52 NEW ZEALAND ENTOMOLOGY. 



benefiting mankind by the removal of considerable quan- 

 tities of effete matter, which if allowed to remain could 

 not fail to be injurious. 



Family TlPULlD^E. 

 Bibio nigrostigma (Plate V., fig. 5, 5a larva, 5b pupa). 

 This insect is very abundant during the spring months, 

 but rapidly disappears, and few specimens are noticed after 

 Christmas. Its larva (Fig. 5a) inhabits the woody powder 

 often found under logs, which frequently consists of the 

 accumulated excrement of wood-boring insects. It is gre- 

 garious in its habits, being found in large companies of fifty 

 or a hundred individuals. When first disturbed these ap- 

 pear as a wriggling mass, but very shortly become so still 

 that they can only be distinguished with the greatest diffi- 

 culty from morsels of bark. A considerable portion of the 

 powdered wood is also retained on the body of the insect 

 by a row of short spines situated in the middle of each 

 segment, which helps to render the larva still more incon- 

 spicuous. In this condition it remains for at least eight 

 months, during which time growth takes place very slowly. 

 About September the larvae separate, each being afterwards 

 transformed into a small yellowish pupa (5b), whose ab- 

 dominal extremity is usually retained within the old skin, 

 thus closely resembling that of the genus Ceratopogon. I 

 have figured this pupa entirely naked, in order to show 

 its characteristics, some of which are rather remarkable, 

 more completely, the agglutination of nearly all the 

 anterior portions of the body being especially noteworthy. 

 The perfect insects may be found everywhere, the males 

 sucking honey from the flowers and performing many 

 antics in the air, often clinging hold of one another and 

 whirling about together. The female seldom flies, but is 

 usually observed crawling about fences or the trunks of 

 trees. She may be at once recognized by her heavy body 



