62 
be exempt from the seed-caterpillar, and we have actually found it on 
so-called mammoth, which appeared to be a cross between mammoth 
and the common red clover. 
Hatching usually near the base of a green clover-head, the larva 
eats into the head, destroying the green llorets as it goes. A small 
green head is often destroyed entirely, before it is many days old ; a 
larger head is injured only locally at first, remaining green on one 
side, while the other and unaffected side may come into full bloom 
(PI. II., Fig. 9). To judge from the external appearance of the head, 
either the seed-caterpillar or the seed-midge larva might be the author 
of the mischief, and both are often present at the same time. A midge 
larva, however, is hidden away in the ovary of a single floret, while the 
seed-caterpillar makes a large dirty excavation involving many florets, 
and is readily brought to light by tearing open the clover head. The 
caterpillar attacks particularly the bases of the florets, and eats every- 
thing, including the semifluid ovules ; occasionally it eats a soft green 
seed but it does not eat into seeds that have hardened. Not infre- 
quently two larvae are found in the same head. Even when the direct 
injury is confined to a portion of a clover head, the entire head is 
ruined, for it at length dries up and loses the rest of its florets, leaving 
only the dead brown receptacle. 
Less conspicuous, tho not inconsiderable, is the injury at the 
crown of the plant, done chiefly in September and October, by cater- 
pillars of the same species feeding on the young leaves. 
The total amount of injury by this insect is, of course, variable. 
In New York, Comstock once found 15 to 20 percent of the heads of 
red clover infested. In Michigan, Webster saw clover injured to the 
extent of 95 percent. In Iowa, Gillette, Osborn, and Gossard have 
found the severest kind of infestation. While not sufficiently abun- 
dant to attract attention, the insect is, nevertheless, the unsuspected 
cause of a considerable reduction in the seed crop ; for the destruction 
of one head by a caterpillar means a loss of more than one hundred 
seeds. 
Stages. — The egg, hitherto undescribed, is at first green, then yel- 
lowish white, and is almost orbicular as seen from above, tho it is 
flattened ventrally; the surface is finely granulate and iridescent. The 
dimensions are as follows: length, 0.275 mm.; width, 0.26 mm.; and 
height, 0.21 mm. 
The full-grown caterpillar, 7 or 8 mm. long, has the usual five 
pairs of prolegs. The color varies in accordance with the nature of 
the food (green tissue, or red floral tissue) from dirty white, tinged 
with green, to orange, as in b'igure 10 of Plate 11. 1'he alimeiilar\' canal 
with its greenish or purplish contents shows thru the translucent skin 
and shifts in position as the caterpillar moves. The head is dark 
brown and polished, caudate occipitally, and deeply immersed in the 
prothorax. Prothoracic shield yellowish with a brown posterior bor- 
der interrupted by a median line of white ; or else dark brown with a 
clear median line. The body bears not a few pale stiff hairs, and the 
