192 INSTRUCTIONS FOR COLLECTING INSECTS. 



themselves in every direction, and spots which were previously very 

 small in consequence of the overlapping of the scales, when the pro- 

 cess is completed, have twice or thrice the original dimensions. The 

 process of wing expansion should not be permitted to take place in 

 the moist atmosphere of the vivarium, except in the '' micros," nor 

 should the insect be disturbed or killed until after it begins to use its 

 wings voluntarily ; otherwise it will be difficult to make good prepa- 

 rations of the wings. These bred insects on first being handled or 

 when they first feel the efi'ect of chloroform, void a quantity of excre- 

 mentitious matter, which the student must be careful does not soil the 

 wings. 



The practice of the old trans- Atlantic collectors of obtaining pupae by 

 digging for them at the roots of trees has been recently revived in Eng- 

 land with the most successful results by the Rev. Joseph Greene. He 

 says that " meadows and parks, with scattered timber trees, are gene- 

 rally the best localities ; next to meadows and parks come woods ; but 

 searching in woods is a tedious and fatiguing affair, and requires some 

 experience ; it is in vain to examine the dense portions, it is equally 

 vain to dig at the roots of trees in such localities, and you will rarely 

 find anything unless upon trees of considerable growth ; the thick 

 moss which collects about the trunks and roots is the part to be 

 examined. Bombyces are generally found under the moss which 

 covers spreading roots and not on the trunks, which seem to be pre- 

 ferred by the Geometrae. The best localities in woods are the borders 

 or open places; such places when elevated or facing the north are 

 generally the most productive. The only instrument I use is a com- 

 mon garden trowel ; the form is immaterial, perhaps a rounded blade 

 is best, as passing with greater ease between the roots. The trees 

 which I have found the most productive are the following : elm, 

 oak, ash, poplar, beech, willow, and alder. [I would likewise add, 

 for the American collector, the walnut;^ the wild cherry^ the apple 

 tree, the linden, and the hickory.] In digging, it must be borne in 

 mind that all pupae are close to the trunk ot the tree, seldom more 

 than two inches distant ; frequently the trunk of the tree forms one 

 side of the cocoon, especially the cocoon of such insects as spin ; the 

 chrysalis also lies almost invariably close to the surface of the earth. 

 Insert the trowel about three inches from the trunk, to the depth of 

 two inches or so ; then push it to the tree and turn up ; if the soil be 

 dry and friable, without grass, knock it gently with the trowel, which 

 will be suflicient. If, however, there be grass, you must proceed more 

 cautiously ; take up the sod on the left hand, knock it very gently 

 with the trowel, and those pupte which merely enter the ground will 

 drop out ; to find those which spin, you must carefully examine the 

 sod, tearing the roots of the grass asunder ; these are, of course, much 

 the most difficult to find, the cocoons being generally of the color of the 

 earth. It is useless to try sticky or clayey grounds, the caterpillars being 

 unable to penetrate it ; in searching under moss the best plan is to 

 loosen the edge, then to tear it gently ofi", observing whether any 

 pupae fall. Look at the trunk of the tree to see if anything adheres 

 to it, and then carefully examine the moss itself; experience alone 

 will enable you to detect a spun cocoon. 



