BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 
■2: 
the infested area. Over 100 million adults of a gregarious cocoon 
parasite. Microplectron fii*c'f jxinds (Zett.). were reared by the States 
of Maine. New Hampshire. Vermont, and Xew York in cooperation 
with this Division and released throughout the infested region. This 
parasite has become established in many localities in the United 
State-, and according to Canadian reports it is increasing rapidly 
in certain areas in Xew Brunswick. 
DOUGLAS FIR TWIG WEEVIL 
A recent widespread outbreak of the Douglas fir twig weevil (Cyl- 
mdrocopturus longulus (Lec.)) in western Washington, involving 
conspicuous damage to young Douglas firs, called for an investiga- 
tion, and a comprehensive study of the biology and life history of 
this weevil was concluded during the year. It was found that there 
was one generation a year, beginning with egg laying in green twigs 
from August 1 to September 15, but that the adults overwinter and 
lay fertile eggs the second season. Thirteen species of Hymenoptera 
were found to be parasitic on the weevil. Host resistance, competi- 
tion among the larvae, and parasitism were considered as being the 
most important factors controlling the weevil population. It was 
concluded that this weevil is normally of minor importance on Doug- 
las fir but that it may be a potential enemy of plantations, especially 
those on poor sites and gravelly soils. 
DETERIORATION OF FIRE-KILLED DOUGLAS FIR 
A study begun on the great Tillamook burn of western Oregon in 
1938 to determine the role of insects as deteriorating agents and their 
influence on commercial salvage of the fire-killed Douglas-fir trees 
was brought to a close in 1939 when a second fire swept over a lame 
part of this area and left few trees of the original burn intact. 
Where this second fire was especially hot. large numbers of wood- 
boring larvae were killed, but some broods of Asemum survived in 
the heartwood and deep in the sapwood of burned snags. From now 
on only the largest and best trees can be salvaged in the surviving 
logging operations, since wood borers, decay, and repeated burns have 
rendered unmerchantable the bulk of the original 10.000.000.000 feet 
of timber on this tract of 244.000 acres. This study has been of 
great value to the timber operators salvaging the fire-killed timber 
of the Tillamook burn and will be of further value to other logging 
operators who may be faced with similar problems in the future. 
FOREST INSECTS IN PUERTO RICO 
A preliminary survey of insect conditions in the forests and forest 
plantations of Puerto Rico was made in the spring of 1940. In>ects 
were found to be the most important factor limiting the success of 
forestry operations in the islands, particularly with several of the 
most important tree species. For example, the cedro >hoot borer 
(Hypsipyla grandella (ZeLL)) has made ii necessary for the Forest 
Service to give up attempts to use the valuable Spanish cedar in 
reforestation activities. Following the elimination of cedar. thi> borer 
appears to be rapidly increasing in plantations of mahogany. The 
aceitillo seed weevil {Apian martinezi Marshall) destroys about 98 
