MC: This flatworm is different from those I've found downstream -- it lacks the pointed head and large eyespots. You mentioned in a previous email that this type actually has eyespots, it's just that they are small and arranged in a row across the front of the head. Even though I have encountered flatworms with some regularity, they sometimes don't show up on the Pollution Tolerance Index (order-level) as a species for consideration. Do they have a significant role in water quality assessment, or does their presence merely add to the species diversity?

JA: They don't have a huge role in water quality assessment, but can sometimes be very abundant. Typically in degraded environments, but I seem to remember seeing them in large numbers in some really cold, clean water. Not sure what the favorable conditions are for them, probably rocky substrate and lots of detritus.

MC: As predator/collectors, what types of things are they likely to prey upon and what sorts of things do they collect?

JA: I've always been a bit fuzzy on their feeding habits and which species feed in which manner or if they're all opportunistic. I've often seen them preserved with their proboscis shoved into a small minnow or prong gill mayfly that's nearly as big as they are. I assume that's an example of the predation and not just some wierd artifact of sample collection. As collectors, they're feeding on fine organic debris or detritus

MC: It's been interesting to photograph the differences in mites this year. Because they are so small, they really need to be magnified in order to see and appreciate the variety. (Unfortunately, they also don't stay still very well -- urgh!) Your guide indicates that the mites are "predator/scavengers." Is there some way to tell the difference between predators and scavengers, or are they all pretty much predators & scavengers. If I remember correctly, I've also read that some of them are also parasites.

JA: I'm pretty sure all of them are parasites. ... Does that throw you? :) Actually, once you have the 8-legged mites you're taking pictures of they're mostly predators/scavengers, but all of them have a 6-legged larval stage that is parasitic. Once in a while, if you're looking close, you'll see the small, white, parasitic larvae attached to soft parts of other invertebrates. As for the adults, like the ones you have pictured... I'm not sure if it always holds true, but the large, thick palps at the front of their head are great for grasping prey. Based on that, I would say the first mite you have pictured is a predator, while the other two are scavengers.

MC: There have been some samples with large numbers of mites. If they are all counted (difficult process because they are so small, and easily overlooked by students) they can really affect some of the index calculations. How much influence should they have in the results? I mean, it seems strange that a little mite counts the same as a giant stonefly.

JA: An unfortunate fact of bimonitoring is that once in a while, you just have a "bloom taxa" that screws up your sample beyond usefulness. Flat headed mayflies and black flies are frequent culprets. Mites can also be very abundant. Disproportionate abundance usually indicates something is out of balance in the system, but sometimes it just happens. I would hazard to guess that when you find a lot of mites, all or part of your sample was collected in a spot that had lots of organic debris and detritus for them to sort through... maybe a stream margin or slower part of the stream.

MC: Small crayfish -- no branchiobdellid worms seen this fall.

JA: Just a baby! Probably native though. We found a new population of introduced crayfish in the John Day River this year, which means they have full access to the entire Columbia Basin. Before they were limited to the Rogue River Basin.

MC: The beetles are another group of macros that require magnification to appreciate. They tend to show up quite regularly in our samples -- if you have the patience to look for them.

JA: They are very common and pretty diverse, but as you note, they're small, slow, brown, and generally cryptic. If you're sorting live in the field, I can see the justification in leaving them out, but they're included in most biomonitoring studies.

MC: The Pollution Tolerance Index (PTI) that we've used has the adult beetles and riffle beetle larva listed separately, with different tolerance values.

JA: That's odd. The adults and larvae may have different food preferences (though I think they're mostly collectors-gatherers as larvae and as adults), but they should have the same tolerance because they live in exactly the same habitat. If it doesn't support adults, you certainly aren't going to find larvae there.

MC: Are there differences between beetles that we should be aware of that indicate significant differences in water quality? I remembered looking at your CD and trying to figure out some of the different taxa. Most noticeably, some larva have a raised ridge running down the length of the body, while others are rounded.

JA: It's not unusual to find 5 genera of riffle beetle in a healthy stream (they don't like super cold water though). There are some that are more tolerant, but telling the difference between adults and between some of the larvae can be very difficult.

• First, the easy larvae... long and gold with lots of spikes on its head - relatively sensitive Narpus
• broad, hairy, thick, and sometimes large, with a ridge down each side and two ridges down the middle - Lara, a wood shredder, has a different feeding habit than any of the others
• the others are pretty similar with some triangular in cross-section and some rounded

MC: Was I correct in labeling all of those as riffle beetles (larva & adults). Obviously, the predaceous beetle [below] is different.

