332 DAVENPOKT ACADEMY OF NATURAL SCIENCES. 



DISEASES. 



Besides disease caused by insufficient food, this insect appears to be 

 subject to some one or u^ore diseases whose nature is unknown to me. 

 At all events a considerable number of both sexes and of all ages are 

 noticed to die without any assii^nable cause, wliile their companions on 

 the same leaf remain healthy. Some of tlie deaths are no doubt caused 

 by wounds from enemies, others by difficulty in moulting, etc. The 

 most critical periods, or those in wliich the most deaths are noticed ap- 

 pear to be as follows : the young lice just after settling on the leaf, the 

 male pupse just before completing their transformation, and the females 

 in the spring, probably not having sufficient vitality to revive from the 

 winter dormancy. Diseases of the ovaries have also been observed. In 

 some the ovicapsules will be developed as usual, but with the ovum 

 abortive or absent; in others the spermatheca becomes contracted and 

 shriveled. In tliese cases a small amount of waxy matter is secreted, 

 but no eggs are laid. An abnormally formed egg has already been men- 

 tioned. The females which have settled on the underside of the leaves 

 against the veins are nearly always distorted, often nearly straight on 

 one side and convex on the other, making them very lop-sided. 



The depletion of the trees naturally reacts on the insects, and it is a 

 fact of frequent notice that the females on healthy trees are larger, of 

 more healtiiy appearance, and lay more eggs than ihose on sickly trees. 

 It appears that sickly trees produce a greater number of males, and that 

 on them both males and females mature earlier, by several days or even 

 a week, than on healthy trees. In explanation of tliis fact. Dr. George 

 Engelmann. the Botanist, has suggested to me that the sap of diseased 

 trees contains more sugar than that of healthy trees. 



PARASITES. 



I have observed the following parasites in Pulvinaria innumerabilis : 



1. The minute spherical bodies with a vibratory movement already 

 described on page 326, which may possibly be Bacteria. 



2. The oval bodies ( Pseudo-navicellce f ) described on page 326. 



3. Elongated oval or fusiform bodies divided into two or four large 

 quadrilateral cells. So far only noticed a few times in females at the 

 time of the appearance of the males. 



4. Coccophdcni)' lecanii Smith,* a small hymenopterons insect belong- 

 ing to the family Chalcidce. It is of a dark ashy black color with a large 

 transverse lunate spot of bright yellow on the thorax behind the wings, 

 and the feet paler. The wings are quite hairy, the fore wings have a 

 single subcostal vein exteiiding parallel with the costa more than half 

 way to the tip where it sends a very short branch inward and outward 

 abruptly terminating in an enlargement. The pupa is of a pale gray 



* I am Tcrj- mnch inclined to think that PlatygoBter lecanii described hy Fitch in his 5th 

 New YorVw Report, as infe.«liug Lecaninm qiiercilronn may prove to be really a Coccophngus 

 nearly allied if not identical with this species. The description applies too well to easily be- , 

 lieve that the two species belong to diflferent families. In this event Dr, Fitch's reference to 

 the Proctotrupidee is of course wrong. 



