Tom Turpin
Professor of
Purdue University







It Takes Gall

Almost everyone has, at one time or another, noticed a deformity in plant growth called a gall. These often grotesque plan abnormalities can be caused by insects. Gall-causing insects lay their eggs in plant tissue, and the developing larvae cause the plant to respond with abnormal growth, known as a gall. Some beetles, moths, flies, and wasps are among the insect gall-makers.

Galls have been recognized by humankind for centuries, and in fact, galls are better known than the insects that produce them. The galls are numerous and showy; their insect residents, on the other hand, are quite small and difficult to see.

From times of old and even today, galls have been used to produce tannic acid and dyes, including one dye called Turkey Red. The best permanent inks have, for years, been produced from galls. The Aleppo gall, found in Eastern Europe and Western Asia, is used for this purpose. In some places, the law requires that permanent records be made with ink derived from galls. Such an ink is used by the United States Treasury and the Bank of England.

The word “gall” has a double meaning in the English language. The Latin word “galla” meant a gall-nut, the plant growth abnormality. The Anglo-Saxon word “gall” meant bitter, hence the word “gallbladder” to identify the bile-holding sac associated with the liver. Shakespeare, no doubt, had both meanings in mind in “Twelfth Night” when he had Sir Toby Belch tell Sir Andrew to use “gall enough” in the ink to pen a challenge to duel Viola.

Gall insects attack over one-half of all plant families, and almost all parts of the plant are subject to infestation. In general, gall-makers produce the same type of fall on different plants.

Galls are generally named according to the way they look. For instance, we have the hedgehog gall, which must look a bit like a hedgehog. Many galls remind folks of fruits and vegetables, including the apple, potato, and pea galls of oak. We also find spindle, hairy, and spiney galls on oak. And there are button galls, cup galls, and the red sea urchin galls. Bullet galls and vase galls have been known to occur on the same plant as the wool-sower galls.

One of the most interesting of the galls is the jumping oak gall. When this gall falls from its oak tree host, the larvae inside cause the gall to jump. The popping activity of the jumping gall is similar to that of Mexican jumping beans, which is also caused by an insect inhabitant.

Even in the insect world, a little gall can sometimes attract attention!



Writer: Tom Turpin
Editor: Carol McGrew