THE SQUASH BUG 21 



On the inside, the little parasitic maggot develops at the 

 expense of the tissues of its host. Here it will remain two 

 weeks or more, toward the end of wiiicii time the unfortunate 

 bug will become sluggish and probably die. Then tlie maggot 

 burrows its way out of tlie body of the host, commonly appear- 

 ing through a hole which it makes near the posterior end but 

 in some cases near the thorax. It appears tliat the maggot 

 seeks to penetrate the body wall of the host at a point where 

 the resistance is least. After thus emerging the parasite finds 

 shelter in the soil of the field. Here its outer skin hardens 

 into a brown case, inside of which the maggot changes to a 

 pupa — the quiet stage in which insects undergo the change of 

 form from a larva to an adult. In two or three weeks the 

 pupa again changes into a fly that breaks through the brown 

 case. Thus the life cycle is completed, and the insect is 

 ready to start another round of existence. At least two 

 broods of this fly occur in one season, as our observations 

 show, and perhaps there are more. 



While as a rule but one egg is laid upon one bug at one 

 time, it is not uncommon to find many eggs attached to a 

 single bug. In one case we counted thirt\'-five so attached. 

 They occur upon any part of the body. 



The final eftect of the parasite is to weaken and kill the 

 host, but apparently the latter, when a female, often lays 

 part or all of her eggs before being thus killed. So the actual 

 good done by the parasite is not as great as might easily be 

 surmised. As a matter of fact the precise determination of 

 the benefit man derives from insect parasites is a very difficult 

 matter, and especially so in a case like this. Yet there is no 

 doubt that the number of squash bugs was somewhat reduced 

 by these parasites. 



7^/ie Toad. — The common toad has been generally con- 

 sidered an enemy of the squash bug, being frequently referred 

 to in this connection in articles concerning the pest. We 

 made a large number of observations on this phase of the sub- 

 ject, the most interesting result being the discovery that the 

 odor given oft' by the bugs will actually kill toads if confined 

 in a small open vessel, such as a wide-mouthed bottle. Some 

 of these experiments as recorded in a published letter by Mr. 



