This idea has been brought up in the midst of another topic, so I thought I would present it separately to keep it from getting buried:
In the field of academic publishing, the practice is for the authors of publications or researchers (even anthropologists or linguists) to have specimens collected and preserved of any organisms whose identity is significant to the data in question. These are called "voucher specimens", presumably because they would "vouch for" the accuracy of the identifications used in the publication or research.
Why should we do this at BugGuide?
First of all, there are numerous taxonomic groups in BugGuide that are difficult or impossible to identify completely from images. It has been observed that details of genitalia reflect taxonomic differences more consistently than anything visible externally, so dissection of specimens is considered the best way to be sure of identification. There are also groups like the Tachnidae that require careful examination of things like minute bristles for reliable identification. Even in earwigs, the group I'm most familiar with, IDs can hinge on details of the feet and antennae that are visible without dissection, but rarely in good focus in images. Then there are details that can only be seen by turning the subject over and looking closely (true of a great many spiders).
There are also cases where it's discovered that what was considered one species is really several. Likewise, an identification may be called into question based on new information or changes in theory. The visible differences to examine for confirmation may not be captured in the original images, because no one knew what to look for- or there may be no visible difference. If you have a voucher specimen, you can always go back and reexamine it or test things like DNA. Or there may be questions no one has even thought of yet that could be answered someday using the specimen.
In short, an identification backed by a voucher specimen is better in just about every way than an identification based on an image alone.
So we should immediately have everyone take voucher specimens for every picture- right?
Actually, no. There are practical and theoretical factors to consider first:
First of all, a high-volume site like ours could conceivably overwhelm anyone that agreed to take the specimens if care isn't taken to be selective: we have over a quarter-million images accumulated over just 6 years, with the rate no doubt still increasing. The bugs represented by even a small fraction of those submissions would take a lot of labor to process and space to store. Does anyone really need thousands of specimens of common, no-brainer-ID species like Wheel Bugs in a time of shrinking resources?
Second, education about techniques and quality control is important. We've all seen images posted by folks who want to know if the spider they stomped is a Brown Recluse- imagine that spider after a trip through the mail. And ID is theoretically possible if a sphinx caterpillar is tossed in an envelope and mailed- but I wouldn't want to be the one opening that envelope!
Third, we need to think about legal and ethical pitfalls- there are locations like national parks and threatened populations that should be off-limits, for instance. What restrictions are there on sending pest species across state lines? What about species that might incur risks in order to collect them? How do we make sure we're not leading people to do something illegal and/or dangerous and/or wrong?
Fourth, people tend to look through the guide until they find something that looks like their bug. Are we misleading people by posting images of bugs that can't be identified that way? What do we need to do to educate people in such cases?
Not that these are fatal problems or even require much thought- it's just easier to deal with things you're aware of beforehand.
So, what should we do?
Some of this is already going on. Tom Murray, for instance, regularly collects some of the bugs he photographs, and he has informal arrangements to send specimens to various experts if requested. Some experts have offered to accept and ID any specimens sent them that are within their specialties. Mark Dreiling, among others, provides specimens for the Barcode of Life lepidopteran-DNA project, and in return gets IDs.
I think we should expand on this and work out ways to match contributors to IDers/repositories, but without inviting the world to indiscriminately dump on the latter. Perhaps we can come up with a system of gatekeepers or intermediaries who receive requests for a place to send specimens, then provide address and contact information when it's appropriate. Some recipients are set up for dealing with the public, so it won't be necessary- but I think we'll get much better participation if we have such an option to offer.
We should arrive at ways to encourage people to take voucher specimens where they're needed, and educate them about the limits of IDing certain taxa from images- at the very least through wording on guide pages, if not some system of codes, etc. Some of this might take the form of an article outlining specific groups that should be vouchered- though a comprehensive list would be too big to be practical.
We should also have an article explaining standard mounting, preservation and shipping techniques, with a list to refer to specify which to use for a specific type of specimen.
We also should come up with standards for documentation and cross-referencing, so the specimens received can be easily, reliably and consistently matched with the images
I know I've probably gone into too much detail, but at least it will give raw material to pick and choose from in our discussion