122 PRINCIPAL HOUSEHOLD INSECTS. 



brown color. The antennse are clavate, or clubsliaped, and the thorax 

 has two shallow, longitudinal grooves on the upper surface and bears 

 six minute teeth like those of a saw on each side, as indicated at fig. 

 59, a. 



The larva is somewhat depressed, and nearly white in color, with 

 darker markings, as shown in the illustration [c). It has six legs and 

 an abdominal proleg, and is exceedingly active, running about, nibbling 

 here and there. 



When fully matured the larva fastens itself by means of some 

 adhesive matter, evidently excrementitious, to any convenient surface, 

 and thus attached transforms to pupa and afterward to imago. When 

 the insect is living in such granular substances as oatmeal and cracked 

 wheat a delicate case is constructed of fragments of these materials, 

 but when in flour aud meal often no covering is made. From data 

 acquired by experiment it is estimated that there may be six or seven 

 generations of this insect annually in the latitude of the District of 

 Columbia. During the summer months the life cycle requires but 

 twenty-four days; in spring, from six to ten weeks. At Washington, 

 it has been learned, the species winters over in the adult state, even in 

 a well-warmed indoor temperature. 



THE CADELLE. 

 (Tenehroides maiiritanicus Linn.) 



The term "cadelle" was first proposed years ago in France for the 

 larva of this insect. The Latin name was given to it in 1758, when it 

 was described as a species of Tenebrio and classified with the meal- 

 worms, the adult of which it very slightly resembles in its somber 

 color and depressed elongate form. It belongs, however, to a distinct 

 family, the Trogositidii^, and is considerably smaller than the meal- 

 worm beetles, measuring about a third of an inch. It is very dark, 

 shining brown in color, much flattened, and of the somewhat oblong 

 form indicated in the illustration (fig. 60, a). The antenna is shown, 

 much enlarged on page 123. The general appearance of the larva is 

 shown at c. It is fleshy and slender, measuring when full grown nearly 

 three fourths of an inch. It is whitish in color, with head and tip of 

 the anal segment dark brown, the latter terminating in two dark cor- 

 neous hooks. The three thoracic segments are also marked with dark 

 brown, as indicated in the figure. The pupa {h) is white. 



There has always been a difference of opinion in regard to the nature 

 of the food of Tenehroides mauritaniciis, some claiming that the insect 

 was carnivorous. It has been satisfactorily i^roven through experiment 

 by the writer that the insect is both herbivorous and predaceous. It is 

 most often found in cereals and in nuts, but may be occasionally taken 

 in other materials. 



