140 Recent Literature. [j a ^ k 



insectivorous birds have shown that in most cases Pentatomid bugs are 

 eaten at least to the extent of the proportion of their numbers to the 

 numbers of other insects of the same and larger size. Further, it would 

 seem that some birds, like the Crow, possess a predilection for insects of 

 pungent or otherwise strong taste or odor. Careful studies have been 

 made of the feeding habits of about 20 common American birds. Almost 

 without exception Pentatomids (variously referred to as 'stink bugs,' 

 'soldier bugs,' and 'Pentatomids') are included in the diet of each of 

 these birds, amounting on the average to about 3 per cent of all the food." 

 The experience of the division of Economic Investigations of the Biological 

 Survey is all to the effect that human criteria of taste can in no way be 

 applied to birds. Failure in this respect has led to many fallacious state- 

 ments concerning birds, one type of which relates to the bad taste of 

 certain insects. None are more offensive to man than the stink bugs 

 (Pentatomidse). Nevertheless these insects are attacked by a great 

 variety of birds and sometimes large numbers of them are consumed. 

 Taking as a guide the amount of space occupied by cards in the Biological 

 Survey food index, the Pentatomids are more relished by birds than any 

 other family of Hemiptera and what is more surprising, than any family 

 of Orthoptera which certainly rank as staple bird food. Dr. Morrill says: 

 "Thus far no specific observations have been made for the purpose of 

 determining the extent to which birds feed upon the conchuela [that is, 

 Pentatoma ligata]. It is evident, however, that there is some important 

 influence combined with egg parasitism to produce in midsummer the 

 marked reduction in number of these insects observed both in Mexico and 

 in Texas. The egg-parasites effectually check the multiplication of the 

 pest after the month of July, but the diminution in numbers of the adults 

 remains unexplained. In the laboratory, protected from their enemies, 

 the life of the adult conchuela extends over many weeks, 27 specimens 

 collected at Tlahualilo between July 6 and July 10 averaging over two 

 months each. 



"It is inconceivable that the difference between field and laboratory 

 conditions should be so great that, of the insects of the field on July 10, 

 over 60 per cent should die from natural causes before August 1, while in 

 the laboratory less than 5 per cent should die during the same period. 

 Furthermore, if the numerical decrease in question had been due to natural 

 exhaustion of vitality of the adult insects, it would be expected that many 

 dead specimens would have been found in the cotton fields. As a matter 

 of fact, dead specimens were exceedingly rare and the few found gave 

 evidence of having been destroyed by some enemy rather than of having 

 died from natural causes. As has been shown, the decrease in numbers 

 is a general and not a local occurrence, and it takes place without regard 

 to the abundance of food. These circumstances seem to point to the 

 strong probability that birds are the useful agents in the reduction of the 

 numbers of the adults of the conchuela." 



