SAWFLIES 5 I 5 



with remarkable forked spines. These spines may exist during 

 part of the larval life, and completely disappear at one of the 

 moults. The creatures are as a rule very sluggish, and move 

 about much less than Lepidopterous larvae ; many of them, when 

 alarmed, have the power of exuding a disagreeable liquid, either 

 from the mouth or from pores in the skin ; in the latter case it 

 may be sent as a sort of spray to some little distance from the 

 body. This operation is said to be very efficacious as a means 

 of protecting the larvae from the attacks of parasitic flies that 

 are desirous of laying eggs in their bodies. One peculiarity as 

 to their colour has attracted the attention of Keaumur and sub- 

 sequent naturalists, namely, that in the case of many species a 

 great change takes place in the colour during the life of the 

 larva, and more especially at the period of the last moult. The 

 change to the pupal state usually takes place in a cocoon, and 

 some species have the peculiar habit of forming a double cocoon, 

 the outer one being hard and coarse, while the inner is beauti- 

 fully delicate. The cocoon is sometimes formed in the earth, 

 and in that case it may be to a large extent composed of earthy 

 matter. The Insect frequently remains a long time in its cocoon 

 before emerging as a perfect Insect ; however long this time may 

 be, it is nearly all of it passed in the larval state ; when the 

 Insect does change to a pupa it speedily thereafter emerges as a 

 perfect Insect. In the pupa the parts of the imago may be seen 

 enveloped in a very delicate, transparent skin. 



In Brazil Dielocerus ellisii, a sawfly allied to Hylotoma, 

 constructs a nest in which the cocoons of many specimens 

 are crowded together, being packed side by side like the cells 

 in the comb of the bee, while the whole mass is protected by 

 a thick outer wall. It is not known in what manner this 

 communal work is carried out, but it is interesting to note that 

 the cocoons assume to a considerable extent the hexagonal form 

 of the cells in the comb of the bee. Some doubt was expressed 

 as to the interpretation put on this structure by Curtis, but his 

 observations have been confirmed by Smith and Peckholt. 



Several species of sawflies are known to be very injurious to 

 crops. One of these the sawfly of the turnip, AtJialia spinarum 

 (centifoliae Panz.) sometimes commits excessive depredations 

 on the turnip crops in this country as well as on the continent of 

 Europe ; its life-history and anatomy were described by Newport 



