ENTOMOLOGICAL WORKS. 97 



which arise from them, should be noted, besides the general 

 form of the body. The lines along the body are called dorsal, 

 if in the middle of the back, subdorsal; if upon one side, lat- 

 eral, and ventral when on the sides and under surface, or stig- 

 matal if including the stigmata or breathing pores, which are 

 generally parti-colored. Indeed, the whole biography of an 

 insect should be ascertained by the observer ; the points to 

 be noted are : 



1. Date, when and how the eggs are laid ; and number, size, 

 and marking of the eggs. 



2. Date of hatching, the appearance, food-plant of larva, 

 and number of days between each moulting ; the changes the 

 larva undergoes, which are often remarkable, especially before 

 the last moulting, with drawings illustrative of these ; the hab- 

 its of the larva, whether solitary or gregarious, whether a day 

 or night feeder ; the Ichneumon parasites, and their mode of 

 attack. Specimens of larvae in the different moultings should 

 be preserved in alcohol. The appearance of the larvae when 

 full-fed, the date, number of days before pupating, the forma- 

 tion and description of the cocoon, the duration of larvae in the 

 cocoon before pupation, their appearance just before changing, 

 their appearance while changing, and alcoholic specimens of 

 larvae in the act, should all be studied and noted. 



3. Date of pupation ; description of the pupa or chrysalis ; 

 duration of the pupa state, habits, etc. ; together with alcoholic 

 specimens, or pinned dry ones. Lepidopterous pupae should be 

 looked for late in the summer or in the fall and spring, about 

 the roots of trees, and kept moist in mould until the imago 

 appears. Many Coleopterous pupae may also occur in mould, 

 and if aquatic, under submerged sticks and stones, and those 

 of borers under the bark of decaying trees. 



4. Date when the insect escapes from the pupa, and method 

 of escape ; duration of life of the imago ; and the number of 

 broods in a season. 



ENTOMOLOGICAL WORKS. The titles of a few of the most im- 

 portant works on Insects are given below. The more advanced 

 student should, however, possess Dr. Hagen's Bibliotheca En- 

 tomologica, 8vo, 2 vols., Leipzig, 1862-3, which contains a 



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