398 STATE HORTICULTURAL SOCIETY. 



fourth o£ an inch long. The caterpillar remains inactive after the parasite 

 escapes and in a few days dies because of the internal injury done by the 

 parasite. Safe in its tightly woven cocoon, the parasite remains till the 

 following spring when it comes forth as a winged fly to attack other 

 caterpillars. 



This season none of the Microplitis have been seen, but another parasite 

 has been even more destructive to the Mamestra. These parasites are so 

 minute they can hardly be seen with the naked eye, being three fourths 

 of a millimeter, or one thirty-fifth of an inch long. They do not attack 

 the caterpillar but mature inside the eggs of the Mamestra and destroy them 

 before they hatch. From two thirds to three fourths of most of the 

 bunches were destroyed in this way. The parasitized eggs change to a dull 

 lead color in a few days. Mr. Ashmead writes me that he has bred the 

 same species from the cotton boll worm (Heliothus armigera) of the 

 south and has given them the name Telenomus heliothidis. 



In addition to these two parasites on Mamestra picta, two predaceous 

 species were seen doing their share in destroying the eggs. One of these 

 is a lady bird beetle {Megilla maculaia), and the other is the tarnished 

 plant bug {Lygus tercicus) previously treated of as a celery pest. Our 

 celery pest in this case becomes a destroyer of another pest by inserting 

 the lance of its beak into the eggs and sucking the contents. The lady 

 bird beetle eats shell and all, but the bug leaves the shell entire though 

 usually it is split where the lance enters. Seeing every once in a while 

 quite a number of the egg cases empty and split open in this peculiar man- 

 ner, I was led to watch for the cause of it. I soon found a tarnished plant 

 bug at work on a cluster of eggs and watched it for some time. The eggs 

 seemed to be greatly relished by the bug as it would repeatedly return 

 when driven away and begin feeding at once. With so many vigilant foes 

 to overcome, the zebra caterpillar will have difficulty in reaching maturity.. 



FOOD PLANTS. 



The caterpillars of this species are very general feeders and are 

 especially fond of most garden crops. They sometimes become plentiful 

 enough to be injurious. Dr. Harris, in his " Insects Injurious to Vege- 

 tation," p. 451-2, gives us one of the earliest accounts of its destruct- 

 ive work. He mentions it as injurious to cabbages, cauliflowers, spinach, 

 and beets. 



Dr. Riley in his 2d Mo. Report, p. 112 (111.), after giving habits and 

 history, mentions, besides many weeds and flowers, asparagus in addition 

 to those given by Harris. 



In the 6th 111. Report, p. 60, Thomas reports it being very partial to the 

 leaves of the pea. 



In the 5th Ent. Report of N. Y., p. 206-10 (111.), Dr. Lintner gives a 

 very complete article on the species and adds currants and buckwheat to 

 the list of food plants. 



Here at our college we found them common on two species of clover,, 

 alsike and alfalfa. 



EEMEDIES. 



When a cluster of eggs is found on a celery leaf or the very young larvae 

 are seen, they can be very easily crushed. With the older ones Dr. Lintner 

 has found that pyrethrum powder mixed with five parts of flour and dusted . 



