44 8 



The Genus Chermes. 



[sept., 



Graphically the life history of Chermes strobilobius Choi, may be 

 represented as on p. 449. 



The foundress larva of Chermes strobilobius * Kalt. hibernates on 

 the bud, and a gall results, small, stunted, round, and cone-like. The 

 gall is without marked projecting needle-tips, i.e., the needles of the 

 bud broaden out to form the scale-like parts of the gall. The gall 

 ends the shoot, or at most there is a small tuft of needles beyond it. 

 The colour of the gall is yellowish-white. On its outside many sucking 

 larvae can be found. The gall may be ripe by the middle of June. 



The adult C. strobilobius Foundress is red-brown in colour, and has 

 long strands of hanging wool; the eggs are dirty-green. The adult 

 Migrants of Generation 2 are red-brown or dark red, almost black 

 on the upper surface at the front end ; they show on thorax and 

 abdomen two lines of woolly secretion. The adults measure in length 

 1*25 mm. to 2 mm. 



The Colonist larvae, found on the needles of the larch in summer 

 and early autumn, hibernate on the bark of the larch. These Colonists 

 on the larch are distinguishable from the foundress larvae on the Spruce 

 by the fusion of the glandular plates on head and thorax into a sort 

 of chitinous shield, and by the absence of wool. The adult Colonists 

 at the base of the dwarf-shoots of the larch are bronze-brown in colour, 

 and are bare of wool; each lays a large number of brown or green- 

 brown eggs. 



The two parallel series of Generation 4 are the Exiles and the 

 sexuparce, and these, when young, suck on the larch needles, and 

 cause them to knee or bend. These young are dark in colour — blackish 

 or brown — and have no woolly secretion. 



The adult Exiles are dark brown in colour; they secrete a marked 

 white wool, under cover of which their green-brown eggs are laid. 

 The adult sexuparce are winged, and resemble their grandmothers of 

 Generation 2, but are smaller and have a brown-white wool. Of 

 Generation 5, on the needles of the spruce, the males are olive-brown 

 and the females orange-yellow. 



Life History of Chermes lapponicus Chol. 



Just as previously we had in C. abietis Kalt. a species allied to 

 C. viridis — which confined itself to Spruce — so Cholodkovsky distin- 

 guishes a species C. lapponicus allied to C. strobilobius, but confining 

 itself to the primary host Spruce. 



The galls of C. lapponicus are similar to those of C. strobilobius, and 

 the insects of the two alternating generations can scarcely be distin- 

 guished from the same two generations of C. strobilobius. 



Of the foundress generation of C. lapponicus Cholodkovsky distin- 

 guishes two varieties, one whose galls open early and one where the 

 galls open late. 



Distinction between Species. 



It has been stated earlier that distinctions between Chermes species 

 are very difficult. A helpful means of distinction is found in the 

 comparison of the hibernating foundress larvae. 



* C. strobilobius Kalt. is the C. coccineus Ratz. in part, and C, laricis Ratz, 

 of the books. 



