22 THE REPORT OF THE No. 36 



Habits of Young Larvae. As stated previously, practically 100 per cent, 

 of all eggs kept under observation during both seasons, hatched. The only 

 instances of complete sterility occurred where males were not introduced into 

 the cages containing females, for periods of six days after the emergence of the 

 females, and though the latter laid freely, none of the eggs hatched. 



The emergence of all the yowng larvae from any given hatch of eggs, occurs 

 at practically the same time, and usually within 20 minutes all eggs have hatched. 

 The typical action of young larva? on hatching, is to travel in all directions and 

 to rapidly make for the. shelter of rolled up leaves, or to remain quiescent for 

 varying lengths of time on the under side of the leaves on which they were 

 hatched. Observations at intervals of a few minutes, extended over three hours 

 in one case and over two hours in each of three other cases, showed that larvae 

 for some unknown reason sometimes leave the under side 1 of the leaf where 

 they have taken shelter and will come into the sunlight on top of the leaf. 



Soon after being hatched, and during their wanderings over the leaves, 

 many begin to die, some of them just curling up and in a few seconds, dropping 

 off the leaf; others are blown off by the wind and die on the ground; some 

 reach a leaf below and enter the stem at its axil, and others find shelter along- 

 side the mid-rib of the leaf and stay there passively for hours. In three hours 

 after hatching, only nine larvae out of 39 that were seen to hatch from a mass 

 of eggs, could be found on a corn plant under observation; in six hours after 

 hatching, only four larvae could be found. This result was obtained propor- 

 tionately in four cases and only about one-tenth of all larvae that hatched sur- 

 vived the day and passed into the night. The plants on which these records 

 were made had no tassels. When larvae hatch in the immediate neighbourhood 

 of young tassels into which they can readily work their way and find shelter 

 soon after hatching, it is probable that a larger majority of them will survive 

 the first 24 hours. This seemed to be the case in two instances where seven and 

 nine larvae, respectively, all of the same instar, were dissected out of two tassels. 

 First instar larvae readily eat their way into the individual flowers of a tassel; 

 it is usually not until the third instar that they tunnel into the stem of the 

 tassel and cause it to fall over. 



Although the young larvae find their way into some sort of shelter soon 

 after they hatch and do no feeding on the upper surface of the leaf at this time, 

 they have been seen, even half an hour after emergence, to have eaten very 

 shallow areas out of the under surface of the leaf. The work could not be 

 detected by the naked eye, but required a hand lens to show it up. However, 

 by next morning, they had apparently emerged from the shelters of the day 

 before, to eat small easily seen areas out of the top and under sides of the nearest 

 leaves. In some cases these external feeding areas perforated the leaf like small 

 shot-holes, being done the first night and to a lesser extent the following night, 

 but not afterwards. Many observations showed that this injury is done the 

 first part of the season only, when the corn leaves are young and tender and the 

 corn plant not over three or four feet high ; thus later in the season one may find 

 larvae of early instars established in the tassels and upper stem of tall corn plants, 

 and the only visible injury to the leaves is that which was done in the early 

 part of the season to the lowest leaves. Poisoned spray or dust applied at this 

 time may help to control many of the early borers, especially on sweet corn 

 plots. Occasionally larvae of instars later than the second, may be found appar- 

 ently basking in the sun on the surface of leaves or on grass outside burrows. 

 This unusual habit of otherwise nocturnal insects, seems to be the only loop- 

 hole in their behaviour which leaves them open to attack by our common diurnal 



