THE SQUASH LADYBIRD. 17 



The beetle exudes the disagreeable and characteristic odor of the 

 ladybird family, and this undoubtedly serves as a measure of defense 

 agaiust predatory birds and other enemies. 



SUMMARY OF THE LIFE HISTORY. 



The life history of this species as at present known, from the District 

 of Columbia northward, may be summarized as follows : 



The insect hibernates in the adult condition under bark or other con- 

 venient shelter and appears abroad some time in May or June, the date 

 being subject to considerable variation in different seasons as well as in 

 locality. Egg deposition has been observed in the latter part of June, 

 and there is evidence that eggs are deposited also much later. They 

 hatch in from six to nine days and the larvae begin to feed at once 

 upon the leaves, causing them to wither and die. The exact number of 

 molts of the larva has not been ascertained, but there are evidently 

 either four or five larval periods. The larva attains full development 

 in from two to four weeks, ceases feeding, and attaches itself by its 

 anal extremity to a leaf, and next day sheds its larval skin, which is 

 pushed down toward the end of the body, when the pupa stage is 

 assumed. The larva matures any time from the middle of July to 

 near the middle of September. In the pupa state the insect remains 

 from six to nine days, when the pupal skin separates down the back 

 and the perfect beetle emerges, the new brood appearing as early as 

 the last week of July. After feeding for some time the beetles disap- 

 pear for hibernation, the date of disappearance beginning about the 

 middle of September, although individuals are occasionally found later. 



ECONOMIC STATUS. 



Compared with three-score or more of other species of our noxious 

 insects, the squash ladybird is hardly entitled to more than secondary 

 rank. That it is capable, when present in sufficient numbers, of 

 inflicting severe injuries can not be gainsaid, but published records 

 and, more especially, recent investigations go to show that it is only in 

 exceptional seasons and in rather limited areas that the inroads of the 

 larvre and beetles upon the foliage of cucurbits result in material loss. 

 Some reasons for this may be adduced : First and foremost, the species 

 is not particularly prolific. Most injurious insects produce several 

 generations a year. With the present species there is no indication of 

 more than a single brood annually. Second, all stages of the insect 

 occur freely exposed on the plant, and as all are large and conspicuous, 

 they are subject to the attack of other insects and other natural 

 enemies. In spite of the so-called u warning colors" of this insect and 

 of the obnoxious fluid it exudes when disturbed, we know that it has 

 two insect enemies, and probably has several more. Third, the genus 

 is, or at least was, a tropical one, and the species probably reaches its 

 highest development in or near the Torrid zone, and, like other tropical 

 13S92— No. 19—2 



