Compare Insect Features and Choose Montana Identification Resources

Common Montana insects: a practical starting point

Montana's insect fauna is far too large for a single list. Grasshoppers are a useful starting point for anyone watching prairie and grassland edges, because they are conspicuous and well documented. The state's official species accounts include two widespread examples. The Two-striped Grasshopper is reported as common in all 56 Montana counties. The Differential Grasshopper is recorded from 17 counties and is considered probably widespread in eastern Montana. For other groups, such as bumble bees, dragonflies and damselflies, butterflies and moths, beetles, flies and aquatic insects, Montana has group-specific references and collection projects, described below.

Two documented grasshoppers compared

Both species belong to the same genus, Melanoplus, in the short-horned grasshopper family Acrididae (order Orthoptera). Because they are close relatives, general body shape will not separate them. The markings on the back and on the outer face of the large hind leg segment, the hind femur, are what matter.

Feature	Two-striped Grasshopper (Melanoplus bivittatus)	Differential Grasshopper (Melanoplus differentialis)
Key back marking	Two pale-yellow stripes run from behind the eyes toward the forewing tips and converge into a V	No paired-stripe character is given as diagnostic
Outer hind femur	Dark upper stripe over a yellow lower portion	Black chevrons (V-shaped marks); this is the distinguishing character
Color variation	Not noted as a key issue in the account	Nearly black forms also occur
Reported Montana range	Common; recorded in all 56 counties	Recorded in 17 counties; probably widespread in eastern Montana
Habitats described	Lush vegetation, roadsides, field margins	Wet meadows, swales, creek bottoms, weedy roadsides and crop margins

In short, check the back for paired pale stripes forming a V, then check the hind femur for a dark-over-yellow stripe pattern versus black chevrons. A nearly black Differential Grasshopper can hide the chevron pattern, so a dark individual should not be named on color alone.

Habitat relevance on the prairie

Neither account frames these species as specialists of intact native grassland. Both are tied to lush or disturbed vegetation. The Two-striped Grasshopper is described from roadsides and field margins. The Differential Grasshopper favors moist low ground, such as wet meadows, swales and creek bottoms, as well as weedy edges of roads and crops. The University of Wyoming's western grasshopper guide likewise lists both under tallgrass prairie and disturbed land. That listing does not establish that either species is found in local mixed-grass prairie.

For an observer in northeastern Montana, these species are reasonable candidates along field edges, ditches and damp low spots. Statewide or county-level occurrence still does not document a sighting at a specific site such as Medicine Lake. Record exactly where and in what habitat each insect was seen.

Adults versus nymphs

Young grasshoppers (nymphs) are harder to identify than adults because their wings and genital structures are not fully developed. The Wyoming guide addresses this with separate nymph and adult photographs, diagnostic illustrations, distribution maps and habitat accounts. If the insect is small and short-winged, compare it against the nymph images rather than adult descriptions.

Choosing an identification resource

Pick references by two criteria: the geography they cover and the insect group they cover. A regional grasshopper guide can resolve stage-specific details that a statewide species account does not, while the state account is the better source for Montana range.

Resource	Geographic scope	Taxonomic scope	Best use
Montana Field Guide	Montana	Statewide species accounts, including insects	Search by common or scientific name or browse taxonomically. Accounts separate general description, distinguishing characters, range and habitat. Browsing groups can be exported as PDFs, and Advanced Search includes a custom PDF Creator.
University of Wyoming western grasshopper field guide	Western grasslands	Grasshoppers	Compare nymphs and adults with photographs, diagnostic illustrations, distribution maps and habitat tables.
Montana Natural Heritage Program identification-resource directory	Montana	Multiple groups	Find group-specific references such as Bumble Bees of Montana, western dragonfly and damselfly guides, and BAMONA (Butterflies and Moths of North America) tools. The program's Species Snapshot filters by area, taxonomic group and status.
Montana Entomology Collection	Northern Great Plains and Rocky Mountains	Strengths in aquatic insects, beetles, flies and bees	Look into regional collection projects, including Montana bee and aquatic-invertebrate work.

A workable sequence is to start with the Montana Field Guide for state range and habitat, then turn to the Wyoming guide for grasshopper comparisons by life stage. For bees, dragonflies, butterflies and other groups, use the Natural Heritage Program directory or the collection's projects. Note each reference's region, taxonomic scope and the diagnostic passage you relied on.

Recording an observation before naming it

Write down what you saw before you propose a name. This keeps the description from bending to fit the first guess. A simple worksheet layout:

Observation ID:
Date:
Location and habitat:
Photograph references:
Visible markings:
Body outline:
Appendages (legs, wings, antennae):
Obscured features:
Proposed name:
Diagnostic passage used:
Montana range evidence:

When a feature can't be seen

Hypothetical example: photograph A shows paired pale stripes on the back, and photograph B shows chevrons on the hind femur. Compare each image against the matching diagnostic account and against the other visible characters as well. If the hind leg in photo A is hidden, the stripes point toward the Two-striped Grasshopper, but the femur pattern remains unconfirmed. If the back in photo B is out of view, treat the identification the same way.

Never treat an unseen feature as absent. When the diagnostic part is obscured, the insect is a nymph, or the specimen is a dark form, record the identification as unresolved, for example "Melanoplus sp." Try to photograph the back and the outer hind leg on the next encounter.