222 AN INTRODUCTION TO ENTOMOLOGY. 



furnished with a pterostigma. The anal space of the second pair 

 of wings is small. The third segment of the tarsi is dilated and 

 bilobed ; and the fourth is very short. The abdomen in the female 

 is furnished with a long ovipositor. The larvae differ from all other 

 Sialidae in not being aquatic; they are found under bark. 



Those species of this genus that have no ocelli have been placed 

 by some writers in a distinct genus, Inocellia. 



Family II. — HEMEROBIADAE* 



{Ant-lions, Lace-winged Flies, ct al.) 



The Hemerobiadae is a family of considerable extent ; and repre- 

 sentatives of it are very common throughout our country. As a 

 rule they are delicate insects, with large, gauzy wings. These wings 

 are narrow, having no anal space ; in this respect they resemble the 

 wings of the Panorpidae. But the members of this family differ 

 from the Panorpidae in not having the mouth-parts prolonged into 

 a rostrum. The larvae of the Hemerobiadae are predaceous ; and 

 they are remarkable for having the mouth-parts formed for sucking. 

 They thus form an apparent exception to the characters of the order 

 Neuroptera. The form of these mouth-parts is a very unusual one. 

 It is well shown in the larva of the Ant-lion, where these organs are 

 large enough to be easily studied. The mandibles are very long; 

 on the ventral aspect of each there is a furrow the entire length ; 

 into this furrow the long and slender maxilla fits. In this way the 

 mandible and maxilla of each side form a tube through which the 

 blood of the prey of the insect can be drawn. 



Five sub-families are represented in our fauna. These can be 

 separated by the following table : 



TABLE OF SUB-FAMILIES OF HEMEROBIAD^. 



A. Prothorax not greatly elongated ; the three pairs of legs similar in structure. 

 B. Wings with very few veins, and covered with whitish powder. 



I. CONIOPTERYGIN/E. 



BB. Wings with numerous veins, and not covered with powder. 

 C. Antennae without terminal enlargement. 



D. Subcostal vein joined to the median before the end of the wing; the 

 principal sector parallel to the median vein and giving rise to the 

 other sectors.! {Sisyra, Polyst&chotcs.) 2. Hemerobiin/E. 



* Hemerobiadae, Hemerobius: hemera {rjuepa), day; bios (fSioS), life, 

 f For explanation of terms see Fig. 71, p. 73. 



