The data obtained from the females confined ''en masse" show 

 that. — a total of 1,406 females laid 1,560 eggs in an average period 

 of 6.4 days. Or, reduced to the eciuivalents of the preceding table 

 of averages: 



Average from 60 per cent of females, .29 eggs per day, or ] egg each .Si/^ days. 

 Average from all the females, .172 eggs per day, or 1 egg each 5% days. 



INSECT PARASITISM. 



The insects which prey upon this species are the same as those 

 listed for the genus. Probably one of the more important ones is 

 the predacious wireworm, Pyropiiorus luminosus 111., the exact value 

 of which, however, as a control of the grub in the fields it is very 

 difficult to ascertain, from the fact that, in digging or plowing, living 

 wireworms are very rarely found adjacent to the grulis they have 

 attacked. 



Other important enemies of vandinei, in the more northern part 

 of its range, are the two Tachinid flies wliich parasitize the adults. 



As to the large Scoliicl wasp, Campsomeris dorsata Fab., it has 

 been found that on the island of Barbados the species, though com- 

 uionly parasitizing and apparently preferring the Dynastid, Ligyrus 

 tumuJosus Burni., is occasionally found parasitizing a common Melo- 

 lonthid, Phytalus smithi Arrow (18, p. 56). In Porto Rico this wasp 

 is particularly abundant in the Guanica district, where it has been 

 often found parasitizing Ligyrus tumidosiis grubs. It is possible that 

 it may rarely attack grubs of Phyllophaga vandinei; but to the 

 present date none of the records of its attack of this species have been 

 verified; and the fact is patent that, of manj'^ hundreds of grubs of 

 vandinei examined by the writer, and many dozens reared in confine- 

 ment, not one has ever been observed parasitized by egg or larva of 

 this wasp. Dry grul) remains have been examined attached to num- 

 bers of Cahipsomcris cocoons collected at Santa Rita, ])ut none of 

 them proved to be vandinei. 



The Tachinid ffies. — Two species of Tachinid fly, Crypfomeigenia 

 iiarifacies Walton (see PI. YII. fig. 7) and Eutrixoides joicsii Wal- 

 ton, which have l)een previously discussed, are known to attack tliis 

 species and porioricensis in the more humid parts of their ha])itats. 

 and to do nuich to keep tliem in check in those localities. A rather 

 large percentage of specimens of vandinei collected at A fiasco, at the 

 west end of the Island, have been found infested witli the ytwyv^ f»f 

 Crypfomeigenia, and a far smaller number with Eiifri.roidcs. Col- 

 lections of pupae have been made in April, INIay and September, ))ut 

 doubtless can be found throughout the year. The number of pupa- 



86 



