TENTHREDINID^. 215 



question whether the increase in size of the eggs of the Saw- 

 fly is not rather due to the same cause. 



The punctures in the plant often lead, in some genera, to the 

 production of galls, in which the larvae live, thus showing 

 the near relationship of this family to the gall-flies (Cynipidae) . 



The larvae strongly resemble caterpillars, but there are six 

 to eight pairs of abdominal legs, whei'eas the caterpillar has 

 but five pairs. Many species curl the hind body up spirally 

 when feeding or at rest. They are usually green, with lines 

 and markings of various colors. They usually moult fom* 

 times, the last change being the most marked. Most of the 

 larvae secrete silk and spin a tough cocoon, in which they liiber- 

 nate in the larva, and often in the pupa state. The pupa has 

 free limbs, as in the other families. The eggs are usually de- 

 posited in the leaves of plants, but in a few cases, according 

 to Norton, in slender or hollow stems. While some are slug- 

 shaped, like the Pear-slug, others like Lyda inanita, mentioned 

 by Westwood, live on rose bushes, and construct a "portable 

 case, formed of bits of rose-leaves arranged in a spiral coil ; " 

 and other species are leaf-rollers, like the Tortricids. The 

 larva of Cephus does injury to grain, in Europe, by boring 

 within the stems of wheat. A remarkable instance of the care 

 of the saw-fly for her young, is recorded by Mr. R. II. Lewis, 

 who observed in Australia, the female of Perga Lewisii deposit 

 its eggs in a slit next the midribs of an Eucalyptus leaf. They 

 were placed transversely in a double series. "On this leaf 

 the mother sits till the exclusion of the larvae ; and as soon as 

 these are hatched, the parent follows them, sitting with out- 

 stretched legs over her brood, protecting them from the attacks 

 of parasites and other enemies with admirable perseverance." 

 (Westwood.) 



The species are mostly limited to the temperate zone, but 

 few being found in the tropics. The perfect insects mostly 

 occur in the early summer, and are found on the leaves of the 

 trees they infest, or feeding on flowers, especially those of 

 the umbelliferous plants. 



The genus Girnhex contains our largest species, the antennae 

 ending in a knob. C. Americana Leach is widely distributed, 

 and varies greatly in color. The large whitish larva, with a 



