310 TAXIDEIIMY AND ZOOLOGICAL COLLECTING. 



food-plant, it is often possible to obtain their eggs in consider- 

 able numbers. The insects thus confined should be supplied 

 with food and drink. This may be done by sprinkling- upon 

 the leaves water sweetened with sugar, or preferably honey. 

 The females of many of the bombycid moths and hawk-moths 

 will lay freely, if enclosed in a dark box, without the presence of 

 the food-plant. When eggs are found and their parentage is 

 unknown, a few should be preserved as hereafter described, and 

 the remainder should be retained and kept until they have 

 been hatched and the perfect insect lias been reared therefrom. 

 Insect eggs may often be obtained by dissecting- the gravid fe- 

 male, but it is always preferable to obtain them, if possible, 

 after oviposition has taken place, since in many cases the color 

 of the egg- in the oviduct is somewhat different from what it is 

 after having- bseii laid. 



The eg-gs of insects may be deprived of their vitality by im- 

 mersion in alcohol or by exposure to heat. The albumen of 

 ova coagulates at 160 F., and the temperature of the egg- 

 should not be raised above 175. They are best killed by being- 

 placed in the stove used for drying- the skins of larvae, which is 

 described on page 315. It is better to kill by means of a gentle 

 heat than by immersion in alcohol, as by the latter process a 

 change in color is sometimes produced. After they have been 

 deprived of their vitality they may be preserved in small 

 phials in dilute giycerine, or, if this cannot be had, in a solu- 

 tion of common salt. The phials should be kept tightly 

 corked, and should be numbered by a label, w r ritten in lead pen- 

 cil and placed within the bottle, to correspond, with the note 

 made in the collector's note-book giving an account of the place 

 of discovery, the food-plant, the date when found, and the name 

 of the insect which deposited them, if known. In the latter 

 case it is best to put the name of the insect in the phial with 

 the number. Unless insect eggs are preserved in a fluid they 

 are apt in many cases to shrivel with the lapse of time and be- 

 come distorted, through the drying up of their contents, which, 

 on account of their small size, it is impossible to void. The 

 shell of some eggs is often very neatly voided by the escape of 

 the larva, but there is generally a large orifice left, the color is 

 frequently materially altered, and great vigilance in securing 



