288 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



oviposit, the females became spent early in the season, which resulted 

 in little or no infestation of beans produced late, but if there were no 

 pods in the early part of the season, the females would merely hold 

 over until pods were available. The above data definitely shows this 

 suggestion not to be the case, because although there were few or no 

 horse bean pods in San Luis Obispo County during the regular egg 

 laying season of 1918, the females were quite apparently unable to 

 hold over and deposit eggs on the later produced pods. 



Therefore, from the figures given in the tables and the experience of 

 San Luis Obispo County, the efficiency of late planting as a control for 

 the horse bean weevil is definitely proved. It should be noted, in 

 passing, that late planting can only be practised where there is an 

 abundance of soil moisture, or plenty of water for irrigation, and in 

 localities where the spring weather is not too hot or dry. 



Since the pea weevil has a very similar life history, will not such 

 methods also apply to it? 



Chairman Quayle : The next paper will be presented by Mr. Harry 

 S. Smith, Superintendent of the State Insectary of the State Commis- 

 sion of Horticulture, Sacramento, California. He will speak "On 

 Some Phases of Insect Control by the Biological Method." 



ON SOME PHASES OF INSECT CONTROL BY THE 

 BIOLOGICAL METHOD^ 



By Harry S. Smith, California State Commission of Horticulture, 

 Sacramento, California 



The biological method of insect pest control, broadly speaking, 

 embraces the use of all natural organic checks, bacterial and fungous 

 diseases as well as parasitic and predaceous insects. The remarks in 

 this paper, however, refer to the use of entomophagous insects only, 

 since the writer has not had an opportunity to make observations 

 on the diseases on insects, and conditions in California do not seem 

 in general to favor their use as means of pest control. 



From a practical standpoint the biological method may be arbi- 

 trarily divided into two sections: First, is the introduction of new 

 entomophagous insects which do not occur in the infested region; 

 and second, the increasing, by artificial manipulation, of the indi- 

 viduals of a species already present in the infested region, in such a 

 way as to bring about a higher mortality in their host than would 



1 Occasional contributions from the California State Insectary, No. VI. 



