INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 129 



Dolic acid and boil for ten or fifteen minutes. The resulting mixture 

 should be a thick, light, creamy emulsion. For orchard use, 1 gallon of 

 this stock emulsion is added to every 20 gallons of water, the resultant 

 spray being milky -white in color. 



There are several commercial sprays upon the market which the 

 writer has not had an opportunity to experiment with, but many of the 

 growers in California have used them, some with good and some with 

 poor success, as we might expect from the use of any sprays. 



The best time to spray for mealy bugs appears to be during the fall, 

 winter and spring months, between October and March, when the eggs 

 are being laid, the young hatching and the insects are more in evidence 

 than at any other time of the year. At this season the citrus trees are 

 also more or less dormant and are better able to withstand the sprayings 

 than during the summer months. 



Fumigation. — From all the experiments there seems to be a common 

 belief that fumigation is the most efficient and economical means of 

 commercial control in the orchards, and that by repeated applications 

 small infestations might even be entirely eradicated. It has also been 

 demonstrated that a repetition of small doses, one half to three fourths 

 or full schedule No. 1, has usually given as good results with the least 

 injury to the trees as the excessive doses which were thought to be best 

 in the first investigations. In Ventura County the writer obtained 

 good results by using the three fourths schedule No. 1, making a second 

 charge at the end of the first hour, thus using two doses at hourly inter- 

 vals, making the entire exposure two hours. 



Natural Enemies. — There are many natural enemies of the citrus 

 mealy bug. including the hymenopterous parasites (Chrysoplatycerus 

 splendens How., Cheiloneurus dactylopii How.) S1 the ladybird beetles, 

 the mealy bug destroyer (Cryptolannus montrouzieri Muls.) , the two- 

 spotted ladybird beetle (Scymnus bipunctatus Kugel.), Scymnus gut- 

 tulatus Lee, the margined Scymnus (Scymnus marginicollis Mann.), 

 the clouded Scymnus (Scymnus nebulosus Lee), the small brown lady- 

 bird beetle (Scymnus sordid us Horn), the two-stabbed ladybird beetle 

 (Chilocorus bwmlnerus *Muls.) , Hyperaspis lateralis Muls., the black 

 ladybird beetle (Ehizobius rentralis Er.) and Lindorus lopunthus 

 Blaisd. ; the neuropterous insects, the green lacewing (Chrysopa cali- 

 fornica Coq.) and the brown lacewing (Sympherobius angustus 

 Banks) : and the two dipterous insects, Leucopis bella Loew and Baccka 

 lemur 0. S. 



• S, P. H. Timberlake considers this insect as a secondary and not a primary parasite. 



9 — 13664 



