Northland Nature: Enterprising Northland insects enjoy diverse June plant growth

• An oak apple gall

An oak apple gall grows on the underside of a red oak leaf. Note its size, compared to a quarter. Contributed Photo

Talk about it

The greening month of May has truly lived up to its name, and the trees that were so bare six weeks ago are now lush with a deep green of their mature leaves.

Besides giving us a wealth of beauty and shade, this forest foliage is filled with many more happenings on these June days. We are not the only Northland residents who are glad to see the greening of the trees at this time of spring. Many others make use of the numerous leaves.

The trees put this new growth out in the sun so that they can use the light on these long days to manufacture needed sugars to survive. This newly made food source is then used to develop seeds from the earlier flowering time and to grow taller.

Trees grow in height only at this time of year: a time of plentiful moisture, light and warm temperatures. As May is the greening month, June is the growing month. And many of the local fauna make use of the new arboreal additions as well.

Birds and squirrels hide among the greenery and some use these flat green food-making organs for nests. The leaves not only provide ample nesting sites and protection: the birds are also able to feed right in their own neighborhood.

Newly developed leaves are quickly chosen as meals by a huge variety of hatched caterpillars. These include the well-known forest tent caterpillars (often misidentified as army worms), but a plethora of other species also abound in the forests of June.

The young of many kinds of insects hatch during these warming days, and immediately eat and grow. And if there are caterpillars, there is a large number of birds to feed on them.

Indeed, many of the recently arrived songbirds time their return for the annual caterpillar outbreak. Caterpillars put up a fight to avoid being eaten in a great variety of ways, the most obvious by sheer population, but they also take on strange colorations, mimicry and just plain tasting bad as a way of not being completely wiped out by the feathered feeders.

And then there are the gall makers.

Insect galls may be best known as the lumpy ball-shaped objects that grow on goldenrod stems later in the summer. These are definitely galls, but they flourish on many other plants as well, including trees.

Most insect galls are swellings on a plant, caused by the egg or young of an insect. Substances from the developing youth cause the plant to enlarge. The insects then live under the protection of the big growth.

Nearly every species of tree will have a specific type of insect that form galls on it. Though cherry, sumac and maple are some of the ones that are easy to see, galls are most numerous on oaks.

Last week as I walked a wooded trail, I noted green oak leaves on the ground. One held a large ball-shaped growth. Upon closer inspection, I could see that it was a gall often called “oak apple” because of its large one-inch size.

Not only was it big, but it had grown so fast. Red oaks are one of the last forest trees to leaf out, and in only a couple of weeks the gall had reached this size. The gall was green and mostly hollow; it will turn brown as it ages.

Insect galls tend to be species-specific as to where they grow, and the insect that caused it can be identified by the uniqueness of the gall. This growth was the work of a gall wasp, a tiny stingless wasp common in the region, but hard to see.

The presence of this structure on a red oak leaf in early June told me once again of the diversity and opportunistic conditions of Northland insects. The young will grow in the gall until maturing and eating its way out, late in the season. There will be plenty more to see in the coming months as insects are able to live with Northland plants.

Editor’s Note: See next week’s Blueprint edition for a story about forest tent caterpillers.

Retired teacher Larry Weber is the author of several books, including “Butterflies of the North Woods,” “Spiders of the North Woods” and “Webwood.” Contact him c/o news@pinejournal.com.

Tags: local columns, northland nature, outdoors