|Melanoplus bivittatus |
common name Twostriped grasshopper
The twostriped grasshopperinhabits areas with lush vegetation across North America. It is abundant in tallgrass prairies, wet meadows, roadsides, and crop edges (Pfadt 2002).
Melanoplusbivittatus nymphs (no wings or short wing buds) hatch from egg pods in the soil early in the summer and are one of the first species to appear. They continue to hatch for four to six weeks following rain and warm temperatures and so may be found in an area up to 75 days. Adults (wings extend the length of the abdomen) can be found 40 days after the nymphs have emerged (Pfadt 2002). In Alberta they have been found from May to September (Strickland Museum records).
The twostriped grasshopper is one of the two largest in the genus Melanoplus grasshoppers, the other being Melanoplus differentialis which is found in the same habitat in the United States. This and other grasshoppers of the subfamily Melanoplinae often have a spiny bump on their "throat" between their front legs (Johnson 2002). Adult males of this species are easily identified by their mitten-shaped cerci. Both males and females have a pair of distinctive yellow stripes that run down their body, head to mid-wing, where they meet to form a triangle (Pfadt 2002).
The life cycle of this species is described in Pfadt's Field Guide to Common Western Grasshoppers (2002). Nymphs mature through 5 instars before emerging as an adult in the first part of summer. Most populations have a one-year life cycle, but some mountainous populations are known to have a two-year life cycle. Females deposit their eggs in crowns of grass or roots of weeds, often along south-facing roadsides, one or two weeks after mating. The egg pods are curved tubes up to 4 cm long and may contain 50 to 108 olive-coloured eggs. The eggs complete the majority of their development that summer before going into diapause for the winter, allowing them to hatch early the following spring.
The twostriped grasshopper is a serious agricultural pest to grain crops, alfalfa, and corn. During outbreaks it will completely defoliate crops and even in urban areas it will devour flowers and vegetables (Pfadt 2002).
This species feeds on a broad variety of plants, both forbs and grasses. These include mustards, alfalfa clover, greenflower, dandelion, chicory, prickly lettuce, ragweed, prairie sunflower, perennial sowthistle, and kochia (Pfadt 2002).
This species is wide spreadfrom coast to coast across North America, as far north as northern British Columbia, Alberta, Saskatchewan, Manitoba, the majority of Ontario, the southern part of Quebec, and most of the maritime provinces. Its range extends south throughout the entire United States except for the few states bordering the Gulf of Mexico (based on range map in Pfadt 2002). They have been collected in mid and southern Alberta (Strickland Museum records).
Both the nymph and adult forms of Melanoplusbivittatus are migratory (Pfadt 2002). At high densities the nymphs form bands and move out when the temperatures are 24° C or higher. The adults migrate by flying with the wind when the day has warmed up to 30° C and can reach heights of 180-430m allowing them to disperse far distances.
These grasshoppers spend the night perched on tall vegetation that they climb in the evening before the sun sets (Pfadt 2002). Early in the morning, after sunrise, they climb down and may bask in the sun or begin to feed and migrate (Pfadt 2002).
|species page author||Bird, H.||2010 |