750 FIFTH REPORT OF THE ENTOMOLO(iICAL COMMISSION, 



may be 8oen inclosing the base of the bud and the surrouudiug new leaflets ; but 

 most of them, like E. frustrana, live entirely within the shoot from the moment they 

 have bored their way into it, and undergo therein their transformations. 



The injury done by iJ./rHstrana to the pitch pine {Pinus rigida) of Nantucket is 

 soon detected in the months between May and September by noticing the dead nee- 

 dles at the very tip of a shoot otherwise of a fresh green color, or only partially with- 

 ered near the dead needles. The egg must be laid, as Ratzeburg presumes it to be 

 in the Euroi)ean species, between the scales of the bursting bud, from whence the, 

 caterpillar eats its way at birth into the very heart of the bud near the extreme tip; 

 for to this part are the youngest caterpillars confined. From this point the growing 

 caterpillar burrows down the stem, often for from 4 to 6 centimeters, and thus eats 

 the very life out of the tree ; for with one of these insects at nearly every bud, as was 

 the case in the tree I cut down, and in the accessible branches of many others exam- 

 ined at different times, the tree must speedily perish. As the caterpillar works 

 downward, one by ouo the needles find their supply of nourishment cut off, cease their 

 further growth, lose their color, and wither — the change in coloration of the needles 

 showing the progress of the pest. Fig. 6 shows the appearance of one of these twigs 

 in which the caterpillar has bored a couple of centimeters. Some of the terminal 

 needles, as may be seen by comparison with fig. 5, which represents an unharmed 

 twig of the same ti'ee, have scarcely had a chance to grow at all before being robbed 

 of their means of support, and have turned quite yellow; further down the stem, 

 where also they are wholly withered, they are a little longer; still further they are 

 longer yet, and only partially withered, showing more recent attack; and it is not 

 until the wholly green and fresh needles are reached that they are of the normal 

 length. The difference between an uninjured twig and one that has been attacked 

 is really greater than appears bj' comparison of figs. 5 and G ; for, as will be seen on 

 comparing the lower normal needles of each, fig. 5 represents a shoot with much 

 shorter needles than fig. 6 would normally have had throughout. The dome-shaped 

 contour of the needle tips in the healthy shoots is well represented in fig. 5, and the 

 contrast to this which fig. 6 exhibits is very marked, and tells the story of the dam- 

 age done. The specimen represented in fig. 6 was chosen rather to exhibit this point 

 being perhaps more marked than usual. Generally the whole shoot is unnaturally 

 swollen and disfigured by the pitch that has exuded from the injuries caused by 

 the caterpillars, as may be seen on removing the needles ; this appears in fig. 9 of the 

 plate, to compare with which a healthy shoot with the needles removed is shown in 

 fig. 7. 



As the insect is probably double-brooded, the second generation has to attack 

 shoots already grown or nearly grown, in which case, of course, the change of con- 

 tour of the tip, seen on comparing tig. 6 with fig. 5, does not ensue ; but the withered 

 needles are all of nearly the full length, as shown in fig. 8. In this figure the stem 

 has been cut longitudinally, to show the nature and extent of the borings of the 

 caterpillar. The middle of the stem is found pierced by a slender cylindrical passage 

 as far as the dead needles continue; the passage is lined with silk and foul with ex- 

 crement, which has been removed from the specimen drawn. As far as the boring 

 has been carried the withered needles fall from their position on being touched, hav- 

 ing nothing but a shell for their support. 



When the caterpillar is fully grown it selects a place within its burrow wherein to 

 change to chrysalis; this is usually at the bottom of the burrow, bat in a thick 



doubt of their very close relationship, but the difference in the habits of the larvie 

 in the two localities, both during active life and when about to undergo metamor- 

 phosis, would be very singular if they belong to the same species. The specimens 

 carefully studied by him, also, were found on a difterent species of pine. I have 

 made no comparison, but only desire here to call the attention of those who may 

 hereafter study this insect to this fact. For further account of Mr. Comstock'a 

 observations see the close of this paper. 



