Plant Sanitation. 



m 



[January, 1910. 



state during the cold weather months 

 compared with the period passed by 

 them In the rains. The term of life of 

 the adult, on the other hand, to all 

 appearances, is cut short during the 

 cold weather, the insect not living so 

 long at that time as during the height 

 of the season. It has not yet been 

 definitely ascertained how long it lives 

 in this state during summer, but a few 

 individuals kept in captivity at that 

 time, in 1906, live for 2J months and 

 more." 



Mr. Antram's investigations into the 

 subject of the third question proved that 

 there is, a steady retardation of hatching 

 out, commencing from the middle of 

 November and culminating in the middle 

 of January, after which there is a reverse 

 progression of acceleration until the nor- 

 mal period of from eight to ten days is 

 reached towards the middle of March. 

 A chart shows the curve of retardation 

 and acceleration plotted out to intervals 

 of from one to three days. It is a pity 

 that these intervals could not have been 

 made regular ; but the general tendency 

 of the curve is quite clear, and it can be 

 gathered from it that eggs laid in the 

 middle of November hatched in from 

 eight to ten days; by the 16th December 

 the period had risen to fourteen days ; 

 from which date there is a steadily 

 ascending gradient to the 13fch January, 

 when the*period has increased to sixteen 

 days ; after a few slight fluctuations the 

 maximum period of twenty-seven days 

 is reached on the 20th of January. It will 

 thus be seen that the maximum is just 

 three times as long as the normal period # 



By keeping a number of the insects 

 under observation from the time of 

 hatching until the date of attaining 

 maturity, Mr. A.ntram has shown that 

 there is a corresponding lengthening of 

 the larval period during the cold weather 

 months. The maximum period seems 

 to have been reached by the middle of 

 December, and to have remained fairly 

 constant until the end of that month, 

 after which there is a gradual reduction 

 in the number of days spent in the 

 larval stage. It is stated that, during the 

 height of the season, the insect completes 

 its transformations in from ten to 

 twelve days. Incidentally, Mr, Antram 

 has found that the insect "undergoes 

 five moults altogether before reaching 

 maturity or the winged state," — a point 

 in its life-history that had not previously 

 been established in India. While the 

 development of the egg and of the larval 

 period is delayed by the cold weather, 

 the length of life of the adult insect is 

 somewhat shortened. But the total 

 existence of the individual— from the 



time that the egg was laid to the death 

 of the adult insect— is extended, during 

 the cold season, to more than three 

 months. " During the whole of that 

 time the insect is active and feeding 

 except on very cold nights in November 

 and January when it would be shelter- 

 ing inside the bush or in the jungle 

 growing at the loot of the bush." 



It has been known for some time that 

 the Helopeltis insect does not— like so 

 many insects — lay all its eggs within a 

 short period after fertilization. Dis- 

 section reveals the fact that only a few 

 fully formed eggs ate ready for ex- 

 trusion at any one time, though the 

 ovaries are packed with undeveloped 

 ova. But it is rather startling to find — 

 as has now been determined by Mr. An- 

 tram — that a fertilized female may live 

 for seven weeks and deposit, during 

 that period, over 200 eggs. Indeed, one 

 prolific individual, kept in captivity 

 during the rains, laid nearly 500 eggs. 



Another interesting fact, observed by 

 Mr. Antram for the first time, is the 

 actual manner of the laying of the 

 egg. It appears that the insect first 

 punctures the stem with its proboscis 

 and then inserts its ovipositor into the 

 hole so made. 



The author of the circular then gives 

 the results of his investigations as to 

 the positions — on the tea bush and else- 

 where—in which eggs are deposited, 

 when the bushes are not flushing. He 

 observes that eggs may be found in any 

 of the following sites :— 



"1. In the succulent stems, from the 

 base of the first open leaf down almost 

 to that part of the shoot which is not 

 reddening into wood." 



"2. In the midrib of leaves, both 

 old and young, towards the base." 



"3. In the tips of ruptured stalks 

 where green shoot has been plucked off.'' 



" 4. In the tips of ruptured stalks 

 where both old and young leaves have 

 fallen oft' or have been broken off." 



"5. At the base of minute developed 

 and undeveloped buds in the axils of 

 the leaves." 



"6. In the stalks of flowers and seeds 

 on the bush," 



"7. On two different plants growing 

 in the jungle," 



He remarks that " it seems therefore 

 from the foregoing that the insect has 

 no trouble in finding places in which 

 to lay her eggs under almost any cir- 

 cumstances and nothing sort of collar 

 pruning or very hard pruning will do 

 away with egg sites. It goes without 



