136 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



"wool" (Plate II. Fig. 3). These eggs hatch in three weeks, 

 giving two types of larvae, namely — 



(a) Progrediens larvae, which migrate to the needles. 



(^) Sistens larvae, which generally settle round their dead 

 mother and remain undeveloped until the following 

 spring. Some climb on to the needles and perish. 



(4) Sexupara Ge?ieration. — The Progrediens larvae (3 « ) 

 are green in colour, and they feed on the larch needles from 

 mid-May to mid-June. The needles lose their chlorophyll 

 and become bent. The third moult gives the nymph stage, 

 and the fourth the adult Sexupara. This winged female is 

 green in colour and secretes some " wool." The Sexuparae 

 migrate to the i to 3-year-old spruce needles, and there lay 

 about ten yellow green eggs under cover of the wings and a 

 little "wool." It is rare to find them on the needles of the 

 current shoots. 



(5) Sexuales Generation. — The larvae of the males and females 

 hatch in two to three weeks. After four moults they become 

 adult, and the female lays a single fertilised Qgg under a bark 

 scale. This egg is yellow-green in colour ; it hatches in about 

 three weeks, giving a greenish fundatrix. 



There is probably a third species of this genus whose life- 

 cycle consists of five generations which resemble those of 

 Ch. viridis, Ratz. This species, however, possesses both 

 Gallicolae non-migrantes, remaining on spruce, and Gallicolae 

 migrantes, migrating to larch. Borner considered that this 

 species was the only one of this genus, and named it Ch. 

 abietis (L.), Borner, Cholodkovsky considered that it was 

 confined to Western Europe and named it Ch. occidentalism 

 Choi. 



Genus Cnaphalodes (Macquart.). 



Cnaphalodes lapponicus (Choi.). 



The life-cycle of this species consists of two generations — 

 Fundatrix and Gallicola non-migrans — and is passed entirely 

 on spruce. The cycle is completed in one year. 



(i) Fundatrix Gefieration. — The Fundatrices hatch during 

 August, September, and October, from eggs laid by the 

 Gallicolae non-migrantes on spruce. They are reddish-brown in 

 colour at first, and gradually they turn very dark brown. They 



