78 SPRUCE AND LARCH GALLS. 



The eggs, which may reach 120 in number, are placed in small 

 hollows excavated alternately along its two sides. They hatch in a 

 few days, and the larvae begin to construct lateral galleries at right 

 angles to that of the mother. The larval galleries are at first small, 

 but increase in size with the growth of their inmates and soon take 

 an irregular course. The larvae, when full grown, change to pupae in a 

 small cavity hollowed out in the bark at the end of the burrow 

 and appear as perfect beetles in June or July, emerging from the 

 tree by eating out a circular exit-hole from the pupal chamber. Those 

 which hatch from the first-laid eggs are considerably in advance of the 

 grubs coming from eggs laid at the end of the five weeks' task of the 

 mother, whose dead body can be found at the end of the burrow. 

 The borings of the parents are not at first conspicuous, but can be 

 detected later by the dust thrown out from between the scales of 

 bark, whereas the holes made by the exit of the beetles, which are in 

 no way concealed, at once indicate that they have bred in the trunk. 

 The special form of injury done to Pines consists in the boring of 

 the mature beetle into the young shoots for feeding purposes. This 

 is effected by making a lateral hole in the shoot at a distance 

 varying from one to five inches below its tip. This hole becomes 

 marked with a circular ring or collar of exuding resin, and from 

 it there is bored a burrow for about an inch up the pith of the 

 shoot, which is killed, or, if the burrow is only partially completed, 

 crippled. These shoots break off readily above or through the entrance 

 hole, and strew the ground after a high- wind. Their loss, repeated 

 year after year, produces a striking change in the appearance of 

 the tree, which loses its compact crown and becomes " stag- 

 headed," the foliage being thin and scanty, and dead branches sticking 

 out. It is also liable to the attacks of other insects, and to fungoid 



It is to be noted that Myelophilus piniperda never breeds in the 

 shoots where it feeds, and certain cases recorded where it is supposed 

 to have done so are due to a confusion between its larvae and those of 

 Retinia, or of certain other beetles (Ernolius, etc.). 



Spruce-gall Aphis. A peculiar form of injury is that caused by the 

 sucking of the two kinds of Chermes the Spruce-gall aphis, C. abietis, 

 and the Larch aphis, C. laricis. 



On the Spruce the Chermes appear in the spring as short, oval, 

 wingless insects of an ochreous colour, furnished with a bristle-like 

 rostrum. They have passed the \vinter in crevices and under bark 

 scales, and early in April attach themselves each to the base of a young 

 leaf, which reacts by a small swelling. These forms are parthenogenetic 

 females, the foundresses of the colony, and lay a mass of eggs at the 

 spot (generally at the junction of two branches) to which they attach 

 themselves. The larvae hatching, penetrate the surrounding parts of 

 the shoot with their beaks ; the shoot swells as do the bases of the 

 needles, and a growth commonly known as a " Pine-apple gall " or 

 " Spruce-gall " results. This gall somewhat resembles a small Fir-cone 

 about an inch long, with the surface divided into small convex areas, 

 each bearing a short needle-like projection in the middle ; these are 

 deformed needles which, becoming swollen, touch each other on the 

 outside of the gall, but which are separate inside, so that the gall 

 contains a series of cavities or chambers. In these cavities the larvae 



