NATURAL COKTEOL. 47 
list of the birds occurring in the beet fields, which have been 
proven to be insectivorous.^ Those marked (*) were especially 
abundant: 
Killdeer (Oiyechus vociferus). 
^ Valley quail (Lophortyx californicus vallicola). 
Western nighthawk (Chordeiles virginianus henryi). 
Ash-throated flycatcher (Myiarchus cinerascens cinerascens). 
* Western meadowlark {Sturnella neglecta)? 
* Brewer's blackbird (Euphagus cyanocephalus). 
* Native sparrow. 
* California shrike (Lanius ludovicianus gambeli). 
Next to the birds as insect destroyers can be ranked the predaceous 
beetles belonging to the family Carabidse, or ground beetles. Only 
two were noted, Calosoma canceUatum Esch. and C semilseve Lee, but 
these proved to be important factors in the control of the beetles. 
Both of these occurred commonly throughout southern Cahfornia. 
Sometimes as many as 15 to 20 would be noted in a single collecting 
trip. Calosoma canceUatum occurred in the greater numbers. 
These predatory enemies are able to dispose of a large number of 
adults daily, as many outdoor observations proved. In one instance 
the examination of a large beet gave 31 live elaterids, 1 0. cancel- 
latum, and the remains of 117 elaterids. This beet had been exam- 
ined just two days previously, so this represented not more than two 
days' work. The rapidity of the work may be judged from the fact 
that the remains of a dozen of the elaterids were still moving their 
legs feebly when discovered. 
The carabids in feeding never touch the head or thorax, but bite 
off all or a part of the abdomen. As the abdomen, except when filled 
with eggs, contains little food it is readily understood how these 
ground beetles are able to destroy so many elaterids a day. The 
carabids did most of their feeding while the elaterids were in their 
secondary hibernation or early feeding period. They were especially 
valuable at this time, as they could dig under the beets and destroy 
the beetles collected there. 
These predaceous enemies — carabid beetles and birds — make a very 
good combination, as the beetles are an effective check early in the 
season, and later, when the elaterids are moving through the fields, 
the birds are at their best. 
Sudden and very severe storms probably act as further checks, but 
in a mild year, such as 1912, vexy few beetles were found to have been 
killed in the field. The adults are also attacked by a fungous dis- 
ease. This disease works well under laboratory conditions, but less 
1 See Senate Document No. 305, 62(i Congress, 2d Session, p. 14, 1912. 
2 Mr. Bryant, in the Pomona Journal of Entomology, vol. 4, No. 3, speaking of the western meadow- 
lark, says, "Ground beetles are taken each month of the year." He then names Limonius californicus 
among those taken. 
