mSEi C8 INJURl TO AORI( ULTURE. 191 



potato, before its introduction lived ou othei pla The 



of the apple and other fruii 

 were introduced into America lived od certain f( 

 such as the oak, elm, ash, mountain-ash, wild cherry, pop- 

 lar, h illow, etc. 



1 1 it forest-trees are also peculiarly liable to depredati 

 from h certain s] of which attack the r< 



others the bark, others the wood, many the leaves, and a 

 few the fruit or nuts. Thus the <>;ik harbors between five 

 or six hundred species, the hickory affords maintenance to 

 one hundred and forty recorded species, the birch to • 

 one hundred species, the maple to eighty-five, the poplar 

 eventy-two, while the pirn- yields food to over a hun- 

 dred different kinds. 



We will now very briefly notice the most common and 

 formidable pes our cultivated plants, referring 



the reader for further information to the list of works and 

 reports on economic entomology at the end of this book. 



Insects Injurious to Field and Garden Crops. 

 Injuring Wheat. 



The Joint-worm {Isosoina hordei Harris).— A mil 

 footless, yellowish-white maggot often forms blister-like 

 swellings between the - 1 and third joints <.f the stalk, 

 immediately above the lower joint in the sheathing bat 

 the leaf; remaining through the winter in the stubble, 

 w, or harvested grain, and changing int mall, 



shmlrr. black, four-winged insect, which di 

 ii the .-talks of young wheat late in May and ii 



This is one of the Chalcididae, and, unlike the majority 

 of the family, lives on plants. When wheat or I 

 from eight to ten inches high its growth bi c< m 

 checked; the lower leaves turn yellow, and 

 come bent. If the hints of the straw a- cammed, 



they will be found to be irregularly swolL i 

 between the Becpnd and third joints, '•' being 



