191T] ENTOMOLOGY. 465 



deposited by a single female has not been determined ; from 18 to 25 days are 

 required for their incubation, the first of which out-of-doors were observed to 

 hatch on October 2. 



The young larva feeds on the tender tissues of the plant and soon reaches the 

 soft cambium layer. Externally the beginning of feeding can be easily recog- 

 nized by the blackish wet frass that fills the outer part of the egg cavity. 

 Feeding continues until cold weather and commences the following spring as 

 soon as the weather becomes sufficiently warm. 



Pupation begins in the last few days of June and continues throughout July, 

 the pupal period varying from 10 to 18 days, those formed early in July requir- 

 ing only 10 days while those late in July require the full 18 days. Individuals 

 maturing early in the season usually remain in the pupal cells for two or 

 three weeks before emerging, a general emergence of adults occurring the latter 

 part of July. 



It is pointed out that the observations of European workers do not entirely 

 agree with those made in New York State, thus indicating that the life his- 

 tory and habits of this insect are complex and vary greatly. 



Extensive experiments were carried out on large blocks of trees in nurseries 

 in which varying strengths of miscible oils, emulsions, etc., were applied both 

 in the fall and in the spring. Such work carried on during 1913-14, 1914-15, 

 and 1915-16 has shown that carbolineum avenarius, when applied to the 

 trunk to a sufficient height, gives nearly absolute control. A high-grade creo- 

 sote which has been tried in a limited way has also given a perfect control. 

 Carbolineum is not injurious to the hands and can best be applied by dipping 

 cotton waste into the material, then rubbing carefully up and down the trunk 

 of the tree to a height of 4 or 5 ft. It is pointed out that great care should 

 be exercised to see that the base of the tree is well treated and all parts of 

 the trunk well covered. 



Carbolineum gives the bark of the trees a deep-brown color but in no way 

 affects their vigor. While this brownish coloration gradually becomes reduced 

 during the summer, the treated trees can be recognized easily for at least three 

 years after treatment. In the experimental plats treated in 1913-14 trees 

 were not attacked during 1914 and 1915 and only a single larva was found 

 in them during 1916, indicating that they are not readily selected by the fe- 

 males for ovlpositlon, provided untreated trees are available. 



In nurseries the carbolineum should be applied by hand during the latter 

 part of March and the first week in April. This can be most advantageously 

 done just after the trees are pruned. A careful account of the entire cost of 

 treatment in one nursery showed it to average not more than 0.2 ct. per tree. 



Studies of this beetle by Schoene have been noted (E. S. R., 18, p. 957). A 

 3-page bibliography is included. 



Experimental evidence that bark borers are able to kill healthy fir trees, 

 A. Welandeb {Skogsidrdsfur. Tidskr., No. 6-7 {1916), pp. 520-526, figs. 3; 

 abs. in Rev. Appl. Ent., Ser. A, 4 {1916), No. 12, pp. 507, 508).— Experiments 

 reported indicate that Ips typographus is able to kill perfectly healthy trees. 



The bean beetle (Epilachna corrupta), D. E. Merriul {New Mexico Sta. Bid. 

 106 {1917), pp. SSO, pis. 4, fig. i).— This is a report of studies of E. corrupta, 

 a leaf-eating coccinellid or lady beetle which is the most injurious insect at- 

 tacking the bean in New Mexico. Although its yearly damage is estimated in 

 various localities at from 5 to 100 per cent, the author considers an average of 

 10 per cent to be a conservative estimate. The injury is caused by both the adult 

 )>eetles and the larvae eating outright or skeletonizing the leaves. 



The larvae feed on the under surface of the leaves in colonies when they are 

 young, but scatter later. When at all numerous they eat off the lower epider- 



