252 



INSECTS. PHYLUM ARTHROPODA 



oo the spindle tree. Euonymus europaea ; after a few wingless 

 generatioiis have been prodnced in the early summer, winged, 

 bat still parthenogenetic. females a^jear, and migrate to beans 

 (VicU) and other plants, where more parthenogoietic broods, 

 some winged and some win^ess, are produced. When the winged 

 sexnal individoals are formed, both s-x-s migrate back to the 



Ori£r 13- Ephemeroptera. The most strikinz f-ature of 

 the ma\-flies, and that which gives its name to the order, is 





Fic. 184. — ^Marfly lar%-a. 

 Frcan TboDQaoD, aiter 



E^tOCL. 



FiG- 185. 



Tbe body loose in dorsal 

 c. yj. — Afttrr NuttaJL 



the brief life-span of the imago, sometimes a mere day, and 

 never more than a few. The imagfrn^ do not feed, and have 

 vestigial mouth-parts, but those of the larv a: are biting. The larvae 

 are aquatic naiads, which, except in the first instar, possess tracheal 

 giDs, Kk*? small i»ings, attadied to the abdominal segments 

 (Fig. I _. Both imago and larva have long cerci and a long 

 caudal filament, giving a characteristic triple tail which makes 

 tbem ea5>' to recognise. 



Ori^ 14. Malloph.^ga- The bird hce are wingless and have 



bitmg mouth-p>art5 uith whidi they feed on particles of feather 



are parasitic on mammals, not birds; hair. The chief 



