TEIfTHREDINTD^. 223 



mountain-ash. It appears in Jnne and September. The &j is 

 shiny black, with the tips of the four anterior femora, and the 

 tibiae and tarsi, dull white. An egg-parasite, belonging to the 

 genus Encyrtus, renders, according to Peck, a great number 

 of its eggs abortive. 



The Rose-slug, Selandria rosce Harris, is longer than the Pear- 

 slug, the body being scarcely thickened anteriorly, and not 

 covered with slime. It is pale-green and yellowish beneath. 

 It appears in July and August, and does great injury in dis- 

 figuring and killing the leaves of the 

 rose, which remain dried and with- 

 ered on the bush. When full-fed, 

 the larva, like the Pear-slug, makes 

 a cocoon beneath the surface of the 

 ground. The flies are seen in abund- 

 ance about the rose-bushes as soon S'lg. 149. 

 as the leaves are expanded, when they may be caught with 

 nets, or the hand on cloudy days. Hand-picking, and the 

 application of a very weak solution of carbolic acid, coal oil, 

 whale oil soap, or quassia, are useful in killing the larvae. 



On the 25th of July a young friend brought me a large num- 

 ber of some remarkable larvse (Fig. 149, natural size) of a 

 saw-fly, which I surmised might belong to this genus. It pre- 

 sented the appearance of an animated, white, cottony mass, 

 about an inch long and two-thirds as high. The head of the 

 larva is rounded, pale whitish, and covered with a snow-white 



powdery secretion, with prominent 

 black eyes. The body (Fig. 150, 

 naked larva) is cylindrical, with eight 

 Fig. 150. pairs of abdominal legs, the segments 



transversely wrinkled, pale pea-green, with a powdery secre- 

 tion low down on the sides, but above and on the back, arise 

 long, flattened masses of flocculent matter (exactly resembling 

 that produced by the woolly plant-lice and other Homopterous 

 Hemiptera) forming an irregular dense cottony mass, reaching 

 to a height equal to two-thirds the length of the worm, and con- 

 cealing the head and tail. On the 27th and 28th of July the 

 larvae moulted, leaving the cast skins on the leaf. They were 

 then naked, a little thicker than before, of a pale-green color. 



