INSECTS INJURIOUS TO AGRICULTURE IN JAPAN 25 



center of the branches, often causing their death. Though the trees 

 attacked are usually those in an unhealthy condition, sound ones may 

 also be damaged. This is one of the most injurious insects upon 

 apple in northern Japan, and it is also recorded as attacking grape. 

 Control measures are largely cultural, consisting of sufficient water- 

 ing and the extensive use of fertilizer; and in addition extensive 

 pruning, with the destruction of all dead wood. It is also suggested 

 that the trunk and larger branches be painted with kerosene emul- 

 sion during June and July to prevent oviposition. 



Scolytus japonicus is recorded as infesting apple and plum through- 

 out Japan, being particularly injurious in Hokkaido. Healthy and 

 vigorous trees are attacked from the main trunk to the twigs 1 inch 

 in diameter. The trees become much weakened and finally die. 



The clear-wing moth Conopia (Aegeria) hector (96) is a very 

 serious pest of various deciduous fruits, particularly apple, pear, and 

 cherry, and is most abundant in Hokkaido. One brood is produced 

 each year, and the winter is passed in the intermediate larval stages 

 in the burrow under the bark. Pupation occurs in midsummer, the 

 adults appearing in August and September. The eggs are laid in 

 crevices in the bark. 



Okamoto and Muramatsu (152) have recently described an addi- 

 tional species of sawfly upon pear in Chosen under the name Janus 

 piri, which is now becoming a Yerj serious pest in some sections. It 

 was first noted as causing damage in 1919. The European pear (P. 

 commwfiis) is much more severely attacked than the Japanese sand 

 pear (P. chinensis). Of the former the Keiffer is relatively lightly 

 attacked and the Bartlett moderately so. When interplanted, the 

 native varieties are very slightly injured and the foreign ones often 

 very badly. The attack is particularly serious upon young trees 

 which it is desired to train to a certain type of growth. A single 

 generation is produced each year, the adults appearing in April. 

 Oviposition takes place in incisions in the young shoots 2 or 3 inches 

 in length. These twigs are then girdled about 1 inch beyond the 

 point where the egg was inserted, causing immediate wilting beyond 

 that point. The larvae, upon hatching, feed in the center of the twig. 

 Late in the season and during the winter the infested twigs may be 

 recognized by the more or less swollen condition at the base. The egg 

 and pupal stages cover 7 or 8 and 8 or 9 days, respectively, and the 

 winter is passed in the larval stage in the twigs. The eggs are laid 

 on warm, sunny days from 10 a. m. to 1 p. m., and usually on the 

 southern side of the tree. Control measures advised are the removal 

 of infested twigs during the winter and early spring and of wilted 

 shoots during April and early May, as these latter contain the eggs 

 and young larvae at that time. 



A lepidopterous borer, Metzneria sp. (#), is recorded as at times 

 causing injury to pear twigs in Chosen. One brood is produced 

 each year, the adults appearing late in April. The eggs are laid at 

 the base of the bud and hatch in 16 or IT days. The young larvae 

 crawl about the twigs for a time and finally choose a suitable spot 

 at which to enter. About 36 hours is required for penetration. 

 Within two weeks the twigs begin to swell at the point attacked 

 and eventually become much enlarged and distorted. The larval 

 stage covers a period of approximately six months, and the winter 



