314 NATURAL HISTORY OF ARTHROPODS. 



in cases and mines, or not noticed by birds on account of their minuteness ; as a result 

 of this imnmnity from attack species of Chrysomelidije often become serious pests, as 

 is the case with the Colorado potato-beetle. 



The pupal state is passed, as a rule, as follows : underground, often with slight 

 cocoon, by the first half of the larvas mentioned in Lacordaire's second group, and by 

 some of those of his third and fourth groups ; under water in a cocoon attached to 

 stems of water-plants, by species of his first group ; in the leaf-mines by some species 

 in his third group ; upon leaves by the second half of his second group, and by most 

 of his fourth groujj ; and in larval cases by the species of his fifth group. 



Entomologists usually divide the Chrysomelidae into tribes, divisions which, to a 

 certain extent, coincide with the groups of larvae before mentioned, but forms of espe- 

 cial interest will be discussed here in their systematic order, without further sub- 

 division of the family. 



Sjjecies of Cassida and allied forms are recognized by the excessively wide margins 

 of the prothorax and elytra, and by the head being partly or wholly concealed beneath 

 the forward margin of the prothorax, the whole insect thus presenting a flattened, 

 roundish, scale-like aspect. Among tropical species very brilliant coloration is found. 

 Desmonota variolosa is a round metallic-green species from South 

 America, not rarely seen set in jewelry ; its elytra are so hard as to 

 resist the point of a slender pin. Mesomphalia conspersa, another 

 South American species, which has an elevated protuberance formed 

 by the anterior part of the elytra, is dull metallic blackish green, 

 with velvety black in round punctures, and with six larger spots 

 Fig. 351.— iifeawn- \\x2X show as burnished gold through a downy pubescence. Many 

 of our own species which resemble Cassida, feed upon plants of the 

 jiotato family {Solanace<e), upon the sweet-potato {Ipomoea batatas),^ and others 

 of the morning-glory family {Convolvulaceai). Coptocycla auridadcea, found on 

 the wild morning-glor)', is brilliant gold-color, Avhich is said to vary in shade with 

 the emotions of the animal, and which disappears when the insect dies. The larva 

 of this species was long ago described by T. W. Harris, and later by Di'. C. Y. 

 Riley ; the latter added a description of the egg. The egg is about 0.04 of an 

 inch long, of rather irregular angular form, flat, and usually furnished with spine-like 

 appendages. They are laid singly upon the leaves of the food-plant of the larva. 

 The lar\'a is flat, oval, dark brown, with a j^aler shade upon the back, and is margined 

 with a row of branched spines ; while, by means of its anal fork, it carries over its 

 back, as protection from predaceous animals, a parasol made of its own molted skins 

 and excrement. Pu])ation takes place in a spiny, flattened pupa which is attached to 

 the leaves of the food-plant by a sticky secretion. Unlike the pupas of most beetles, 

 this one does not ha^'e its legs free, although it can raise itself up at will, perpendicu- 

 larly to the surface on which it is attached. The first brood of beetles emerge from 

 their ])upa3 about July, having undergone their metamorphoses in a few weeks, and lay 

 the eggs for a fall brood. 



Coptocycla clavata, a common potato-beetle in New England, is very dark brown, 

 with thin yellow margin, the transparency of which is interrupted by a dark brown 

 patch at the anterior extremity of, and another just behind, the middle of each elytron, 

 giving the beetle a curious turtle-like appearance, in fact the resemblance of species of 

 Cassida and Coptocycla to turtles has given them the common name of 'tortoise- 

 beetles.' 



