Workers in Plant Tissues. 



posed entirely of females, all similar to one another, are 

 produced. 



From the above necessarily brief outline it will 

 be seen that these tiny Gall-flies, which by means of 

 their minute ovipositors are able to pierce the tsssues 

 of the plants, deposit their eggs beneath the tissues, 

 and cause those changes which produce such strange 

 and often beautiful growths, have a most singular and 

 interesting life history. 



There are a large number of Caterpillars which, 

 from their habit of making their homes in leaves 

 which they curl up in various ways, are popularly called 

 Leaf-rollers. They are quite expert little craftsmen 

 in their own humble fashion, some using a single leaf, 

 others employing two or more in the construction of 

 their nest, and all display a wonderful variety in their 

 manner of accpmplishing the task. Some we find 

 bend the leaf longitudinally, and are content just to 

 fasten the two edges together; while others bend it 

 transversely, fixing the point of the leaf to the middle 

 vein. Some roll up the leaf longitudinally, so as to 

 produce a hollow cylinder of the same length as that 

 of the entire leaf; others roll it transversely, or cut 

 a slit and roll up only a small portion of the leaf. All 

 these Caterpillars are very small, and it is really not 

 by their own strength, but by their mechanical skill, 

 that they are able to roll up the leaves to form their 

 homes. 



Take, for instance, the little Caterpillar which in 

 some seasons causes considerable damage to the foliage 

 of the lilac bushes, and which is only about three- 

 sixteenths of an inch long. Selecting a point where 



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