Leaf+Galls

Leaf Galls

 **Background Information:** Leaf galls are bumps and deformations, usually the result of insects or mites feeding on the leaves. The gall itself is the plant’s response to the irritation, but most are harmless to the overall health of the tree or shrub. Galls are caused by feeding or egg- laying activity by insects and mites. Either mechanical damage or salivary secretions by the insects initiate increased production of normal plant growth hormones. These plant hormones cause localized plant growth that can result in increases in cell size, also known as hypertrophy, and cell number, also known as hyperplasia. As outcome is an abnormal plant structure called a gall. However, despite the unsightly appearance, insects do not live in the galls. In fact, it is very likely that once you notice the galls the insects have moved on. However, they can do a lot of cosmetic damage to many plants and in particular trees. Many common trees are susceptible to leaf galls, especially in the spring such as: Maple, Oak, Elm and Hackberry. Once the gall appears on the leaf, there is no way to effectively control it due to unpredictable numbers of galls, on each leaf, which vary from season to season.

  ** Question :**  At first for our project, we were interested in finding out if leaf galls were harmful to the trees in anyway. Through our research we learned that that they did not cause any significant damage to the trees. We then decided to study how common leaf galls were and what was inside of leaf galls. ** Through background research, we had known that insects often lived inside leaf galls during the larval stages. We expected to find larva inside the galls by dissecting them. We also predicted that leaf galls were not going to be commonly seen on every tree at Flat Rock Brook, and therefore we knew that there were specific leaf galls which targeted specific trees.
 * Hypothesis :

   **Common Type of Leaf Gall We Discovered:** ====<span style="FONT-FAMILY: 'Comic Sans MS', cursive"><span style="FONT-FAMILY: 'Comic Sans MS', cursive"><span style="FONT-SIZE: 110%; FONT-FAMILY: 'Comic Sans MS', cursive">Vein Pocket Gall & Leaf Pocket Gall:  ====

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<span style="FONT-FAMILY: 'Comic Sans MS', cursive"><span style="FONT-FAMILY: 'Comic Sans MS', cursive"><span style="FONT-SIZE: 110%; FONT-FAMILY: 'Comic Sans MS', cursive">These galls are caused by the larval stages of very small flies called midges. Vein pocket galls are swellings that occur along mid- and lateral leaf veins of scrub and pin oaks. The process begins when the unfolding leaves begin to flatten out. At this time, the small midge lays its eggs. The tiny maggots move to the veins and begin to feed. In a few days they are covered by gall tissue and complete development by mid-spring. The mature larvae drop to the ground and remain there over the winter. A related midge species causes the marginal folds or leaf pockets that can be found on red oak or pin oak. Several small larvae may be found inside the swollen folds of the leaf.

<span style="FONT-SIZE: 130%; FONT-FAMILY: 'Comic Sans MS', cursive">**How Are Galls Made?** <span style="FONT-SIZE: 120%; FONT-FAMILY: 'Comic Sans MS', cursive"> There are four principle organisms which produce galls <span style="FONT-SIZE: 120%; FONT-FAMILY: 'Comic Sans MS', cursive"> Plant mites - microscopic, pale yellow or translucent organisms with slender, pear-shaped body and transverse ridges or lines. The gall producers are in their larval stage and have 4 legs. Mites produce simple galls ranging from leaf deformities such as pouches or pockets. <span style="FONT-SIZE: 120%; FONT-FAMILY: 'Comic Sans MS', cursive"> Aphids and plant lice - soft-bodied insects with sucking mouth parts. These insects produce complicated galls, wintering on the bark, then hatching out in the spring and attacking a bud to form their galls. <span style="FONT-SIZE: 120%; FONT-FAMILY: 'Comic Sans MS', cursive"> Gall midges - small delicate flies that are about 1/4 inches long, and have antennae. <span style="FONT-SIZE: 120%; FONT-FAMILY: 'Comic Sans MS', cursive"> Gall wasps - Wasp larvae that are formed usually on oaks.

Methods & Materials Results  Location  Conclusion  Past Studies Bibliography