INSECTS. 



197 



picked off the adults. Nature soon established a balance, and now the 

 potato-beetle, though still a nuisance, has far less prominence than it had 

 a dozen years ago. 



It is rather amusing to consider the alarm the spread of the potato- 

 beetle caused in Europe. Severe penalties were imposed upon any one 

 who should bring the pests, their eggs, or their larvae into German}- or 

 the British possessions. In the light of our experience with the beetle it 

 would seem as if the scare was greater than the subject would warrant, 

 but still there is no doubt that Europe is better off without the beetle-. 



One of the most interesting features connected with the spread of the 

 potato-beetle is the change in the character of its food. In its western 

 home it fed upon the prickly sand-bur (Solcmum rostratum), which, though 

 it belonged to the same genus as the potato (S. tuberosum), differed from 

 it considerably in character. In the east it has varied its diet consider- 

 ably ; for besides the potato, bitter-sweet, and deadly night-shade (all of 

 which belong to the same genus) it will eat thistles, pigweed, cabbage, and 

 several other plants. This change is the more remarkable since another 

 closely allied beetle (shown on the right of our cut), living in the southern 

 states, there feeds on the horse-nettle (Solcmum carolinense), a close ally 

 of the potato, but does not attack the potato itself. These two beetles, 

 as will be seen from the cut, are very similar in appearance ; the Colo- 

 rado potato-beetle has ten black lines on the wing-covers ; the other has 

 but eight. 



Before the advent of the species just mentioned, the term potato-beetle 

 was universally applied to a much smaller form, with yellow head, and three 

 black stripes upon the wing-covers, much like the next species, but larger, 

 and differing considerably in anatomical details. The larvae of this species 

 have a habit which is also found in some of the allied forms. "After 

 making a hearty meal upon the leaves of the potato, they cover themseh 

 with their own filth. The vent is situated upon the upper side of the last 

 ring [of the body], so that their dung falls upon their backs, and, by 

 motions of the body, is pushed forwards as fast as it accumulates, towards the 

 head, until the whole of the back is entirely covered with it. This cover- 

 ing shelters their soft and tender bodies from the heat of 

 the sun, and probably serves to secure them from the attacks 

 of their enemies." 



The gardener frequently has occasion to lament the loss 

 of his young cucumber-plants. One day they will thrust 

 their first leaves above the soil ; a few days later they will 

 be cut off and withered, the cut being made just below the surface of the 

 earth. This is done by the larvae of a small yellow beetle, with black head, 



