148 NATURAL SCIENCE [September 



(should they care to do so), if the Government or the County 

 Councils would take up the question officially and systematically. 

 But such a work would involve much original research. 



Amekican Economic Entomology 



We have also received from the U.S. Department of Agriculture 

 a short but interesting pamphlet by Mr C. L. Marlott on " Insect 

 Control in California." The well-known plan of introducing lady- 

 bird beetles to prey upon the imported scale-insects which 

 devastate the western fruit-orchards has been successfully extended ; 

 while an efficient artificial insecticide has been found in hydrocyanic 

 acid gas with which the trees are fumigated after being covered with 

 a temporary canvas tent. Mr F. H. Chittenden writes on the 

 European Asparagus beetles which, like so many old-world insects, 

 have been introduced into the Atlantic States. Dr L. D. Howard 

 gives an illustrated account of various portable steam pumping- 

 engines used for spraying trees with insecticide fluids. 



Glands in Insects 



In the latest part of the Transactions of the Entomological 

 Society of London (1897, pp. 113-126, pt, v.), Mr Oswald H. Latter 

 describes the structure and function of the sternal gland found in 

 the prothorax of the caterpillar of the " Puss " moth (Cerura vinula). 

 The formic acid secreted by this gland has long been recognised 

 as a defence to the larva against its enemies. Mr Latter has now 

 shown that at the end of larval life the secretion has another 

 function. Mixed with the silk the acid serves to make the cocoon 

 which contains the pupa exceedingly hard and waterproof as well as 

 strongly adherent to foreign substances such as the chips of wood 

 which this caterpillar habitually works into its cocoon. 



Mr Latter points out that in other lepidoptera and insects 

 of different orders, many segments of the body possess glands which 

 may reasonably be considered serially homologous with that under 

 consideration ; he suggests that all these glands represent the coxal 

 glands of arachnids. The prothoracic gland of C. vinula opens into 

 a shallow vestibule, whence arise branched eversible tubes bearing- 

 groups of spines in their cavities. Mr Latter is unable to suggest a 

 satisfactory function for these tubes, but he points out that the 

 groups of spines recall the parapodial setae of chaetopods, and that 

 the whole structure supports Mr Bernard's view that such glands 

 are derived from the acicular gland sacs of ringed worms. Should 

 these relationships prove to be correct, Mr Latter believes that they 

 " will go far towards establishing the primitive nature of the cruci- 

 form larva of which many observers are already in favour." 



