8 



Each maggot furnishes subsistence for but a single parasite. Adults 

 were bred from resin masses of both the hemlock and the lowland fir 

 bark maggots. 



Eutelus flavipes Walk, is one of the small chalcidid flies. The 

 females have dark metallic-green bodies, cherry eyes, light brown legs, 

 rather dark antennae, and are about 0.12 inch in length. The males 

 are smaller, about 0.08 inch long, and have a broad yellow band across 

 the abdomen. Their bodies are a lighter green and the legs and anten- 

 nae are yellow. Each maggot supports a number of parasites, usually 

 about a dozen. The pupae are formed in the body of the host in the 

 outer resin mass. The adults emerge during the latter part of June. 

 This species was bred only from the hemlock resin masses. 



These two parasites were the only natural enemies found. There was 

 no evidence of any bacterial or fungous disease, and the maggot is so 

 concealed in the bark and resin that it is well protected from preda- 

 ceous enemies. 



ASSOCIATES. 



Two small pill beetles (Amphicyrta simpUcipes Mann, and Simplocaria 

 nitida Mots. ) were frequently found on and near the resin masses. Their 

 relation, if any, to the syrphid was not determined. 



METHODS OP PREVENTING LOSSES. 



Since the black check is the result of the work of the insects during 

 past years, or even centuries, and is thus distributed all through the 

 wood of the trunks of the matured affected trees, the only methods 

 which appear to be available for preventing losses are : 



(1) Where clear stuff is required, select timber which, as indicated 

 by the absence of the old resin masses on the bark, is free from the 

 trouble. 



(2) Utilize timber from badly affected trees for box material and 

 other purposes where the checks are not objectionable. 



(3) Utilize the bird's-eye or curled wood for natural-wood finish. 



BARK MAGGOTS IN OTHER TREES. 

 THE LOWLAND FIE BARK MAGGOT. 



In 1903, while studying the black check of the hemlock at Satsop, 

 Wash., a similar trouble was discovered in the white or lowland fir. 

 The insect causing it was reared and proved to be Cheilosia hoodianiis 

 Bigot, a species closely related to the hemlock fly. The maggot is very 

 similar in size, appearance, and habits. The adult is a trifle larger and 

 not so dark in color. The thorax is dark brown, and the abdomen a 

 light chocolate. The emergence of the adult takes place a little later 

 in the season than that of the hemlock species. Most of those reared 

 emerged about the middle of May, but the last one did not come out 

 of the resin mass until August 12. 



