50 BUI.LETIN 126. 



the end of the first, and so on around. Usually four or five cuts' 

 were suflScient to girdle a shoot. 



It was very interesting to watch so deft and quick a worker as 

 this insect when she was girdling a shoot. She was not easily dis- 

 turbed when once her work was begun. We have seen one ^emale 

 girdle four or five shoots in aU hour in our cages. Of course, the 

 number of tips one insect will girdle, depends upon how many 

 eggs it la5^s. One female in our cages girdled fourteen shoots 

 and was then accidently drowned. A careful examination revealed 

 four more eggs in shoots that she had not girdled, and we found 

 ten eggs in her abdomen ; thus one female is capable of laying at 

 least thirty eggs or may girdle thirty currant shoots. Much dam- 

 age might thus be done by only a comparatively few of the insects 

 in a currant plantation. 



Doubtless the object of the girdling of the shoot above the egg 

 is to cause a cessation of the growth, and thus prevent any injury 

 which might come to the delicate egg or young grub from the 

 vigorous growth which currant tips make in the spring. Yet in 

 spite of this precautionary habit of the mother, many of her young 

 never develop, as we shall see. 



Habits of the borers. — Some of the eggs laid by the insect in our 

 cages hatched out the grubs in about eleven days. The minute 

 borers at once began feeding upon the pith of the stem, and 

 tunneled their way downward in the pith, as shown in the left- 

 hand shoot in figure 19. They seem to feed almost entirely upon 

 the pithy part of the shoot ; often enough of the woody portion 

 remains to sustain sufficient life in the shoot to develop buds all 

 along the sides of the tunneled portion, as shown in figures 18 and 

 19. The excrement voided by the borers remains in their tunnels, 

 filling them full of a dark brownish mass, as illustrated in the 

 same figures. If an injured shoot be split open at any time 

 between June ist and September ist, the borers may be found at 

 work within their tunnels. 



The great mortality a^nong the eggs and young grubs, — Our ob- 

 servations agree with those recorded by Mr. Marlatt (Insect Life 

 VII., 388) in regard to the failure of many of the eggs and young 

 borers to develop. The material sent us in the spring of 1896, in- 

 dicated that not over 15 per cent of the eggs laid the preceeding 



