214 INSECTS INJURIOUS TO VEGETABLES 



Three species of aphides commonly occur on potato and are 

 apt also to attack tomato, eggplant, and other Solanacese. The 

 same is true of mealy-bugs. The aphides include the common 

 "green fly," ^ "black dolphin," " and "melon louse." " Some forms 

 of tree-hoppers and related species, and thrips also, attack 

 these plants. 



The Colorado Potato Beetle {Lcptinotarsa dcccmlincata Say.). 

 — Soon after the Civil War the Colorado potato beetle created 

 quite as great consternation as the San Jose scale at the present 

 time. There is perhaps no more familiar insect to those who 

 live a rural life, and every country boy or girl knows its two 

 active stages. It is still one of our worst pests owing to 

 the fact that we must wage more or less perpetual warfare to 

 suppress it. In its early days there seemed to be no check to 

 its increase, but in the course of years many natural enemies 

 have learned to prey upon it, until in many localities it is 

 largely kept in abeyance by such agencies. It is of peculiar 

 interest as being the direct cause of the use of Paris green 

 upon edible plants. Fortunately, with a little knowledge of the 

 habits of this insect, the use of arsenicals and the friendly 

 assistance of natural enemies, the insect can now be held in 

 practical subjection, otherwise it would be one of the greatest 

 scourges of this country. 



This insect is so well known that a description is hardly 

 necessary, but that there may be no danger of confusing it 

 with blister beetles and others of similar habits, with which 

 it is occasionally associated, a few words of description may be 

 given. The beetle is of the robust form shown in figure 136, 

 d, d, ochre yellow in color, with the wing-covers ornamented 

 with ten black lines. The eggs are oval and orange colored, 

 and are deposited in masses of a dozen (a, a) or more on the 

 lower surface of the leaves. The larvae or "slugs" {h, h) are 



^ Rhopalosiphum dianthi Schrk. "Aphis rumicis L. ^ Aphis gossypii Glov. 



