To observe insects in English, you can say "to watch insects" or "to observe insects." The word "observe" comes from the Latin word "observare," which means "to watch" or "to pay attention to." Here are some examples of sentences using this phrase in English:

I like to observe insects in my garden.

The scientist observed the insects under the microscope.

We observed many different types of insects on our nature hike.

In Chinese, you can say "观察昆虫" (guānchá kūnchóng) to mean "to observe insects." Some examples of sentences using this phrase in Chinese are:

我喜欢在花园里观察昆虫。 (Wǒ xǐhuan zài huāyuán li guānchá kūnchóng.)

科学家在显微镜下观察昆虫。 (Kēxuéjiā zài xiǎnwèijìng xià guānchá kūnchóng.)

我们在野外徒步旅行中观察到许多不同类型的昆虫。 (Wǒmen zài yěwài túbù lǚxíng zhōng guānchá dào xǔduō bùtóng lèixíng de kūnchóng.)