198 



Aphids. Maize is planted in April and May, and a very heavy infesta- 

 tion of this crop occurred in May. Adults of native Hippodamia 

 convergens passed the winter in the valley and appeared in the barley- 

 fields in February. The presence of a few larvae at this time showed 

 that breeding and oviposition began very early in the year, and may 

 have been continuous throughout the winter. At no time were the 

 native beetles sufficiently abundant to limit the number of Aphids 

 to any appreciable extent. The native species is, however, extremely 

 proHfic, 8 females depositing an average of 334 eggs, while the life- 

 cycle occupied from 17 days in May to 30 during February-March. In 

 captivity, adults and larvae readily devoured Aj)his maidis, A. jjseudo- 

 brassicae, Myzus persicae and Acyrthosiphon (Macrosiphum) pisi. 

 Imported colonies of H. convergens under normal conditions proved 

 slightly more prohfic than the native species. Individuals that had 

 been kept in cold storage at 31° and 43° F., for eight weeks or more 

 were not very successful and were of impaired vitality ; those released 

 after six weeks or less in cold storage were sluggish for a few days 

 and then became normal ; those released from a temperature of 

 58° F. became active immediately. It was found impossible to confine 

 the liberated beetles to a given area, even if heavily infested with 

 Aphids, owing to the rapidity with which they dispersed upon libera- 

 tion ; it is therefore obvious that some time must elapse before the 

 maximum benefit can be expected. Observations upon the value 

 of this method of control are being continued. 



CoNDiT (I. J.). Insect Pests of the Avocado. — Mthly. Bull. Col. 



State Coinmiss. Hortic, Sacramento, viii, no. 1, January 1919, 



pp. 27-29, 4 figs. 

 Cahfornia is fortunately free from the more important insect pests 

 of avocado found in other countries. Minor pests that occur include 

 the Bostrychid, Polycaon confertus, Lee. (twig borer), found burrowing 

 shallow tunnels in small trees, weakening the branches until they 

 were easily broken off. Injured branches should be collected and 

 burnt. On larger trees the pest might become serious, but this is 

 not considered a likely contingency owing to the large range of both 

 wild and cultivated food-plants of this beetle. The June beetle, 

 Serica alternata, does some injury to the foliage. A thrips, Heliothrips 

 haemorrhoidalis, Bch., causes spotting of the leaves and also of the 

 fruit. A tobacco spray would probably control it. The citrus mealy 

 bug [Pseudococais citri] has been noticed infesting avocado trees, 

 being most plentiful on the fruit stalks, and on the twigs in the axils 

 of leaves, etc., and occasionally becoming a serious pest. Another 

 injurious insect found on avocado is an unidentified miner, the galleries 

 of which have been observed in the bark of tender branches in various 

 parts of southern Cahfornia. The removal and destruction of infested 

 branches is advocated. 



Maskew {¥.). Quarantine Division. Reports for the Months of 



October and November, 1918.- MtJily. Bull. Col. State Commiss. 



Hortic, Sacramento, viii, no. 1, January 1919, pp. 30-33. 



The following insect pests were intercepted during October and 



November : — -From Central America : Pseudococcus spp., Aspidiotus 



cyanophylli and Chrysomphalus scutiformis on bananas. From Chile : 



