244 Variation in the Mealworm, Tenebrio molitor 



long, 0'5 to "75 mm. broad. Through the simple way in which the 

 deposited eggs could be gathered and counted the following facts could 

 be ascertained : 



a. When both sexes of beetles, after development of their adult 

 coloration, are brought together, the first eggs may in most cases be 

 gathered within 8 days. By way of exception this time is reduced to 



1 or 2 days, or may be extended to a fortnight. If after a fortnight no 

 eggs are deposited it is almost certain that no fertilized eggs will be 

 obtained. This sterility of the beetles is sometimes very annoying, 

 especially when one wishes to breed rare variations. Fortunately it is 

 exceptional, though not so very rare. 



h. The ability to produce a larger or smaller quantity of eggs is a 

 highly variable character, the average figure of which could be only 

 determined from a great number of experiments. From one female 

 30 eggs as a minimum, 359 as a maximum were obtained. A normal 

 harvest gives 100 — 150 eggs. 



c. No regularity or periodicity in the egg-production could be 

 ascertained either in the quantity laid in a day, or in a definite period 

 of days. Sometimes eggs can be gathered daily during a week, some- 

 times a period of 2 — 14 days passes between two succeeding gatherings. 

 Even if the numbers of eggs obtained during periods of 5, 10 or 15 

 days are compared, the figures show nothing that would point to any 

 regularity. 



d. The duration of the egg-production is also very irregular and 

 varies between 50 and 130 days. Normally the gathering will last 



2 months before egg-production ceases. 



3. Duration of Life of the Sexes. 



The male does not live so long as the female. When only one pair 

 is brought together the cT is usually killed by violence and eaten by 

 the $ , often in such a manner that only a few remains of the chitinous 

 organs are recovered. When the $ has filled her vesicula seminalis 

 with sperm, and she no longer needs the </ for the fertilization of her 

 eggs, she seems no longer to care for his caresses, and he is killed. 

 She continues then for quite a long time to produce fertilized eggs. 

 From a series of 32 experiments (undertaken with the view of ascertain- 

 ing the duration of life of the sexes) it appeared, that on an average 

 the male lives 60 days, and the female 111 days. So the $ survives 

 the </• by about 51 days. 



