200 Forty-ninth Report on the State Museum 



The San Jose Scale, and Some Other Destructive Scale In- 

 sects of New York.* 



(Ord. Hemiptera : Subord. Homoptera: Fam. Coccid^.) 

 What Scale Insects Are. 

 There is a large class of small insects — some, indeed most, of which 

 require a magnifying glass for their observation, which are particularly 

 detrimental to fruit culture, yet from their inconspicuous appearance 

 usually escape notice until discovered when search is made for the cause 

 of the languishing condition or death of the tree or shrub infested by 

 them. Even then it is rather difficult to believe that the true cause has 

 been found in what often seems to be merely an unnatural roughening of 

 the bark or a moderate incrustation formed upon the surface. 



Classification. 



The species more commonly met with (the Diaspinae) have received 

 the name oi bark-lice, from the appearance of ihe young as they travel 

 over the bark for a few days after they are hatched ; and of scale-insects, 

 from the scale-like covering secreted by the insect and beneath which it 

 is hidden after it has fastened itself to the bark. Scientifically, they, 

 together with the "mealy-bugs," are known as Coccidse. In classifica- 

 tion they have place in that division of the Hemiptera (a large order of 

 suctorial insects) known as Homoptera, the wings being of a uniform 

 thickness throughout, and thereby distinguishing them from the other 

 division (Heteroptera) in which the front wings are thickened in their basal 

 half to a degree, often, approaching the elytra or wing-covers of beetles. 

 It is to this last-named division that the popular name of "bugs," has 

 become attached. All of the Hemiptera are suctorial, and take their food 

 through a beak or proboscis instead of by biting jaws. They difter 

 greatly in their structure, and in mode of development : the latter, in some 

 of the families, as in that of the Aphididas or the plant-lice, is of intense 



interest. 



Development. 



The development of the Coccidae is quite peculiar. The females do not 

 become perfected into Avinged creatures, but with age assume the form of 

 scales, or galls, or of grubs covered with wax or powder ; or become de- 

 graded beneath their sheltering scale into barely more than egg-sacs, 

 retaining only such simple organs as arie essential to their life dunng the 



' Reprinted from Eulletin of the New York State Museum, Vol. 3. No. 13, April i, 1895. 



