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Montana Field Guide

Montana Field Guides

Stevenson's Shieldback Katydid - Pediodectes stevensoni

Native Species

Global Rank: GNR
State Rank: SNR

Agency Status


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General Description
The following comes from Caudell (1907), Hebard (1928), and Vickery and Kevan (1985). The head is of moderate size. The pronotum (thorax) is large and moderately elongated and without carinae (ridges), but some individuals may possess traces on the posterior portion where the disk may be somewhat flattened. The lateral lobes are well developed. The front of the sternum (prosternum) possesses a pair of variable spines, which can be short and blunt or long and sharp. The wings of the female are generally hidden under the pronotum. Male wings usually extend beyond the pronotum about one-third, or less, its length. The hind femur is more than two times as long as the pronotum and much enlarged at its base. The front tibia possess three spines, sometimes four.

Note on the genera Pediodectes and Steiroxys
These two genera have never been studied in detail. Some of the other eight known species presently recognized may not be valid and others may still be awaiting discovery. This lack of study remains as current today as it did at the turn of the 20th century. In the early literature, the genus of this species was Stipator (Caudell 1907).

Calling song description
No verbal song descriptions are found in the literature for this species. However, the writer of this description offers the following based upon personal observations, recordings, and the audio from Walker (2020), “A series of faint, raspy chirps about every 2 seconds” (Scott personal field note entry, August 28, 2011).

To date, no studies nor observations have been found within the published literature. Possibly similar to other Shieldbacks in their adult stage.

Diagnostic Characteristics
The length of the male pronotum is 5-6.5 mm, and for females, 5-7 mm. The male hind femur length is 16-18 mm, and for females 15-21 mm. The ovipositor is 14-18 mm (Caudell 1907).

The Stevenson’s Shieldback can be confused and misidentified with the Grass Shieldback (Steiroxys trilineatus), but unlikely with other Shieldbacked species, such as Anabrus and Peranabrus.

Species Range
Montana Range Range Descriptions


Range Comments
This species’ occurs from south-central Montana and southern South Dakota, southward to Texas; east of the Rocky Mountain Range, eastward to Nebraska. In Montana, it has been reported in 3 counties (Vickery and Kevan 1985, Scott 2010, and Walker SINA website 2020).

No studies have been reported in the literature relative to this species’ preferred habitat. The most recent collection of two specimens (both females) were made in Billings, Yellowstone County, in late August 2011 at two separate locations. One habitat was a grassy area amid a sagebrush-juniper community, the second area amid snowberry, Symphoricarpos sp. with mixed grasses in an Eastern cottonwood (Populus deltoides), riparian woodland (Scott 2010, map only [live specimens collected, photographed, and habitat noted post-publication]).

Food Habits
Stevenson’s Shieldback is thought to be both herbivorous and carnivorous. Otherwise, no specific food habits are presently known (Caudell 1907).

Reproductive Characteristics
To date, no studies nor observations have been found within the published literature.

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Citation for data on this website:
Stevenson's Shieldback Katydid — Pediodectes stevensoni.  Montana Field Guide.  .  Retrieved on , from