16 



THE COLLECTORS' MONTHLY. 



the hand, often entirely ruining it. 

 In from two to three weeks after 

 hatching the worms become mature, 

 and then change to a green chrysalis, 

 in which stage they eat nothing, and 

 remain quiet unless disturbed. If the 

 worms were very numerous, some of 

 these chrysalids may be found attached 

 to the leaves of the cabbage, but most 

 of the worms will crawl away to un- 

 dergo their transformations upon other 

 near objects. 



In the course of a week or ten days, 

 the chrysalis splits along the back and 

 the butterfly emerges. In a few days 

 more the females begin to deposit eggs 

 for a second brood of worms. 



How many rounds of developement 

 there are in a year depends upon the 

 length of the summer season. There 

 are probably not less than three gene- 

 rations yearly in central Colorado. 



The number of worms increases 

 many fold with each generation, so it 

 is important that the first brood be as 

 largely destroyed as possible. If 

 three-fourths of the first brood were 

 destroyed, there would be only one- 

 fourth as many in the second brood as 

 if none of the first brood were killed. 



NATURAL ENEMIES. 



At Fort Collins there are three very 

 important parasites that attack this 

 insect. The most important of these 

 is a minute green fly (Pteromalus pu- 

 parum Linn.), belonging to the order 

 Hymenoptera. This little parasite 

 does not kill the larvae, or worm, but 

 the chrysalis. The chrysalids lose 

 their green color and become very 



dark, and, in a short time, instead 

 of butterflies, there will appear from 

 each chrysalis forty or fifty specimens 

 of this parasitic fly. 



Another small, four-winged parasite 

 (Apmiteles glomeratus Linn.), which 

 is black in color, attacks the larvae and 

 destroys many of them. By tearing 

 open nearly mature worms, the mag- 

 gots of this parasite can often be 

 found in large numbers inside. Be- 

 fore the worm changes to a chrysalis, 

 these maggots eat through the body 

 wall, and each spins about itself a 

 yellowish silken cocoon. Each of 

 these little cocoons is about one-eighth 

 of an inch long, and all together form 

 a mass a half-inch or more in length. 

 These masses are usually found upon 

 the leaves of infested plants, and 

 would be liable to be taken by the 

 gardener as some insect enemy in dis- 

 guise. These little parasites are of 

 great service to the gardener and 

 should not be destroyed. 



C. P. Gillette. 



Send in your subscriptions now ! 



WANTS, EXCHANGES, AND FOR SALES. 



Brief special announcements. "Wants." "Exchan- 

 ges," "For Sales," inserted in this department for 50c 

 per 10 words. Notices of over 40 words, charged at the 

 rate of one cent per each additional word. No notice 

 inserted for less than 50c. Cash or specimens must 

 accompany order. 



First class specimens with data will be accepted in 

 payment at one-half list value. 



TO EXCHANGE.— A "New Rogers " Scroll saw in 

 excellent order for best offer of first class specimens 

 with data. Make offers immediately. J. B. PECK, 

 Newburgh, N. Y. 



TRICKS AND MAGICAL APPARATUS, all kinds 

 for sale. Send 10 Cents, silves or stamps, and get cir- 

 culars and price list and get a nice trick free. Engage- 

 ments taken for Entertainments in Magic and Punch 

 and Judy. Address all orders to Prof. Wm. G. Thorpe, 

 60 Smith Street, Newburgh, N. Y. 



