Amphitornus
McNeill, 1897
slant-faced grasshoppers
Amphitornus is a of slant-faced in the , Gomphocerinae, tribe Eritettigini. The genus contains at least two described : Amphitornus coloradus (striped slant- grasshopper) and Amphitornus durangus. Members of this genus are recognized as economically significant rangeland pests in the western United States, particularly in Wyoming and Colorado. Amphitornus coloradus is specifically noted as one of six major in southeastern Wyoming and is characterized by early-season hatching in mid-spring.
Pronunciation
How to pronounce Amphitornus: /æmˈfɪtɔrnəs/
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Identification
Amphitornus belongs to the slant-faced group ( Gomphocerinae), distinguished by a that slants backward toward the body rather than perpendicular to the body axis. This separates it from -throated grasshoppers (Melanoplinae), which have a conical spur between the legs and a perpendicular face, and from (Oedipodinae), which have a perpendicular face but lack the spur. Within Gomphocerinae, -level identification requires examination of specific morphological features; A. coloradus is commonly known as the striped slant-face grasshopper. of slant-faced grasshoppers are typically , slender, and active.
Images
Habitat
Rangeland and grassland in the western United States. in this are associated with open, dry grassland environments typical of the high plains and intermountain regions.
Distribution
Western United States including Wyoming, Colorado, Montana, Arizona, California, and Illinois. The has also been recorded from Durango, Mexico ( locality of A. durangus).
Seasonality
Early hatching group; emerge in mid-spring. are present during the summer months. This early-season distinguishes Amphitornus coloradus from intermediate and late-hatching in the same region.
Life Cycle
Overwinters as in . Eggs hatch in mid-spring when soil temperatures reach approximately 50–55°F. progress through five over 30–50 days under favorable conditions, molting periodically as develop. appear in summer and females in soil after a one-to-two week pre-reproductive period.
Ecological Role
As a rangeland , contributes to forage consumption in grassland . Can reach that significantly reduce available forage for livestock.
Human Relevance
Amphitornus coloradus is recognized as a major economic pest of rangeland in southeastern Wyoming and surrounding regions. It is one of six primary targeted in cooperative management programs. The is notably to using applied in bran , and shows low mortality (4% in laboratory, 0% in field) from carbaryl-treated bran baits, making chemical control challenging. Grasshopper management guidelines specifically note that bran bait applications have little or no effect on this species.
Similar Taxa
- Ageneotettix deorumAlso a slant-faced (Gomphocerinae) and major rangeland pest in the same region; distinguished by specific morphological features and (whitewhiskered grasshopper)
- Aulocara elliottiAnother slant-faced rangeland pest in the same region; known as the bigheaded
- Cordillacris occipitalisSlant-faced and co- pest in southeastern Wyoming ; known as the spottedwing grasshopper
- Melanoplus bivittatusMajor in same region but belongs to -throated group (Melanoplinae); distinguished by perpendicular and presence of spur between legs
- Melanoplus sanguinipesMajor pest in same region but -throated; known as the