34 INSECTS INJURIOUS TO STAPLE CROPS. 



oval form, flattened below, so that the legs may be drawn 

 in under tlie wing-covers. 



Those Ladybirds which feed upon scales are much 

 smaller and black, though sometimes s^iotted with red or 

 orange. 



As fa,r as known, there is no .way in which these useful 

 allies may be encouraged or increased in numbers, but it 

 is trusted that the above may give such a brief view of 

 their habits that fewer may be killed through ignorance 

 concerning their true Avorth. 



Syrphus-flies. 



Besides the little beetles described above there is a 

 family of flies, the SyrphidcBy many of whose larvae feed 

 upon plant-lice. This family is a very large one, and thus 

 the habits of its different mombers vary considerably. 

 One of them so closely resembles a honey-bee as to be 

 almost indistinguishable from it. The larva of this fly 

 {Eristalis tenax) is one of the common Rat-tailed Maggots 

 which is found in putrid matter. It is thought that the 

 old '^ bugonia " superstition of the ancients that bees came 

 from maggots in dead animals, etc., was due to the con- 

 fusion of this fly with the honey-bee. 



In another group of the family, the adult flies of which 

 also quite closely resemble bees, the larv^ are parasitic in 

 the nests of honey- and bumble-bees, feeding upon their 

 larvae. 



But the larvae of possibly the most typical portion of the 

 family, embracing the genus Syrplms and its near allies, 

 are entirely predaceous upon plant-lice. Rarely can a 

 colony of plant-lice be found without some of these little 

 enemies hard after them. 



