REPORT OX SOME OF TITE BENEFICIAL AND INJURIOUS 

 INSECTS OF CALIFORNIA. 



By D. W. COQUILLETT. 



LETTER OF SUBMITTAL. 



Los Angeles, Cal., November 3, 1892. 



Sir : I submit herewith my annual report for the year 1892. The major portion of 

 this report consists of an account of the beneficial insects sent to me from Australia 

 and New Zealand by Mr. Albert Koebele under your directions. The caring for these 

 insects and the working out of the life history of the most important ones has con- 

 sumed a large portion of my time during the past season. The present indications 

 are that the Orcus australasiw will prove of more benefit than any other of these 

 recently introduced species. 



Early in the season reports were received of the occurrence in destructive numbers 

 of certain kinds of caterpillars or span-worms, in the .counties of Santa Barbara, 

 Alameda, and Santa Clara; and in accordance with your instructions I visited each 

 of these localities, and spent several days in investigating these destructive insects. 

 The species causing the damage in Santa Barbara County proved to be a kind of 

 span-worm w r hich had occasioned considerable injury to the leaves of English wal- 

 nut trees; an account of this pest is given in the following pages. The principal 

 depredator in Alameda and Santa Clara counties proved to be also a span-worm or 

 canker-worm, closely resembling the well known Fall Canker-worm (Anuopteryz 

 pometaria Harr.), but as the moths have not yet issued the species can not be deter- 

 mined at present, but will be reported upon later. 



The Fluted or Cottony-cushion Scale (Icenja purchasi Mask.), is still held in subjec- 

 tion by the Vedalia cardinaJis. Since sending in my last annual report 1 have, at 

 your instance, sent colonies of this useful insect to New Zealand. South Africa, and 

 Egypt, besides sending a large number of colonies to various parts of this State. 



The treatment with hydrocyanic acid gas is coming into more general use and con- 

 tinues to be the most effectual remedy at present known for the extermination of 

 the various kinds of scale-insects. The sheet fumigator, described in my letter to 

 you of March 18, and published in the .June number of 1\m < i LIFE, is more widely 

 used than any other kind, being less expensive and easier to operate than those here- 

 tofore in use. During the present season the supervisors of Eos Angeles County 

 instructed Mr. John Scott, the horticultural commissioner, to purchase seventy tents 

 and the necessary chemicals, and to fumigate the infested trees at cost to the owners. 

 The city of Riverside has also purchased a large fumigating outfit with which to 

 exterminate any scale-insects that may be introduced there, ami the citizens of Ana- 

 heim, in the adjoining county of Orange, have also purchased a fumigating out tit 

 and have treated nearly all of the infested trees in that vicinity. From the states 

 of Louisiana and Florida I have received Letters in relation to this treatment, and 



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