THE MONTHLY BULLETIN. 



449 



Fig. 140. — The larva of 

 Delphastus catalinw. 

 Enlarged. (Original.) 



A few weeks later Professor Watson wrote us that the ladybirds were 



laying eggs and had already gone through a generation in his laboratory. 



Just what will come in a practical way from the introduction of this 



ladybird into Florida is a matter for conjec- 

 ture. As a general proposition not much can 

 be expected from natural enemies which are 

 not specific enemies of the pest to be con- 

 trolled. This is not so true, however, of 

 predators as of parasites, since they have no 

 close physiological interrelations with their 

 liost, and the fact as mentioned above, that the 

 ladybird under discussion feeds only upon 

 white flies but is still general enough in its 

 food habits to enable it to thrive on different 

 species of that family leads us to the belief 

 that the experiment is at least well worth 

 attempting. 



There is another important consideration in 

 this connection and that is that so far as we 

 have been able to determine Delphastus will 

 become a new element in the faunal complex 

 of which the citrus white fly forms the 

 central part. We have seen no record of 

 similar species feeding upon the white fly 

 in Florida, although Mr. AVoglum found a 

 related form, Cryptognatha flavescens, feed- 

 ing upon the citrus white fly in India. In 

 general, the introduction of predators and 

 parasites which have counterparts in a new 

 region is of little value, while the introduction 

 of new species which form a new element 

 always has great possibilities. The reason for 

 this is that in the first case the introduced 

 insects merely replace a portion of the indi- 

 viduals of the local species, while in the second 

 case the local insects are not replaced, but the 

 effectiveness of the introduced species is sim- 

 ply added to the effectiveness of the species 



which already occur in the region and which are of 

 different habits. This phenomenon is easily observed 

 in nature. Reasoning from this standpoint, the 

 introduction of Delphastus into Florida should prove 

 of value. 



Delphastus catalince is a small chestnut-colored 

 ladybird about 1^- mm. in length. The 'legs are 

 bright yellow. The larva is white or yellowish white 

 and covered with rather long hairs. It pupates 

 within the larval skin, generally at the base of the 

 tree, on the bark or fallen leaves, frequently in large 

 clusters. Sometimes it crawls into porous soil. The 



Fig. 141. — The adult of 

 Delphastus catalinw. 

 Enlarged. (Original.) 



Fig. 142. — The egg 

 of Delphastus 

 catalina:. En- 

 larged. (Orig- 

 inal. ) 



pupa itself is white with black eyes. 



