30 REPORTS OF OBSERVATIONS AND EXPERIMENTS. 



green oak, Quercus agrifolia. These caterpillars are not common in the 

 valleys, but along the mountain sides they are sometimes very abun- 

 dant, and I have found them at an elevation of nearly 5,000 feet. So 

 far as at present known, they attack only the various kinds of oak. 



So far as I have observed, these caterpillars do not spin a web or 

 tent in which to live at any period of their lives. The cocoon is of a 

 pure white color, and the powder with which its meshes are partially 

 filled is also white, and not yellow, as in the two preceding species. 

 The loose silk spun about the cocoon is scant, and is much coarser and 

 stiffer than that of the preceding species. The cocoons are spun in 

 May and June, and the moths issue in June and July. Two male and 

 four female moths which I bred all issued from the chrysalis after 5 

 o'clock in the afternoon. 



Three different kinds of internal parasites are known to me to attack 

 the caterpillars of this Glisiocampa. On the 5th of July, 1891, two 

 Tachina flies issued from some of these caterpillars in one of my breed- 

 ing cages; these flies are known as Masicera frenchii Will., hitherto 

 reported only from Maine, where it attacks the larvaa, or chrysalides, 

 of a large butterfly, Papilio turnus var. glaucus* Under a high power 

 the eyes of this parasite are seen to have a few microscopic hairs. 

 Heretofore it has not been reported west of Colorado. I have bred a 

 closely related species, Masicera archippivora Kiley, from the chrysa- 

 lides of two kiuds of butterflies, Pyrameis cardui and P. carycc. 



A single specimen of a second kind of Tachina fly was bred in July, 

 1892, from a caterpillar of the above Clisiocampa by Dr. A. Davidson, 

 of Los Angeles, to whom I am indebted for this specimen. It issued 

 from the caterpillar after the latter had spun its cocoon, but before 

 the change to the chrysalis had taken place. 



The third kind of internal parasite which attacks the caterpillar of 

 this Clisiocampa belongs to the family Ichneumonida?, and has been 

 identified as Pimpla inquisitor Say. In the month of June, 1887, six 

 larvse of this parasite issued from one of these caterpillars after the lat- 

 ter had spun its cocoon, and spun their white cocoons within that? of 

 their host; the winged parasites issued during the following autumn. 

 This parasite is very widely distributed, being found as far eastward as 

 Washington, D. C. It infests a great variety of caterpillars and has 

 also been bred from larvse found feeding upon the eggs of spiders. On 

 the 26th of April, 1892, Dr. Davidson bred five specimens of this Pim- 

 pla from some egg-mass; s of the spider, Epeira angulata Clerck. 



AESENIURETED AND SULPHURETED HYDROGEN AS INSECTICIDES. 



ISot being entirely satisfied with my experiments with these two 

 gases in the past, and wishing to test arseniureted hydrogen pro- 

 duced in a different manner than previously employed by me, with 

 a view of discovering a cheaper gas than hydrocyanic acid to be used 

 for the destruction of scale-insects on citrus trees, etc., I decided to 



