Metallus rohweri
MacGillivray, 1909
Metallus rohweri is a in the Tenthredinidae, first described by MacGillivray in 1909. It belongs to the Blennocampinae and is one of approximately five in the Metallus. The genus is characterized by metallic coloration and association with Rubus plants. This species is known from northeastern North America.
Pronunciation
How to pronounce Metallus rohweri: //məˈtæləs ˈroʊwɛraɪ//
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Identification
Metallus rohweri can be distinguished from by geographic range and subtle morphological differences. The Metallus is characterized by metallic blue or green coloration, a relatively broad , and with 9 segments. Specific characters separating M. rohweri from the European M. lanceolatus and other North American require examination of genitalia and wing venation patterns. are small to medium-sized , approximately 5-7 mm in length.
Images
Habitat
Associated with Rubus , particularly raspberry and blackberry. Occurs in open , forest edges, and areas where plants grow.
Distribution
Northeastern North America: recorded from Ontario, Quebec, Nova Scotia (Canada), and Vermont (United States).
Seasonality
have been observed from May through July, with peak activity in June. Larval feeding occurs during summer months.
Diet
Larvae feed internally in stems of Rubus (raspberry and blackberry), creating galls or tunneling in pith tissue. do not feed.
Host Associations
- Rubus - larval stem borer
Life Cycle
Females insert into Rubus stems. Larvae develop within stems, feeding on pith tissue and creating gall-like swellings or internal tunnels. occurs in soil or within the stem. One per year.
Behavior
Larvae are concealed feeders within plant stems. are active during daylight hours and have been observed visiting flowers.
Ecological Role
As a stem-boring herbivore, contributes to natural pruning and nutrient cycling in Rubus . May affect commercial raspberry and blackberry production.
Human Relevance
Occasional pest of cultivated raspberries and blackberries. Larval tunneling can weaken canes and reduce fruit production. Generally considered a minor pest with limited economic impact.
Similar Taxa
- Metallus lanceolatusEuropean with similar and ; distinguished by geographic range and subtle genitalic differences
- Metallus pumilusNorth American with overlapping range; requires examination of male genitalia and proportions for reliable separation
- Metallus abdominalisNorth American ; differences in abdominal coloration and wing venation aid identification
More Details
Taxonomic history
The Metallus was historically placed in the Cephidae by some authors due to superficial similarities in body form, but is now firmly established in Tenthredinidae based on larval and molecular data.
Larval damage
Infested Rubus canes show swollen nodes or irregular swellings where larvae have fed. Affected canes may break easily or produce reduced fruit the following year.