CANKER WORMS. 785 



The above numbers of eggs in one hundred egg-masses show 

 an average of about ninety-four eggs to the cluster and vary 

 from thirty-eight to two hundred and fifty-eight. The smallest 

 egg-masses probably each represent one of two clusters of eggs 

 laid by one insect, or possibly the female was devoured by a bird 

 or some other natural enemy before she had finished depositing 

 eggs. 



Eggs laid by females in captivity show a larger number in 

 each mass than those collected from trees. The following num- 

 bers of eggs were laid by females collected November 20th, 1908 : 



2,299 1,806 1,841 1,593 2,079 



Thus these sixty-five egg-masses laid in confinement show an 

 average of one hundred and forty-eight eggs, the smallest contain- 

 ing thirty-eight and the largest two hundred and ninety-two, while 

 those collected from the trees out-of-doors average ninety-four 

 each. It is hard to account for this difference. Still more curious 

 is the fact that the numbers given in the first four columns repre- 

 sent eggs laid by females taken in coitu, and average one hundred 

 and thirty-four to the cluster, while those in the last column were 

 laid by females collected at random on the trees. It is not known 

 whether these were impregnated or not, but the large average 

 of two hundred and thirty-one to the cluster is difficult to explain.^ 

 From a lot containing forty-three females, two laid no eggs and 

 five laid eggs in irregular masses. A lot of fifty-four females 

 had forty-two that deposited a single egg-mass each, eleven that 

 laid two egg-masses, and one that laid three egg-masses. 



