r* 
O 
less than three generations yearly in central Colorado. The num¬ 
ber of worms increases many fold with each generation, so it is im¬ 
portant 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. 
Food Plants. —Although this insect does its chief injury to 
cabbage and cauliflower, it also attacks many other cruciferous 
plants, as kale, radish, turnip, and mustard. 
\ • 
Natural Enemies. —At Fort Collins there are three very im¬ 
portant parasites that attack this insect. The most important of 
these is a minute green fly (* Pteromalus puparum Linn.), belonging 
to the order Hymenoptera. This little parasite does not kill the 
larva, or worm, but the chrysalis. The chrysalids lose their green 
color and become very dark, and, in a short time, instead of butter¬ 
flies, there will appear from each chrysalis forty or fifty specimens 
of this parasitic fly. 
On the 9th of September, 1891, a quantity of chrysalids were 
gathered from the College garden, and in every case they were para¬ 
sitized by this insect. 
Another small, four-winged parasite (*Apanteles glomeraius- 
Linn.), which is black in color, attacks the larvae and destroys many 
of them. By tearing open nearly mature worms, the maggots of 
this parasite can often be found in large numbers inside. Before 
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 disguise. These little parasites are of great service to the gard¬ 
ener, and should not be destroyed. 
Another parasite that is common here, attacking the cabbage' 
worms, is a twonvinged fly (** Anthoniyia sp.), which closely resem¬ 
bles the common house-fly. The flies themselves will seldom be 
noticed, but among the leaves of the cabbages late in summer will 
be found numerous barrel-shaped, mahogany-colored objects about 
one-eighth of an inch in length. These are the pupae—or puparia,, 
as the entomologist would say—of this fly. These puparia should 
not be destroyed, as each incloses an insect very beneficial to the' 
gardener. 
The time may come when these allies of the gardener will bo 
numerous enough to exterminate the enemy without his assistance*. 
* Determined by W. H. Ashmead, Dep. of Agr., Washington, D. C. 
** Determined by Prof. C. H. T. Townsend, formerly of Las Cruces, N. M. 
