SPRUCE FIE* — SPRUCE-GALL APHIS. 



267 



gluey matter. This may be made either in a hole gnawed in 

 the bark a little above the root of their food-tree, with wood- 

 dust and chips, or, if nothing else occurs, they will glue any- 

 thing accessible together ; in captivity I have found, a bit of 

 carpet in the corner of a deal-box suits them perfectly. In 

 this cocoon the caterpillar changes to chrysalis, from which 

 the moth comes out in May or June of the following year. 



From the great size of these caterpillars they may be 

 readily got rid of by hand-picking on low trees in nurseries, 

 as soon as the eye of the picker has got used to their 

 appearance. They are not easy to detect at first, from 

 the form and colour of the markings much resembling those 

 of twigs and leaves : when first hatched the caterpillars are 

 stated, except in the case of special varieties, to be almost 

 black. Where attack has been prevalent, examination should 

 be made in autumn as to whether cocoons have been formed 

 on or in the bark of the infested trees, and, if so, the cocoons 

 should be destroyed. 



SPRUCE FIR. 



Spruce-gall Aphis. Chermcs abictis, Linn. 



Winged female, pupa, eggs, and horn, all magnified. Section of Chermes 

 gall in dried state after departure of Chermes. 



The Spruce-gall Aphis, known also as the Spruce Adelgcs, 

 or Spruce Chermes, causes the small bright green, or green 

 and rosy, galls, shaped like miniature Pine Apples (or some- 



