THE SMALLEST INSECTS. 



insect egg or a single scale-insect indicates the small size 

 of many species. Others feed on larger prey as, for in- 

 stance, Pteromalus puparum on the cabbage- worm. Only 

 last week a small boy brought in numbers of the yellow 

 Spilochalcis mari<z (Plate LXXXVIII) which had come out 

 of cecropia cocoons he had gathered. 



SERPHOIDEA 



This superfamily is made up of the PROCTOTRYPID^E 

 and PELECINID/E of the older system of classification and 

 is now divided into a number of different families. Almost, 

 or quite, all are parasitic. Although they are nearly all 

 small, some being, in fact, the smallest of our insects and 

 practically invisible to the naked eye, Pelecinus polyturator 

 (Plate LXXXVIII) is quite large. It is the only species 

 of Pelecinidae within the geographic limits of this book, 

 and is parasitic upon the larvae of A lay beetles, Phyllophaga. 

 The elongate abdomen of the female enables her to reach 

 the underground larvae ; the more normally shaped male is 

 quite rare. The small Proctotrupida? breed in the eggs 

 of various insects, some even swimming with their wings 

 under water to reach the eggs of aquatic forms. 



FORMICOIDEA 



There is only one family, FORMICID.E, of Ants. In 

 addition to males and sexual females, nearly every species 

 has modified females, which rarely reproduce. These 

 are the workers. There may be more than one sort of 

 worker, in which case they are usually much alike except 

 in size but some may be differentiated as "soldiers." It 

 is the workers which we ordinarily see and, as they never 

 have wings, many people think that all ants are wingless. 

 However, the sexual forms, which are usually produced 

 but once a year, are fully winged and indulge in a nuptial 

 flight. After it, the males die but the females lose their 

 wings and settle down to the stay-at-home task of produc- 

 ing offspring. The rearing of all except the first of these 

 offspring is attended to by the old-maid daughters unless 



415 



