WHAT SCALE INSECTS ABE 



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

 require a magnifying glass for their observation, which are particu- 

 larly 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. 



The species more commonly met with (the Diaspinse) have 

 received the name of bark-lice, from the appearance of the 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 classification 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 differ greatly in their structure, and in modes of development ; 

 the latter, in some of the families, as in that of the Aphididas or 

 plant-lice, is of intense interest. 



The development of the Coccidee is quite peculiar. The females 

 do not become perfected into winged creatures, but with age assume 

 the form of scales or galls, or of grubs covered with wax or powder ; 

 or become degraded beneath their sheltering scale into barely more 

 than egg-sacs, retaining only such simple organs as are essential to 

 their life during the reproduction of their young. The male, how- 

 ever, undergoes a complete transformation and becomes winged, but 

 with only a single pair of wings of very simple structure (see in 

 Figures 3, 2 and 3 in Plates I, II and YII). It lives but a day 



