378 



AN ECONOMIC ENTOMOLOGY. 



any evidence at present, there is a continuous breeding by female 

 individuals only. 



There are only a very few injurious species among these gall- 

 flies. Occasionally we find on blackberry stems an irregular, 



warty swelling, and if 

 ^^^- 435- this be cut into, it will 



be found full of cells 

 occupied by these little 

 Cynipid larvae. This 

 kind of gall is known 

 as " multicellular," be- 

 cause inhabited by nu- 

 merous specimens. 

 Similar galls are found 

 on the roots of rose 

 and plants of the same 

 natural family, and in 

 a few other cases cul- 

 tivated plants become 

 subject to gall growths. 

 As a matter of fact 

 these galls are scarcely 

 injurious, because in 

 most cases the plant 

 continues growing be- 

 yond them, or even if 

 a shoot is lost, perma- 

 nent injury is rarely 

 done. Certain species 



a, Pithy gall on blackberry, made by niaslrophus of oak-galls produce a 

 nebulosus ; b, section to show cells; c, larva; d, hlart stain 'Uld these 

 pupa. ^ ' ^- 1 



were at one time al- 

 most universally employed in making an ink of remarkable per- 

 manence. Even yet the law in some States requires for certain 

 records an ink of which oak-galls is one of the ingredients. 



It is a small step from parasitism upon vegetation to parasit- 

 ism upon animals, and hence it is not surprising to find that some 

 species of this family are parasitic on other insects. The differ- 

 ences between these forms and the true gall-makers are not easilj-- 



