350 MONTHLY BULLETIN. 



of pests, due to the fact that any surplus of parasites is taken up in 

 the spread of the species. Once the insect is thoroughly distributed 

 over the region it is to inhabit, it will increase rapidly in abundance 

 of individuals at any particular point, and then, and not until then, 

 will it become of practical importance. The period of time necessary 

 to wait can be greatly shortened by artificially spreading the parasite 

 and this work the Insectary is engaged in at the present time. — H. S. S. 



Recent Ladybird Introductions. — During the past two months two 

 species of ladybirds, one a scale feeder and one an aphis feeder, have 

 been colonized in California. These were received from Mr. Clausen, 

 assistant superintendent of the Insectary, who is at present in the 

 Orient, searching for beneficial insects. Both species were collected 

 in Japan. The scale-feeding ladybird is Chilocorus simiJis, the same 

 species which was introduced several years ago by the United States 

 Department of Agriculture, but which apparently failed to become 

 established. Its principal food is said to be the San Jose scale, but it 

 feeds upon practically all Coecids, preferring however the armored 

 scales or Diaspinfe. The aphis feeder has been determined as Ptychan- 

 atis oxyridis and is an extremely variable species. It is of large size 

 and is generally black with a large reddish spot on each wing-cover, 

 although it is frequently yellowish with numerous black spots. It feeds 

 voraciously on most aphids and should be of value in their control. 

 Both ladybirds were colonized in Capitol Park, Sacramento. — H. S. S. 



