NOTES ON THE PEAR-SLUG.* 

 Eriocampoides limacina Retz. 



By R. L. Webster. 



Recent Injury. Nearly every year cherry and plum trees 

 in Iowa suffer much injury by the common pear-slug. While 

 the control of this insect has never been considered a difficult 

 problem, yet it happens frequently that foliage is greatly dam- 

 aged before one is aware that any slugs are present. 



Serious damage is sometimes caused to cherry trees. Young 

 cherry trees in the town of Ames have been killed as a result of 

 defoliation following the injury by the slugs. 



Appearance of the Injury. The slugs feed on the upper 

 surface of the leaves, eating the parencyhma and leaving only 

 the veins and the lower epidermis. Leaves thus eaten, dry, 

 turn brown, curl up and fall from the tree. Frequently in- 

 fested trees are left entirely bare of foliage in midsummer. 



The Insect's Appearance. The insects in question are 

 dark, olive colored slugs, with a slimy covering. The fore part 

 of the body, just back of the head, is broad, but it tapers back 

 of this. Where the slugs are common a peculiar sour odor 

 may be noticed. 



The slugs molt five times, and when mature they are about 

 2-5 of an inch long. After the last molt the slug has a clean and 

 dry skin, quite free of slime, and orange in color. These orange 

 slugs go to the ground and form small earthen cells in which to 

 pupate. When the adult sawfiies emerge they deposit eggs in 

 the tissue of plants on which the young slugs are to feed. 



past history and distribution. 



This insect has long been known in Europe. As far back as 

 1740 Reaumur gave an account of the pest and its injury. The 

 first American account was written by Prof. Wm. D. Peck, of 

 Harvard, and published in 1799. 



Professor Peck wrote an essay on the insect, entitled the 

 "Natural History of the Slug- Worm," which won for him a 

 gold medal and a prize of fifty dollars, given by the Massachu- 



* Read at the Minneapolis Meeting, Dec. 28. 1910, in joint session with the Association of Economic 

 Entomologists. 



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