JA: Easy adult...- image 54 and 68 both have Zaitzevia. It's skinnier than most of the others, usually solid reddish-brown with darker front end, and the antennae are tightly coiled and depressed against the head so that you won't see them. The rest of the adults may have different light-dark patterns on their hard wings (elytra) and may have slightly different shapes (more rounded body or longer legs), but most are pretty tough to distinguish. I'll let you know if I see any unusual ones. The other adult you have pictured here is probably Optioservus. Optioservus and Zaitzevia are probably the most common riffle beetles and should be found in almost every stream.

MC: Should predaceous beetles be counted with the riffle beetles when doing order-/family-level sampling?

JA: When doing Order-level, I guess so, but they're in a different family. The larvae of predaceous beetles are benthic (live on the substrate), but the adults are swimmers and not technically part of the benthic macroinvertebrate community that is targeted in standard sampling. Thus the adults are usually kicked out. I'd probably keep them for your students though, because they're interesting critters.

MC: I'm not sure if there are 2 or more different golden stoneflies. The fourth one (#15) is obviously different from the first three. The coloration, patterns, and shape of the thoracic plates cause me to think that the first one is different from the second and third. I'm not sure, however, if I'm reading too much into these differences.

JA: You probably have two golden stones that should show up in any healthy low-mid elevation stream. The 4th (Hesperoperla) has gills between its tails, is usually black with a few light marks and a light hourglass on top of its head. The first three are probably all Calineuria, though a cold-water genus looks very similar but has a mohawk down the middle of its entire body (most notable in the mature larvae). The color pattern differences are probably due to being closer or farther from molting.

MC: I found more of the yellow stoneflies with the finger-like gills between the legs. They tend to throw people off when we describe goldens as having "hairy armpits" and yellows not having visible gills between the legs. I just remind them that there are always exceptions to the rule -- especially in nature.

JA: The rule holds if you consider "hairy" as lots of hairs. The yellow stones won't have more than two gills between any legs. In fact, your students collected Perlinodes which has about the longest, most obvious gills of any of the yellows found around here and also has the two pairs of long gills under its head.

MC: I've started finding more little browns. (Maybe I've just become more aware of them.) I liked the way this one photographed. I found some others downstream that appear more "fuzzy" -- these will be in the next set of images I post for Lewisville Park.

JA: That is a nice picture. You can even see the gills pretty well under the neck. It's probably Malenka. They are quite common and seem to mature a little earlier than the even more common Zapada. The one you have a picture of has nice big wing pads, showing that it's mature. Zapada tend not to have large wingpads until later in the year. The whole family is known for being hairy. The genus Visoka probably takes the cake, but is only found at higher elevations in colder streams.

MC: I finally found some giant stoneflies in the East Fork! I found them in several samples in the upper East Fork, which makes me think they are relatively common. Additionaly, I saw my first one at Lewisville this fall -- there was only one, however. They are either not as abundant downstream or we are not looking it the right places (the lower East Fork is a much larger stream). How diverse is this group of stoneflies? Am I likely to find more than one taxa?

JA: There are two genera and about 5 species. The truly giant genus is Pteronarcys which you most definitely have in the latter two images. The species of that one is probably Pteronarcys princeps because the plate on top of the first thoracic segment has fairly rounded corners. Pteronarcys californica has long, sharp points on those corners when its mature. The other genus is Pteronarcella. It's more common in lowlands and never gets very big. It's possible the first picture is of that genus, but it could also just be an immature Pteronarcys. Easy to tell the two genera apart though. Pteronarcys will have gills on the underside of the first two abdominal segments (as you have in your picture). Pteronarcella will have them on the first three abdominal segments.

MC: I was also excited to find a roach-like stonefly in the East Fork. I saw my first ones this summer on a trip with Patrick Edwards. [Part of a grant-funded workshop for educators, taught by Patrick Edwards of Portland State University, to the Andrews Experimental Forest in Oregon]. This was the only one I found in the East Fork, however.

JA: They're moss-o-philes, so if you really wanted to find them, tear some moss off rocks in the stream. Then again, better not do that, because moss is a very sensitive habitat. You'll find more of them though. Most are of the genus Yoraperla, though there is [a] species of concern in the genus Soliperla that's found not too far to the east of you.

