (i.e., ventral) side of the head that extends to or nearly to the eyes; however, this band is much reduced in E. servus (Munyaneza and McPherson 1994). In addition, the fourth and fifth instars differ in coloration of the last two (i.e., fourth and fifth) antennal segments, which are brownish-black in E. variolarius and red or reddish-brown in E. servus (Munyaneza and McPherson 1994; Fig. 3).

Fig. 3

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Stink bug nymphs (late-instars) encountered in soybean and corn of the midwestern United States: (A) Euschistus servus, (B) Podisus maculiventris, (C) Euschistus variolarius, (D) Thyanta custator, (E) Chinavia hilaris, and (F) Halyomorpha halys (photo credit: D. Pezzini).

Chinavia hilaris (Green Stink Bug)

Chinavia hilaris occurs throughout the midwestern United States and much of North America (McPherson 1982). This species is often referred to Acrosternum hilare (Say) (Kamminga et al. 2012). Adults of C. hilaris are green and 13.0–19.0 mm long (McPherson 1982, Panizzi et al. 2000; Fig. 2). However, an orange color form is infrequently encountered (Kamminga et al. 2012). In crops in the midwestern United States, C. hilaris is generally larger than the other green-colored stink bugs, such as Chlorochroa persimilis (11–15 mm) or T. custator accerra (see below; McPherson 1982, Rider 2012). Nymphs of C. hilaris are oval-shaped and range in size from 1.6 to 12.7 mm (DeCoursey and Esselbaugh 1962). Coloration of the nymphs transitions from mostly black with orange markings to mostly green with black and orange markings as nymphs develop (DeCoursey and Esselbaugh 1962; Fig. 3). However, as with the adults, the nymphs of C. hilaris present two different color forms (i.e., a light form and a dark form; Kamminga et al. 2012).

Thyanta custator accerra (Redshouldered Stink Bug)

Thyanta custator accerra occurs throughout the midwestern United States and large areas of North America (McPherson 1982, Rider and Chapin 1992). Adults of T. custator accerra are 9.0–13.0 mm long (McPherson 1982, Paiero et al. 2013; Fig. 2). Two color forms of this species exist; a green form in spring and summer, and a brown form in fall (McPherson 1982, Paiero et al. 2013). Some individuals of the green color form have a red- or pink-colored band across the pronotum, hence the common name “redshouldered stink bug” (Paiero et al. 2013). This species can be distinguished from P. guildinii, the redbanded stink bug, by the presence of a prominent spine extending from the base of the abdomen between the hind legs and pointing toward the head on P.guildinii, and the lack of such spine on T. custator accerra (Kamminga et al. 2009). A description of the nymphal instars of this species is provided by DeCoursey and Esselbaugh (1962). In general, nymphs range from 0.9 to 8.2 mm long (DeCoursey and Esselbaugh 1962). Coloration of the thorax and abdomen of nymphs transitions from brown with white and yellow markings to brown with white, amber, and yellow markings as nymphs progress from the first to fifth instars (DeCoursey and Esselbaugh 1962; Fig. 3). The third to fifth instars generally have a “T”-shaped mark on the pronotum (DeCoursey and Esselbaugh 1962).

Halyomorpha halys (Brown Marmorated Stink Bug)

Halyomorpha halys has rapidly spread throughout much of North America (Rice et al. 2014) and is becoming increasingly abundant in the midwestern United States. Adult H. halys are variable in color and size, but are generally 12.0–17.0 mm long with a marbled-brown coloration (Hoebeke and Carter 2003; Fig. 2), hence the common name the “brown marmorated stink bug.” Halyomorpha halys can be distinguished from other brown-colored stink bugs in the midwestern United States by its light colored underside, the presence of light-colored bands on dark antennae (i.e., the base and apex of the fourth antennal segment and the base of the fifth antennal segment are pale), alternating light–dark pattern on the exposed edges of abdomen (i.e., connexivum), and veins of the membranous parts of front wings are dark brown (Hoebeke and Carter 2003). A diagnostic key and description of the nymphal instars of H. halys is provided by Hoebeke and Carter (2003). In general, nymphs range from 2.4 to 12.0 mm long, and body shape changes from elliptical to pear-shaped as they develop (Hoebeke and Carter 2003). Coloration of the abdomen of nymphs transitions from yellowish-orange with black markings to mostly brown as nymphs progress from the first to fifth instars (Hoebeke and Carter 2003, Rice et al. 2014; Figs. 3 and 4).

Fig. 4

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Stink bug (H. halys) egg mass (A) and first-instar nymphs on hatched egg mass (B) (photo credit: D. Pezzini).

Podisusmaculiventris (Spined Soldier Bug)

Podisus maculiventris occurs throughout the midwestern United States and much of North America (McPherson 1982), and is the most common predatory stink bug in much of the United States (Slater and Baranowski 1978, De Clerq 2000). Adults of P. maculiventris are brown and 8.5–13.0 mm long (Slater and Baranowski 1978, McPherson 1982; Fig. 2). The “shoulders” (i.e., anterolateral margins of the pronotum) of P. maculiventris are pointed (McPherson 1982), hence the common name “spined soldier bug.” These pointed “shoulders” may cause confusion between this species and some of the common herbivorous species such as E. variolarius. The thickness of the mouth parts (i.e., rostrum) can be used to distinguish P. maculiventris and other predatory stink bugs (Asopinae) from herbivorous stink bugs (Pentatominae; Paiero et al. 2013). The rostrum of the predatory species is thick (about twice the thickness of the antenna) and that of the herbivorous species is thin (similar to thickness of antenna; Fig. 5). Nymphs of P.maculiventris range from 1.15 to 8.6 mm long, and body shape changes from broadly oval to elongate oval as they develop (DeCoursey and Esselbaugh 1962). Coloration of the nymphs transitions from red with black markings to tan or orange with red and white markings as nymphs progress from the first to fifth instars (DeCoursey and Esselbaugh 1962, Evans 1985; Fig. 3). Nymphs of P. maculiventris can be distinguished from other Podisus spp. using a diagnostic key by Evans (1985).

Fig. 5

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Mouthparts (i.e., rostra) of predatory (A) and herbivorous (B) stink bugs. Rostrum of predator is thick (about twice the thickness of the antenna), and rostrum of herbivore is thin (similar to thickness of antenna) (arrows indicate rostra and antennae; photo credit: D. Pezzini).