53 



FiR.I. 0- 



varieties are raised to extend the season; but the " Wilson" is the staple. Unfortun- 

 ately it adds to its many excellent qualities that of extreme susceptibility to insect attack, 

 and of all the varieties grown in New Jersey this 

 only is killed down in a lew years unless carefully 

 looked after. 



I began my studies on the insect pests of the black 

 berry in the early part of the present year, before yet 

 the canes had begun to leaf out, and found that all the 

 pests infested cane or root. 



One of the chief pests is the well known Agrilus 

 ruficollis, or red-necked blackberry cane borer (Fig. 10). 

 Its life history has been worked out by others,and I have 

 nothing of any importance to add. The well-known galls 

 (Fig. 11) usually indicate the position of the borer, and 

 how to get rid of it is the question. I say the galls usually indicate the position ofS|the 

 borer, because, though there can be no gall without a borer, we can have a borer without 

 a gall. If a gall be split the length of the cane it will be seen that the wood is not 

 involved in the gall growth, but only the bark. The insects emerge from the canes iu 

 early summer, May 25 to July 10, the month of June being the time of greatest abun- 

 dance. The egg is laid by the female at the base of a leaf stalk, and I believe it is not 

 thrust into the tissue, but is simply laid at the base of the stalk or in 

 the bud there starting. It was not until late in July that any 

 larvfe were found. The first sign of their presence was a dead bud 

 at the leaf axil, and where the stem was carefully examined almost 

 every dead bud showed traces of having been eaten into, the minute 

 and very slender young larvse being found under the bark near by. 



Usually they run up the main shoot ; but where laterals have 

 become well developed they often go into these, especially where 

 more than one egg was laid in the same place. In neglected fields, 

 often as many as three eggs may be found at a single point, and five 

 leaf axils may be infested on a single stalk. The young larva bores 

 upwards in a cork screw channel in the sap wood, until early August. 

 Some are at that period only one fourth of an inch long and almost 

 nothing in diameter, while others are half an inch in length and 

 reasonably stout. Sometimes a larva will make only two or three 

 long circles around the cane and then, while yet minute, will pierce 

 the cane and get into the pith. Where this is done, no visible 

 gall forms. Others, however, and usually those in large, stout 

 canes will circle the stalk half a dozen times or more in succession, 

 the girdles not more than one-eighth of an inch apart. The first 

 trace of a gall I found in early August, when a slight ridge 

 appears over every larval gallerji, so that the course of the borer 

 is perfectly traceable on a smooth stem. As the cane grows the 

 sawdust and excrement in the galleries seem to swell and enlarge 

 and also to destroy the vitality of the tissues around it, until 

 instead of the girdlings becoming smaller, they really become 

 more prominen:, and the abnormal growth of tissue continues. 

 In some cases, as stated, no galls appear ; but this is somewhat 

 exceptional. In raspberry I have not found the galls, while borers 

 have been found not rarely. This indicates that some of the exempt varieties of black- 

 berries may simply form no galls, I am the more inclined to believe this, because I 

 have seen beetles in no small numbers in "exempt" fields. [ believe, too. that killing 

 the cane is due, not to the injury in the pith, but to the injury done under the 

 bark. Beyond this, the history of the insect is well known ; but I am not aware that 

 the gall formation has been as fully observed. Of course the remedy is obvious. Cut- 

 ting the galls out thoroughly in early spring and burning the cuttings is certain This 

 is already practised by our best fruit growers, and they are not much troubled. Unfortu 



Fig. n. 



