In the final hours before our deadline, as we finished up the introduction to Tracks & Sign of Insects, Noah threw in this sentence: “We no doubt missed many things and probably misidentified a few.” I knew the first part was true, but hoped he was wrong about the second part. Alas, as I have continued to delve deeper into the world of invertebrate tracking, I have indeed discovered that a few of the photos in our book are misidentified (although, to be fair, there is no “we” about it; I can take full credit for all of the mistakes discovered so far).
Fortunately, Stackpole has corrected all the errors I told them about for the second printing, which is now available. These are not all misidentifications; there were also some incorrectly cropped photographs and a number of mistakes in the index (which, thankfully, it was not our job to put together). The new books do not say “second printing” anywhere that I can see, but they are easily recognized because on the cover our names have been shifted to the left to make way for two gold medallions (as shown in the right sidebar). Stackpole has not yet sold all of the first printing copies, so the only way to be sure you’re getting the newer one if you order online is to get it at NorthernNaturalists.com. It’s not different enough to warrant buying it if you already have the book, but I’m mentioning this for those who don’t have a copy yet.
Anyway, one of my bigger goofs involves the “oak apple” galls on page 390. It turns out there are several more kinds in New England than I thought when I put that chapter together. Two types are illustrated, in each case with one of the galls cut open to show the interior, and both are mislabeled. They are the same two types that I’ve placed side by side in the photo below.
The one on the left is labeled in the first printing as Amphibolips confluenta, the “spongy oak apple.” It is solid on the inside, and when fresh has a moist, applelike consistency; I incorrectly assumed that this becomes spongy when dry. The reason I had not found this gall’s correct identification among the “oak apples” in the gall references I had checked is that it isn’t an oak apple. Oak apples form on oak leaves, or in some cases consume the entire leaf, emerging directly from the leaf bud. Ironically, these galls that are more applelike inside than any of the true oak apples are called plum galls (Amphibolips quercusjuglans), and they form on the sides of acorn caps. I have yet to find one still attached, but there is an example here. I’ve collected a number of fallen oak plums, but so far all that have emerged are moth caterpillars. I may have to wait a while to see the wasps. MJ Hatfield collected a bunch of galls on September 2, 2008, and had the first adult emerge on April 3, 2011 (see here)–after three winters!
True “spongy oak apples” are more like this (the one on the left is torn open to show the spongy interior)…
…except I’m not sure if these are A. confluenta or A. quercusspongifica. The two are described in the literature as being similar in size and appearance, but apparently there is a difference in phenology. Weld (in Cynipid Galls of the Eastern United States, privately published in 1959) wrote that adults of A. quercusspongifica have all emerged from their galls by the end of June [in Chicago, DC, Connecticut, and Ontario], whereas galls of A. confluenta in Ithaca, NY still contained pupae on August 1 and adults on September 12, and in Connecticut and Toronto adults were recorded as emerging from galls in November. The photo above was taken in May, as was the one below, which (showing a shinier and bumpier gall) seems to represent a different species:
I’m hoping to get adults from the various spongy oak apples this year and get them sorted once and for all. Now, back to the first photo in this post. In the first printing, the type of gall shown on the right was labeled as Amphibolips quercusinanis, the “larger empty oak apple.” The gall made by that species is in fact very similar to this one: spotted on the outside; largely hollow inside, with the central cell (in which the wasp larva develops) suspended by radiating fibers. I probably could have gotten away with keeping that label without anyone calling me on it. But the spotted, “empty” oak apples that are found in late August, as the ones shown in the book were, are caused by Amphibolips cookii. The true A. quercusinanis adults have already emerged by the end of June. A. quercusinanis galls are the ones that dry and become like brown ping-pong balls littering the forest floor; A. cookii galls wrinkle when they dry, and they average substantially smaller (the ones shown in the book are exceptionally large at about an inch across). There are still other Amphibolips oak apples in New England, not all of which are caused by species that have been given names. A. quercusinanis galls are so common that I have apparently never bothered to take a picture of one, but I did get an adult from one last year:
At 5 mm long, this is the largest gall wasp I’ve seen.
Someday, when I’ve got a better handle on them, I’d like to make an updated, more user-friendly and better illustrated version of Weld’s book on cynipid galls of eastern North America. Since the wasps can take several years to develop, and since most of the galls I collect produce parasitoids or inquilines, progress is slow, and I doubt that’s going to be anytime soon.