320 INSECTS AND MAN 



countries great damage is done by a scale insect, Diaspis 

 pentagona, so called on account of its pentagonal form, 

 to various crops, for the insect does not confine itself to 

 one food-plant. An inveterate enemy of this scale insect 

 is a small hymenopterous parasite, Prospaltella berlesei, a 

 near relation of the Indian Prospaltella lahorensis. The 

 parasite was introduced into Italy in 1908, and into 

 Switzerland in 1912, and has now established itself near 

 Locarno. Fortunately, the cultivators and landowners 

 soon learned to look upon the newcomer as a benefactor, 

 so there has been no difficulty in ensuring it a wide dis- 

 tribution. Speaking of the pest and its parasite, Professor 

 E. Voglino says, "The countrymen about Valenza have 

 learned to recognise the parasitised scales perfectly, and, 

 as they all have small properties, they pick out twigs with 

 plenty of scales and their parasites on them at pruning 

 time and take them to fasten on their own trees. In 

 some parts of Venetia the farmers who have material 

 infected by Prospaltella make a regular trade of it, selling 

 twigs of a foot long with sixty to eighty per cent, of 

 parasitised scales for half a lira each." A contrast to the 

 American methods, indeed, this trade in infected twigs, 

 still a step in the right direction, and for that one ought 

 to be thankful. That the trade in these twigs is worth 

 cultivating is evident from the returns of one grower, who 

 from a small lot in 1909 increased his stock to one hundred 

 in the next year, to five hundred in 1911, and to thirty- 

 five thousand in 1912. Hopes are entertained that the 

 parasite will eventually rid Italy and other countries of 

 the harmful scale on which it lives. 



It is impossible here to give a detailed account, or even 

 a resume", of all the attempts, successful or otherwise, that 

 have been made in the transportation of beneficial insects, 

 but two of the apparently unsuccessful experiments may 

 be mentioned on account of their general interest. For 

 a long time the dromedaries in Algeria have suffered from 



