112 MB. E. P. STEBBING ON THE LIFE-H1STOKY OF 



dark madder-brown in colour, convex above and flat ventrally, the dorsal segments 

 well marked and ridged, the lateral edges flattened. Legs yellowish or madder-brown. 



When full-grown the insect is usually entirely enshrouded in a thick mass of long fine 

 filamentous wool. This wool is secreted from the segmental divisions of the thorax and 

 body. Length about 125 niillim. PI. 22. fig. 2 shows a female without the "wool" 

 covering, just before egg-laying, fig. 3 a female just commencing to develop the wool 

 covering and to oviposit, and fig. 4 a female with the eggs almost fully if not completely 

 laid and covered to a great extent with the wool covering (some of it in the drawing 

 has been removed to show the eggs). 



"Wall-grown Larva or Nymph (Sexupar.*:). — Elongate elliptical, pointed at both ends. 

 Shining, madder-brown, with two dull yellow swellings on either side of the thorax, 

 which are the wings beneath the skin, and give a humped appearance to the thorax 

 dorsally. The transverse annuli of the body are faintly visible. Body very convex 

 dorsally, the lateral edges set with a longitudinal row of tubercles. Length about 1'45 

 to 1-55 millim. (PI. 22. fig. 6.) 



Winged Insect (Sextjpar^:). — Umber-brown to blackish, with four transparent wings 

 with a faint brownish tinge, the base of the main vein yellow medianly, otherwise all the 

 veins brownish. Head umber-brown, with exserted antenna?, 4-jointed (or 5-jointed, the 

 aasal joint very short), 1 (or 2) thick, square, short, other 3 narrower than 1, elongate, 

 swollen medianly, last shortest. Thorax black, emarginate anteriorly, with a flat 

 elongate heart-shaped raised edge medianly, enclosing a smooth depression having 

 this shape OO on prothorax and a prominent lateral spine on side of mesothorax. 

 Body black, rather flat, the abdominal margin of the segments prominent. Legs dull 

 umber-brown. 



No " wool " material visible on the insect when it first issues from the ruptured skin 

 of the nymph. 



Some twelve hours after leaving the skin of the nymph, short curling white cottony or 

 " wool " filaments begin to appear : 



(1) At base of head at its junction with the prothorax. 



(2) Two circular patches placed transversely in the sunken depression on the 



prothorax. 



(3) An irregular patch on the meso- and metathorax. 



(4) A much larger continuous mass of wool filaments completely covering the dorsal 



surface of the abdomen. 

 PI. 22. fig. 7 shows this fly when it has just begun to develop the woolly masses on 

 head, thorax, and abdomen. 



Life-History. 



The winter is passed in the stem- mother (Colonici) stage, the insect remaining on the 

 branches or, in the case of young trees, on the upper part of the main stem, with her 

 long proboscis buried in the cambium layer of the tree. The insects generally occupy 

 crevices of the bark. 



The stem-mothers must awake into activity very early in the year and oviposit, for I 



