24 THE REPORT OF THE No. 19 



Tlie work of the economic entomologist only begins witli the identifica- 

 tion of the insect. This step is simply a means to an end. Now, he is called 

 upon to exercise his proper function as an interpreter and to render an 

 opinion as to the nature of the insect. His prognostication depends upon 

 several factors, the most important of which is a knowledge of the insect 

 and its previous history in the locality under consideration. This is of much 

 service in the case of well known insects but of comparatively little value 

 when an unusual outbreak occurs. Then he must fall back upon his 

 knowledge of the general habits of the group, supplemented in not a few 

 instances by an understanding of the local conditions. Furthermore, he must 

 take into consideration the influence of climate and the likelihood of parasites 

 being abundant enough to check an outbreak in its incipiency. Recommenda- 

 tion naturally follows prognostication and is determined in large measure 

 by the previous findings. It frequentfy happens that, owing to the nature 

 of the crop infested or the character of the outbreak, direct control measures 

 are impossible. An intimate knowledge of the possibilities may result in 

 a different rotation of crops being advised or modifications in culture. The 

 wisdom of applying direct insecticides, such as the internal poisons or those 

 destroying by contact can be determined only by a variety of conditions. 

 We must take into account the time of year, the condition of the crop, 

 particularly if it be fruit, and the recommendations may not only vary from 

 year to year but be widely diverse in different seasons of the same year. 



The Bark Borers are extremely interesting forms and we propose to 

 discuss a number of species very briefly because of the most admirable records 

 they give concerning the identity of the form responsible for the mischief, 

 the time when the injury was inflicted, the sequence of the species working 

 in the bark and a variety of interesting biological data, all of which may be 

 gleaned by a study of their workings. 



The small, pale, yellowish, gummy exudations on the limbs of peach 

 trees are very suggestive of the Fruit-tree Bark-beetle (Eccoptogasfer 

 7'ugulosus, Eatz.). It is only necessary to make an examination and find the 

 circular exit holes or to disclose the characteristic galleries lying beneath , 

 the bark, in order to confirm our suspicions. The early work of this insect is I 

 very beautiful, showing the longitudinal gallery made by a single female 

 and the numerous, more slender larval tunnels, the latter increasing in size 

 with their length and ending in a pupal cell. This species is occasionally so^ 

 abundant in New York State as to literally destroy the inner bark and 

 thickly score the sap wood. This illustration shows such a condition and 

 also represents the work of a wood-pecker. This bird not only removes the 

 outer bark in its search for the grubs and pupse, but frequently splinters the 

 wood in its eagerness to secure such delicacies. The Hickory Bark-borer 

 (Scolytus quadrispinosus , Say) is related to the preceding and has a very 

 similar method of operation. The female enters at one point, continues her 

 gallery with the grain of the wood, depositinfr esrgs on either side. The 

 larval galleries diverge therefrom as in the preceding species. It is com- 

 paratively easy to estimate the prolificacy of on individual bv counting the 

 larval burrows originating from the tunnel of a female. This species is 

 occasionally vpry in.i'urious to hickories in New York State. Thp Eed Cedar 

 Bark-beetlp (PhJop.tinvx rlcvfatus. Say\ thouo-li rarely abundnnt enouQ'h to 

 cause material iniury, is extremely interesting because of thp beautiful and 

 very characteristic galleries it makes in its food plant. Thpre is almost 

 invariably a three-lobed chamber at the point of entry, while the long, 

 slender larval tunnels, just grazing the white wood, present a s+rono- con- 

 trast to the dark brown bark delimiting their marsrins. Most interesting of 



