Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
Option 1 | Option 2 |
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Anal prolegs each with basal half broadly joined with segment 9, its anal claw with at least one dorsal accessory hook (sf 19.59, 19.60) | Anal prolegs mostly free from segment 9, its anal claw without dorsal accessory hook, although secondary lateral claw may be present (sf 19.57) |
Larvae construct tortoise-like domed portable cases of rock fragments (sf 19.38, 19.167, more) | Larvae free-living, without cases or fixed retreats until pupation |
Remaining families: Hydrobiosidae and Rhyacophilidae | |
1 Example SpecimenI caught this tiny larva without a case, but it seems to key pretty clearly to to Glossosomatidae. From there, the lack of sclerites on the mesonotum points to either Glossosoma or Anagapetus. Although it's difficult to see in a 2D image from the microscope, it's pretty clear in the live 3D view that the pronotum is only excised about 1/3 of its length to accommodate the forecoxa, not 2/3, which points to Glossosoma at Couplet 5 of the Key to Genera of Glossosomatidae Larvae.
| 5 Example Specimens |
Glossosomatidae | Go to Couplet 10 |