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Song data:
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Excel worksheet and chart (from spectrographic analyses).
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Identification:
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LENGTH:
LENGTH As used in descriptions of whole insects on this site, length was measured with dial calipers from the head of the specimen to the tips of the forewings (at rest) or to the tip of the abdomen, whichever was longest. In females, the measurement excluded the ovipositor but included the subgenital plate. In males, the measurement included any ventral or dorsal abdominal process.
13–18 mm. Members of the nigricornis species group can be challenging to differentiate. Oecanthus forbesi can be differentiated from some other members of the nigricornis species group by its dark ventral abdomen. O. celerinictus, O. quadripunctatus, O. salvii, and O. walkeri lack any dark coloring on the ventral abdomen. While O. argentinus can have darkened areas on the ventral or lateral/ abdomen, and O. forbesi can have antennal markings as thick as those of O. argentinus, the male song pulse rate/frequency ratio differs. Both O. forbesi and O. nigricornis can be completely green, have a yellowish tinted head, have some black, or have a great deal of black, therefore it is impossible to separate them based on appearance. Past recordings have led to a general understanding that O. forbesi is found west of Ohio, O. nigricornis is found east of Ohio, and both species can be found in Ohio.
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Similar species:
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The coloring and antennal markings of O. forbesi, O. nigricornis and O. argentinus can be identical in some cases. O. forbesi and O. nigricornis are impossible to separate morphologically, as both species vary from all green to having large amounts of black. In order to determine O. forbesi vs O. nigricornis, one needs to compare the male song pulses per second and frequency at a measured air temperature at the spot where the tree cricket is singing. At 25°C, O. forbesi (fast-trilling) = 65 pulses per second / 3.8 kHz, and O. nigricornis (slow-trilling) = 50 pulses per second / 4.0 kHz (Walker 1963).
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Habitat:
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Generally found less than six feet above the ground on plants and shrubs. Not known to dwell high in trees. Found on a wide variety of plants, too numerous to list, but includes: goldenrod, Queen Anne’s lace, asters, thistles, Joe Pye weed, coneflower, raspberry, and dogwood.
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Season:
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One generation per year with eggs laid September through November, and nymphs emerging May through August.
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Remarks:
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Forbes’, Black-horned, and Prairie cannot be reliably identified to species by appearance alone.
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More information:
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Genus Oecanthus, subfamily Oecanthinae.
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References:
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Fulton 1926a; Titus 1903; Walker 1963. Collins 2010-date.
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Nomenclature:
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OSF (Orthoptera Species File Online)
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