150 PARASITES OF GIPSY AND BHOWN-TAIL MOTHS. 



As may be noted by reference to the table, the imported parasites 

 are beginning to become sufficiently abundant so that parasitism by 

 them will compare favorably with that by American species, but are 

 not as yet so abundant as to exceed the American species in relative 

 effectiveness. The table as presented does not indicate at all accu- 

 rately the actual status of the several species of parasites mentioned, 

 on account of the difference in the condition of the material at the 

 time of collection. 



Compsilura, for example, is much more apt to leave the cater- 

 pillars before they spin for pupation, and the same is true of Meteorus. 

 Monodontomerus, Pimpla, Theronia, etc., never attack caterpillars 

 before spinning, and Monodontomerus and Theronia frequently 

 reserve attack until some little time after the host has pupated. As 

 it stands, parasitism by Monodontomerus is about equal to that of 

 Theronia and in excess of that by Pimpla or Anomalon. Parasitism 

 by Compsilura is distinctly more effective than that by all of the 

 other native tachinid parasites of the caterpillars. Meteorus is much 

 more common than indicated in the limited territory over which it is 

 now known to exist, and the specimens reared represented the second 

 generation of adults to develop upon the brown-tail moth in 1910. 



Apanteles lacteicolor Vier. is not represented in these collections, 

 since it does not attack caterpillars so large as those involved. 



In carrying on this work several styles of rearing cages were used, 

 of which one was devised for the special purpose of securing the 

 tachinid parasites with the minimum of exposure to the effects of 

 the irritating hairs of the brown-tail caterpillar. This worked very 

 satisfactorily, and since it may possibly be found of service in con- 

 ducting similar work elsewhere, the following description is presented: 



The basis of this cage (see fig. 10) consisted of a box of stiff paste- 

 board 8 inches square and 12 inches high. About 4 inches from the 

 top a stiff paper funnel (a) was fitted and held in position by the 

 cleats (b), which, in turn, were fastened to the sides of the box by 

 broadheaded upholsterer's tacks driven in from the outside. These 

 cleats served to support the tray (c), which just fitted into the cage. 

 The bottom of this tray was covered, in some instances with coarse 

 mosquito netting, and in others with a wire screen of i-inch mesh. 

 Two holes in the side of the tray corresponded with two 1-inch holes 

 in the side of the box, and these in turn with similar holes in a wooden 

 strip (d), which was fastened on the outside. When the tray was in 

 position, paper cones (h) and large glass tubes (g) were inserted in 

 these holes. 



The stiff paper funnel (a) had its apex inserted into another hole 

 bored diagonally in a similar wooden strip which was fitted in the 

 bottom of the cage. Inside of this hole a stiff paper cone (formed 

 like h by rolling up a section of a strip of paper cut to a circular 



