42 



HALF HOUKS WITH INSECTS. [Packaud. 



fittachcd. In the Pine-leaf Scale insect (Fig. 32 ; a, the leaves 

 with the scales of natural size ; &, male scale ; c, female. Fig. 

 29, the male greatly enlarged, after Riley) the scale marked 

 d is much wider than in the one marked c, which lives on a 

 narrower needle of the pine. Indeed so great is the range 

 of variation that when we regard the larva-like females, it 

 becomes difficult to draw the limits between the species. 



Nearly every tree of the orchard and our hard Avood, de- 

 ciduous trees harbor one or more kinds of scale insect. The 

 oyster shell scale insect of the apple tree is an unfailing at- 

 tendant and to young trees is extremely pernicious. The 

 orange trees of Florida have been at times grievously afflicted 

 by another species, while our ornamental shrubs and vines, 



Fig. 33. 



Parasite of Scale Insect. 



and hot-house plants suffer greatly from their attacks. The 

 injury they do is the result of their vast numbers, since 

 they cluster on the leaves and stems of plants, puncturing 

 the skin or bark and sucking the sap flowing beneath. 



Happily they have their parasites, certain exceedingly 

 small ichneumon flies, such as CoccopJiagus and Aplielinus 

 (Fig. 33 ; &, antcnnre, c, larva, all greatly enlarged, after 

 LcBaron) which prey upon them. It is not rare to find a 

 scale insect with a large round hole in the top of its bod}^, 

 through which the ichneumon has escaped. Mites are also 

 known to prey upon their eggs. 



The Imported Currant Saio Fly. — This dreadful pest of 

 currant and gooseberry bushes affords an excellent example 

 of the mode in which an imported animal flourishes far 



10 