MC: I find this dark spiny crawler with the light stripe with some regularity. Occassionally, I find the spiny crawlers that are reddish.

JA: The stripe usually means Seratella, but Seratella and Ephemerella and all the species in them are tough to tell apart.

MC: I found quite a few of the small (3-5 mm) Drunella. I haven't found any that are near the size of the one I found last spring (15 mm). Do they mature in the spring and early summer?

JA: Sounds like you've got your own evidence for spring emergence. Good call. There is also some variation in emergence between species, water temperatures, and other cues.

MC: I was curious about this pebbled case I found attached to a rock. When I peeled it open, I found a yellow pupa inside. The nearest I can tell (based on a couple of illustrations I found in books), it looks like a netspinner pupa. But I haven't seen any netspinners that are yellow, or that have the row of black hairs on the lower abdomen. (The hairs are more apparent in a pupa I found at Lewisville -- which I have in the set of images for the East Fork, Fall 2005.) Pebbly cases attached to rocks seem pretty abundant in places, although, some of the cases we examined later in the fall were empty.

JA: The net spinners can be yellow, but based on the case and size (and assuming the case was pretty solid), I would guess it's a uenoid case maker (they don't really have a common name). They're pretty common and carry their cases around on their back. They often place a larger pebble on each side of the head-end of their case.

MC: Couple of different free-living caddisflies.

JA: Probably the two most common free-living caddisflies. Nice pictures. The pupa, however, is probably a third, less common species.

MC: Found my first biting midge in the East Fork -- difficult to spot in a sample of debris.

JA: And I have no idea how you got it to slow down enough for a picture. They're often quite active wigglers.

MC: The fly pupae are the first I've observed. I had seen small illustrations, but never seen them in real life. It was interesting to collect these three. The first two are similar, but the third is quite different. Are they all black fly? Also, if you look at the magnified view of the yellow pupa, it looks like it has a monkey face. Interesting?!

JA: The first two are pupae of the crane fly Antocha. It's a common crane fly, and pretty distinctive. I didn't see a picture of a larva in your catalog, but you'll probably catch one one of these days. It's a wild looking pupa to be sure. The third one is certainly a black-fly pupa. They're common and all look just about the same (short, squat, with gills out the front, and are usually in a silk sleeve).

MC: Finally, three cranefly larva. My students' refer to these as the "UGLY" looking macros. Is there a name for the two fleshy protrusions at the posterior end of the first image? Also, is that its mouth part protruding from the front of its body? Finally, you list the craneflies as predators/shredders. Is there a way to tell the difference? Does having prolegs make a difference? If we attempt to do a feeding groups analysis, it might be helpful to make the distinction.

JA: They are quite maggoty. The fleshy protrusions are just called lobes but are very useful in identification because there are different numbers of them (from 1 to 7) and have different color and hair patterns. You might have three genera pictured. The first with the prolegs is Dicranota - very common, and [you] caught it with it's head remarkably extended. As a predator, it can fire that head out from inside its body and grab prey. The second is Hexatoma, and you can barely see its large maxillae sticking out of the front end (giving it a slightly squared off shape). Whenever you see those, you can be pretty confident that it's a predator. The third one is tough to tell. It could be a Hexatoma, but there are dozens of different kinds of crane flies. Again, those maxillae are the best indication of predator vs. shredder. They're usually obvious in Hexatoma, but less so in some of the other predators, like Dicranota.

Hope that helps; keep up the great work! JEff

Once again, we'd like to thank Jeff Adams, Director of Aquatic Programs for The Xerces Society, for taking the time to look at and comment on the macroinertebrate images above. As author of the CD-ROM, The Stream Bugs as Biomonitors: Guide to Pacific Northwest Macroinvertebrate Monitoring and Identification, he has considerable knowledge in identifying aquatic macroinvertebrates and experience in using "stream bugs" as bio-indicators of water quality. If you'd like to hear more from Jeff about macroinvertebrates, check out a scaled down Internet version of The Stream Bugs as Biomonitors... CD-ROM at The Xerces Society website. Better yet, order a copy for yourself. (PC compatible only; many images won't show on a Macintosh)

Additional image sets with comments from Jeff Adams: East Fork Lewis River at Lewisville Park - Spring 2005 | Upper East Fork Lewis River - Fall 2005 | Salmon Creek - Dec. 2005 | Lacamas Creek - Nov. 2005