Nutcracker

Think of the fierce energy concentrated in an acorn! You plant it in the ground and it explodes into an oak.

~George Bernard Shaw

The trail cameras have been busy these past few months with lots of images of squirrels (too many), raccoons, opossums, two coyotes (finally, I was beginning to wonder what happened), a few raptors, loads of deer, some neighbor kids, and, unfortunately, too many outdoor cats. I tend to leave the cameras in one location for some time to try to get a feel for the wildlife activity in that particular area. I moved one camera slightly back in October to get a better angle on what seemed to be a lot of foraging around a large Northern Red Oak down-slope from the house. This has been an off year for acorns in our woods with almost no White Oak acorns produced. White Oak acorns mature in summer and drop in the fall (one year). The red oak group of acorns take 2 years to drop, but some are produced every spring, so, even in a bad acorn production year, there are some red oak acorns still on the tree. So, in our woods this year, the critters that rely on acorns for a portion of their autumn diet have been concentrating on the red oaks.

The deer have been particularly busy at the large red oaks as there isn’t a lot of understory that they haven’t already over-browsed. The one camera placed near the large Northern Red Oak has had a lot of clips taken of the animals scavenging the acorns that have dropped. Interestingly, very few squirrels have been seen eating the acorns on the ground, probably because they tend to do a lot of their foraging in the tree tops. Here is a selection of the goings on at the old oak tree this season…

A group of deer foraging under the large Northern Red Oak on our property

Sometimes they don’t play nice while searching for acorns.

A doe strikes at another deer to drive her away from what might be a good spot for acorns

Sometimes there are other woodland critters getting in on the bounty under the oak tree…

A Southern Flying Squirrel scurries around the oak trunk
A deer wanders over to check out what the raccoon may have found (raccoons were common at night in the area around the tree)
A rabbit was a frequent visitor under the tree

What I enjoyed the most was watching deer crack the acorns – the way their jaws move, the sounds (sound up for these video clips).

A doe chews loudly on an acorn
Crunchy breakfast

The action under this tree was pretty constant, day and night, for a few weeks, lasting through about the third week of November when most of the acorn drop ceased. Now, an occasional visit by a deer is captured on that camera, but they typically are seen sniffing the leaves a bit before moving on. Winter has set in and times will be tougher for some of our woodland neighbors until the spring green starts to appear.

This is Nuts, Part 2

Each year insects heavily attack northern red oak acorns and destroy a large percentage of them, greatly reducing the number of acorns available to produce seedlings and feed wildlife.

~Lester P. Gibson

No, this isn’t what you think…it really is a post about acorns (I need a break from the other nuttiness). It is a quick follow-up to my recent post on acorn weevils. I became fascinated with the goings-on inside acorns after seeing the weevil larva pull itself out of the nut and wanted to learn more.

acorns

It is a very good year for acorns (click photos to enlarge)

I collected 100 acorns and did the float test I mentioned in that first post (I used only white oak acorns for this test although the photo above shows both white and northern red oak acorns). An astonishing 45 out of 100 acorns were floaters, indicating they were “unsound”, which means they possibly had acorn weevil larvae or some other insect inside. I separated those out and placed them in a plastic tub and have been collecting the larvae that emerge. In the last week, 13 insect larvae were found crawling around in the tub. Most were the large chubby weevil grubs I found before, but a few were different.

Acorn insect larvae

Acorn insect larvae

The photo above shows samples of the three types of larvae that have emerged…the large weevil grub on the right; a much smaller weevil grub in the middle; and a moth larva on the left.

Acorn weevil larvae big and little

Acorn weevil larvae – big and little

A few of the grubs were small versions of the chubby acorn weevil larvae. These may be from a different species of weevil rather than simply smaller versions of the dominant larvae I have seen. Online resources state there is another acorn weevil with a short (less than half its body length) rostrum that lays its eggs in acorns that are on the ground (the species I showed in the last post, with the long rostrum, lays eggs in developing acorns on the tree). And it appears there may be more than one species of weevil that lays eggs in developing acorns, so the small larva shown in the middle above could certainly be that of a different species.

Acorn moth larva and acorn weevil larva

Acorn moth larva (left) and acorn weevil larva (right)

There was also one caterpillar that crawled out of an acorn this week. From what I can decipher from scattered references, there may be a couple of species of small moths that lay eggs in acorns. The information I found suggests they lay eggs into existing cracks or openings in acorns (including the exit holes of acorn weevil larvae), although one reference also stated at least one species of moth caterpillar can chew through the shell of an acorn.

Acorn moth larva

Acorn moth larva

The moth caterpillars are easily distinguished from the weevil larvae by their more elongate shape, and the presence of three pair of legs just behind the head capsule (the weevil larvae lack legs). I placed several of the insect larvae in small containers with potting soil and hope to rear them to see what emerges next spring (or whenever since some may take more than one year). The literature indicates a wide range in the percent of any years’ acorn crop that is infected with insect larvae, depending on location and oak species. The study cited in the opening quote found an average of 52% of the northern red oak acorns at a site in Ohio were damaged by insects of various sorts. My very limited “study” indicates 45% are unsound.

Hickory nuts with weevil exit hole

Hickory nuts with exit holes

And it’s not just in acorns. It is also a good year for the hickory nuts in our woods, and, much to my surprise, I am finding a small percentage that have very neat exit holes in them. These nuts have much harder and thicker shells than acorns, so it will be interesting to see what is making them (I am assuming a weevil larva of some sort). Seems like there are some pretty amazing things going on out there in the forest.