318 



Smith (H. S.) & Armitage (H. M.). Biological Control of Mealybugs 

 in California. — Mthly. Bull. Col. State Dept. Agric, Sacramento, 

 ix, no. 4. April 1920, pp. 104-158, 1 plate, 28 figs. 



Mealy-bug control in California is a problem that has been extensively 

 studied. As the remedial measures used against other citrus pests, 

 such as spraying and fumigation, are useless against mealy-bugs, a 

 great deal of experimental work in the biological or parasite method 

 has been done, with the result that a solution of the problem has been 

 found, resulting in the saving of several thousands of pounds annually 

 to the citrus industry. This paper gives a resume of the work and of 

 the principles underlying it. 



The mealy-bugs occurring in California include some 35 species, of 

 which the most im])ortant, economically, are Pseudococciis citri, Risso 

 (citrus or common mealy-bug), P. gahani, Green (citrophihis mealy-bug) 

 and P. maHtimus, Ehrhorn (Baker's mealy-bug). [See also R.A.E., 

 A, ii, 434.] The general characteristics and life-history of these 

 species are discussed. During 1918 a species new to California, 

 P. krauhniae, Kuw. (Japanese mealy-bug) was added to the list. It 

 is not at present of economic im})ortance, but might become so in the 

 future if allowed to spread. 



For some years tentative efforts have been made to introduce 

 natural parasites of these species with a view to their control. The 

 *Encyrtid, Tanaomastix ahnormis, Gir., was introduced from Sicily, 

 and has become well established, occurring in almost every locahty 

 where the citrus mealy-bug is found. It was not, however, able to keep 

 the mealy-bug in subjection, and the same miglit be said of the 

 Coccinellid, Cryptolaemus ynontrouzieri, Muls., introduced from Australia 

 but not well established. In 1916, it was found that potato sprouts 

 were excellently adapted for the rearing of the latter beetle in large 

 numbers, and this work has been undertaken with most successful 

 results in control of the Coccids. It is an effective check on all the 

 three principal species of mealy-bug. T. ahnormis prefers P. citri 

 and P. krauhniae as its hosts, particularly the younger stages of the 

 former, and will occasionally oviposit in P. maritimus. The life-cycle 

 of this parasite occupies from 25 to 45 days, and from 1 to 100 eggs 

 may be laid in a single mealy-bug, though one is the normal number. 

 The Coccinelhd, Hyperaspis lateralis, is apparently a native of California 

 and is widely distributed in the State. Its chief host is P. citri, but it 

 has the disadvantage of being hyperparasitised, and is less easily 

 reared than C. montrouzieri. The same may be said of the lacewings, 

 of which several species are predaceous, SympJierobius calif ornicus 

 being a natural enemy of P. citri, P. maritimus and P. krauhniae, and 

 S. barberi of P. citri and P. inaritimus. The Dipteron, Leucopis bella, 

 destroys many eggs, particularly of P. gahani and P. maritimiis. 

 Other insect enemies of less importance include Rhizobius ventralis, 

 several species of Scymnus, the Syrphid, Baccha lemur, Chrysopa spp. 

 (oreen lacewings), but none of these has been reared on a large 

 scale. 



The method of rearing and distributing C. montrouzieri is described 

 in detail, and also the buildings and equipment constructed for the 

 purpose. 



