Ui 



I'KOTFXTIOX A(;.\IXsr IXSI-XTS. 



Caterpillar 10 mm. long, with 10 prolegs, dark green, darker 

 on the back, with two brighter green stripes along the sides; 

 head and prothoracic sliield shining black. 



/'. Lifc-]iis((irij. 



The molli ajipoars in August and the beginning of Septem])er. 



The eggs are laid at the base of young larch shoots, and 

 remain over winter. The caterpillars appear in May or June, 

 and pupate at the end of July or in August in a silken cocoon 

 amongst the needles, on twigs or, when the insect is very 

 numerous, in bark cracks, (ioicratioii annual. 



^- 



1 



Fig. I'o.—Tortrix pi 

 colli i/a, 'AW. 



c. Kel//lioHs III (he Forest. 



The caterpillars usually attack only old larch, and chiefl}' 

 sickly trees, but when very numerous 

 they also attack healthy trees, and 

 underwood of spruce or P. C'cmtira 

 growing below the larch. They eat 

 the needles, at first those of the 

 lower shoots, subsequently climbing 

 to the summit of the trees. The 

 insect sometimes appears in such 

 numbers as to comjjletely strip the 

 trees of needles, and entire woods 

 may then appear with a brown 

 canopy, as if the needles had been burned. As a rule 

 fresh needles appear during an attack, but if it should lasl for 

 2 to 3 years, even the healthiest trees will succumb. Badly 

 stocked woods on shallow' soil and with a southerly aspect 

 suffer most of all. 



This insect is common in Switzerland, and has been 

 observed over fairly large tracts of forest in 1855-56-57, 

 18(;4-r)5, 187H-7!) in the Ober Engadin, Wallisand Graubundt. 

 In 187J) in llio Ober Engadin, where larch is the dominant 

 species, over 15,000 acres of forest were attacked ])y it. Also 

 in 1889, in the Tyrol. It is not uncommon among larches in 

 liritain. 



