76 THE BUTTEltFLY VIVARIUM. 



and in Diptera, in nearly all cases where the head is 

 only of a membranous texture. In Coleoptera, 

 eyes are generally found to exist among the carni- 

 vorous and herbivorous feeders, and in Diptera 

 among the Gnat classes. Some larvae of Hymeno- 

 ptera and Lepidoptera, that is, of the clear-winged, 

 and scale-winged families, composed respectively of 

 the Bee tribe, and of Butterflies and Moths, are 

 also without eyes ; but most of the Lepidopterous 

 larvae are well provided with these organs. 



In a few of the water larvae the eyes are nume- 

 rously facetted like those of the perfect insect, as in 

 the larvae; of the Dragon-fly; but, with these excep- 

 tions, the eyes of larvae are generally simple, and 

 consist of very small globules, which in many cases 

 are only visible with the assistance of the microscope. 

 The number of eyes is variable. In the Tele- 

 phoroides, a class of Beetles, and in some of the 

 Saw-flies, the larvae have but one eye ; those 

 of the Cassida, another family of Beetles, have 

 three ; the larvae of another set of Beetles, the 

 Staphylides, have four; and some Coleopterous 

 larvae have five or six. When there are several 

 eyes, they sometimes differ very conspicuously in 

 size, and also in other respects, the smallest having 

 neither pupil nor iris. In the larvae of Lepido- 



