78 CIRCULAR 16 8, U. S. DEPARTMENT OF AGRICULTURE 



DISCUSSION OF THE TEA INSECTS 



The bombycid Andraca bipunctata (172) is a well-known pest 

 of tea and is now distributed throughout Taiwan. It extends also to 

 China, the Dutch East Indies, and India, in the last-named country 

 being a very serious pest in the extensive tea-growing sections of 

 Assam. In Taiwan there are three broods a year, and the short winter 

 period is passed in the pupal stage, the cocoons being found among 

 rubbish on the ground or in protected places on the stem of the plant. 

 The adults of the first brood appear in late February and March, those 

 of the second in May, and those of the third from late August to 

 October. A curious condition commented on by Shiraki is that the 

 early adults of this last generation, those emerging during August 

 and September, never produce eggs, the species being perpetuated 

 solely by the late-appearing individuals. The eggs are laid in com- 

 pact clusters of from 15 to 72 in a single layer upon the under sides 

 of the leaves, each female depositing a total of from 50 to 150. 



The eggs hatch in from 8 to 10 days, and the young larvae, which 

 are very gregarious, begin feeding upon the foliage. They feed 

 during the night, the younger stages resting during the day on the 

 under sides of leaves, while the more mature ones rest on the twigs. 

 In the early stages only the lower epidermis is eaten, but later feed- 

 ing is at the leaf margin, and the bushes are often completely 

 stripped. The larvae are most abundant and injurious during May, 

 June, and July. The larvae of the second brood, which are active 

 during June and July, are attacked very seriously by several unde- 

 termined bacterial diseases and a tachinid fly, and the combined 

 effect of these is often sufficient to cause the almost complete dis- 

 appearance of the insect at this time. When this does not occur 

 extensive areas are completely defoliated, the yield being conse- 

 quently greatly reduced, and with such defoliation for two successive 

 years the bushes wither and may die. The most effectual method of 

 control is the collection by hand of the larvae of the first brood, and 

 this practice is quite general in the tea gardens. 



Euproctis conspersa (172) , which is found in all the tea-growing 

 sections of Taiwan and in Japan, often causes complete defoliation. 

 In the early stages feeding is upon the lower epidermis only, but 

 after the third molt the entire leaf tissue except the midrib and 

 main veins is consumed. There are two color forms among the lar- 

 vae and adult males. The generations overlap considerably, but the 

 general life cycle covers a period of about two months. The eggs 

 are laid on the under side of the leaf in the same manner as by other 

 lymantriids, and these hatch in about 10 days. The newly hatched 

 larvae are gregarious, but become solitary in habit when more ma- 

 ture. The only method of control thus far practiced is the hand 

 picking of egg clusters and larvae. 



Homona menciana (172) , at times very destructive in Taiwan and 

 occurring also in Japan and China, occasionally causes losses 

 amounting to more than 50 per cent of the crop, the greater part of 

 the damage being done during February and March. The out- 

 breaks are sporadic, though heavy infestations occur every year in 

 one or more sections, and in some localities there is great loss year 

 after year. The web formed by the larvae may inclose an entire 

 shoot, thus rendering it unfit for plucking. One month is required 



