ON IllI'. S]£IJ-:l i 1< )X AXl) HRKJiDlXt. Ob' DESiKAHl.E 

 STRAINS OF BENEFICIAL INSECTS. 



I>v C'liARi.i.s William Mallv. M.S(.. ^^[^.S., l\I,.S. 



Although the writer is not a " parasite entliusiast," tlierc is 

 no .gainsaying the t'aet that the control of the " tinted or cottony 

 cushion scale" (known in Sontli Africa as "Australian Bug"), 

 fccrya l^iirchasi. hy the ladyhird, Noz'i'us cardinalis, is an out- 

 standing illustration of the practical ini])()rtarice of natural ene- 

 niies in the control of insect i)ests. 



On my arrival in South .\frica in k/X), with ver\- few ex- 

 ceptions the i^eople were enthusiastic over the fact that the 

 ■■ Vedalia "' {Noz'iits cardinalis) was living up to its reputation 

 for controlling the " Australian hug." Dr. E. Peringuey. Direc- 

 tor of the South African Museum, however, claimed that the 

 credit really helonged to a South African ladybird. Jul is fwdata. 

 and that Novius cardinalis had been introduced just at the close 

 of the fight, and having an established reputation for the control 

 of the insect pest in question, it was given the credit of the good 

 work done by the South African species. 



Dr. Peringuey's advocacy of the claims of J. fccdata 

 aroused my interest, and I decided to get a colony of each species 

 and breed them side by side for comparison, more especially as 

 I had not had the opportunity of studying live material of either 

 species before coming to South Africa. Novius cardinalis im- 

 pressed me at once as a cjuick, energetic species, .lulls fa-data, 

 though larger, seemed slow and easy-going in comparison. 

 No7'ius cardinalis matured a generation in a month, whereas 

 .lulls fa-data was mucli slower, the published jiccounts in the 

 Cape of Good Hope .Igricultural Jouriial stating that only two 

 generations matured in. a year. For this reason ak^ne it would 

 soon fall far behind Novius cardinalis. Circumstances pre- 

 vented m\- carrying the colony of Aulls fa-data through to ma- 

 turity. l)ut my observations led me to doubt its abilit\- to cope 

 with Iccrya purcliasi in the western portion of the Cape j'rovince 

 as perfectly as did Novius cardinalis. 



I did not record the information given me by Dr. Peringuey 

 at the time, and, to avoid any possible error, I wrote to him on 

 June 4th. 19 14. for his opinion, as to the relative value of the 

 two s])ecies, and received the following reply on June 7th, 19 14: — 



\ On ask nie wliat the ri.'Si)cctiv(.' value of the cocciiielif! heetk's Aulis 

 fa-data (a native) and .\o7'iiis cardinalis (nn inii)orted article) as eliminat- 

 ing factors of the "Australian l)U<>- "' (Iccrya purchasi) has i)een in South 

 Africa, and you quote a conversation _\ou had witli nie on the suhjeel sooji 

 after your arrival in South Africa (1900). 



Well. I will tell you. !iad I heen prone to hask in the shadow of 

 editors of newspajjers, . . . it is i)rol)ahle that the mantle that fell oil 

 Koebele would have adorned my siioulders. i-nr, certainly four or five 

 years before he brought back .\oviiis from .-Xustralia to (California, had 

 enquiries been made here abctut the pest by the American authorities 

 (you will jx'rhaps remember that I was the first entomologist of your 



