l3 NEW YORK STATE JIUSEUxM 



it is easy to see how these legless, degraded forms could have been derived 

 from the more common type through a reduction of their various organs. 



1 he larval stage is frequently of prime importance to the economic 

 entomologist because it is while in this form that many insects commit their 

 greatest depredations. The young of our sawflies may be recognized by 

 their usually cylindric form and by their having i8 to 22 legs including the 

 6 true or thoracic legs, while caterpillars or larvae of butterflies and moths 

 are usually provided with from 8 to 16. The young of the more highly 

 developed bees and flies, as previously stated, are footless, maggot-like 

 creatures and the young of most beetles possess the 6 thoracic legs and are 

 often provided with a fleshy appendage at the posterior extremity, though 

 in some, such as snout beetles and man)- wood borers, all the usual 

 locomotive appendages are wanting. 



The larval stage of insects, like the others, may be met with under 

 very diverse conditions and in all seasons of the year, though its dura- 

 tion m each species is usually somewhat closely limited. The caterpillar 

 [pi. 7, fig. i] sheds its skin when full grown and changes to a pupa, a 

 stage which is frequently subconical and often of a brownish incon- 

 spicuous color. 



Pupa. The assumption of this stage is usually preceded by the larva 

 betaking itself to some sheltered place where a protective cocoon or cell 

 may be prepared. The cocoon may be very delicate and netlike as in the 

 clover leaf weevil, P h y t o n o m us p u n c t a t u s Fabr. or with an outer net 

 and inner close woven cocoon as in Climacia or a more or less homo- 

 geneous silken covering as in the common silkworm. Some native species 

 incorporate leaves or portions of them in their cocoons like the [jromethea 

 moth. The larvae of many moths construct very perfect earthern cells in 

 which to undergo their final transformations while others depend on the 

 partial shelter of a crevice or curled leaf. Many butterflies undergo trans- 

 formations in exposed situations and their chrysalids present some interest- 

 ing adaptations to surrounding objects. The angular protectively colored 

 chrysalis of the spiny elm caterpillar [pi. 10, fig. 10] is an exceedingly 



