1 76 Zoology of Colorado 



sound. The beetles are black and yellow; C. basalis has a large 

 black patch at the base of the elytra, including the scutellum, 

 while C. pennsylvanicus has the scutellum black, but the basal 

 part of the elytra entirely clay-yellow. The closely related 

 Lampyridae include the lightning-bugs so common in the eastern 

 states, but not often seen in Colorado. On May 26, 1889, I 

 found Pyractomena borealis at WestclifFe in Custer County, and 

 noted its bright light. I found that I could intensify the light 

 by pressing the anterior half of the beetle between the finger and 

 thumb. Many authors regard the Lampyridae as only a sub- 

 family of Cantharidae, distinguished by having the antennae 

 closer together. 



Of the Erotylidae, which are especially abundant in the 

 tropics, we have one common and conspicuous form, Cypher o- 

 tylus aspersus. It is elongate-oval, nearly three-quarters of an 

 inch long, the head and thorax black, the elytra pale greenish 

 with many small black spots, which are depressed in the middle. 

 I found it breeding in an old pine stump near Allen's Park. One 

 of the most remarkable of all beetles is the Platypsyllus castoris, 

 forming a family Platypsyllidae. The name means flat flea, and 

 it is parasitic on beavers. It was found in 1868 on an American 

 beaver in the Zoological Garden at Rotterdam, but has since been 

 found on wild beavers both in Europe and America. The beavers 

 of the two continents have become sufficiently modified to be 

 considered distinct species, but their parasite has been more con- 

 servative, remaining apparently unchanged. Platypsyllus was 

 first found in Colorado by Ralph Hubbard, on beavers obtained 

 by Alfred Wheeler in South Boulder Creek. 



The Histeridae are usually broad, thick set, shiny beetles, 

 the elytra not reaching the end of the abdomen. They are found 

 in dung and under dead animals. The genus Hololepta is ex- 

 cessively flattened, adapted for living under bark. The genus 

 was added to the Colorado fauna when a specimen of H. fossul- 

 aris Say was found by Georgia Johnson under the bark of a dead 

 cottonwood tree in Boulder, May, 1922. Another peculiar genus 

 is Hetaerius, consisting of small species found in nests of ants. 

 The very smallest species (1.25 to 1.5 mm. long) was discovered 

 at Boulder and named H. minimus by Fall. 



The Silphidae include carrion beetles and burying beetles. 



